Class: java.lang.StringBuffer

A thread-safe, mutable sequence of characters. A string buffer is like a String, but can be modified. At any point in time it contains some particular sequence of characters, but the length and content of the sequence can be changed through certain method calls.

String buffers are safe for use by multiple threads. The methods are synchronized where necessary so that all the operations on any particular instance behave as if they occur in some serial order that is consistent with the order of the method calls made by each of the individual threads involved.

The principal operations on a StringBuffer are the append and insert methods, which are overloaded so as to accept data of any type. Each effectively converts a given datum to a string and then appends or inserts the characters of that string to the string buffer. The append method always adds these characters at the end of the buffer; the insert method adds the characters at a specified point.

For example, if z refers to a string buffer object whose current contents are "start", then the method call z.append("le") would cause the string buffer to contain "startle", whereas z.insert(4, "le") would alter the string buffer to contain "starlet".

In general, if sb refers to an instance of a StringBuffer, then sb.append(x) has the same effect as sb.insert(sb.length(), x).

Whenever an operation occurs involving a source sequence (such as appending or inserting from a source sequence) this class synchronizes only on the string buffer performing the operation, not on the source.

Every string buffer has a capacity. As long as the length of the character sequence contained in the string buffer does not exceed the capacity, it is not necessary to allocate a new internal buffer array. If the internal buffer overflows, it is automatically made larger. As of release JDK 5, this class has been supplemented with an equivalent class designed for use by a single thread, StringBuilder. The StringBuilder class should generally be used in preference to this one, as it supports all of the same operations but it is faster, as it performs no synchronization.

Authors:
@author Arthur van Hoff
See:
@see StringBuilder
@see String
Since:
@since JDK1.0

Inheritance

Superclass tree: Implements:

Methods

  • StringBuffertop

    public StringBuffer()
    Constructs a string buffer with no characters in it and an initial capacity of 16 characters.
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  • StringBuffertop

    public StringBuffer(int capacity)
    Constructs a string buffer with no characters in it and the specified initial capacity.
    Parameters:
    @param capacity the initial capacity.
    Exceptions:
    @exception NegativeArraySizeException if the capacity argument is less than 0.
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  • StringBuffertop

    public StringBuffer(CharSequence seq)
    Constructs a string buffer that contains the same characters as the specified CharSequence. The initial capacity of the string buffer is 16 plus the length of the CharSequence argument.

    If the length of the specified CharSequence is less than or equal to zero, then an empty buffer of capacity 16 is returned.

    Parameters:
    @param seq the sequence to copy.
    Exceptions:
    @exception NullPointerException if seq is null
    Since:
    @since 1.5
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  • StringBuffertop

    public StringBuffer(String str)
    Constructs a string buffer initialized to the contents of the specified string. The initial capacity of the string buffer is 16 plus the length of the string argument.
    Parameters:
    @param str the initial contents of the buffer.
    Exceptions:
    @exception NullPointerException if str is null
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  • appendtop

    public synchronized StringBuffer append(char c)
    Appends the specified character to this Appendable.
    Parameters:
    @param c The character to append
    Return:
    @return A reference to this Appendable
    Specified by:
    append from Appendable
    Override hierarchy:
    append from AbstractStringBuilder
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  • appendtop

    public synchronized StringBuffer append(double d)
    Appends the string representation of the double argument to this sequence.

    The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this sequence.

    Parameters:
    @param d a double.
    Return:
    @return a reference to this object.
    See:
    @see String.valueOf(double)
    @see StringBuffer.append(java.lang.String)
    Override hierarchy:
    append from AbstractStringBuilder
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  • appendtop

    public synchronized StringBuffer append(float f)
    Appends the string representation of the float argument to this sequence.

    The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this string sequence.

    Parameters:
    @param f a float.
    Return:
    @return a reference to this object.
    See:
    @see String.valueOf(float)
    @see StringBuffer.append(java.lang.String)
    Override hierarchy:
    append from AbstractStringBuilder
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  • appendtop

    public synchronized StringBuffer append(int i)
    Appends the string representation of the int argument to this sequence.

    The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this sequence.

    Parameters:
    @param i an int.
    Return:
    @return a reference to this object.
    See:
    @see String.valueOf(int)
    @see StringBuffer.append(java.lang.String)
    Override hierarchy:
    append from AbstractStringBuilder
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  • appendtop

    public synchronized StringBuffer append(long lng)
    Appends the string representation of the long argument to this sequence.

    The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this sequence.

    Return:
    @return a reference to this object.
    See:
    @see String.valueOf(long)
    @see StringBuffer.append(java.lang.String)
    Override hierarchy:
    append from AbstractStringBuilder
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  • appendtop

    public StringBuffer append(CharSequence s)
    Appends the specified CharSequence to this sequence.

    The characters of the CharSequence argument are appended, in order, increasing the length of this sequence by the length of the argument.

    The result of this method is exactly the same as if it were an invocation of this.append(s, 0, s.length());

    This method synchronizes on this (the destination) object but does not synchronize on the source (s).

    If s is null, then the four characters "null" are appended.

    Parameters:
    @param s the CharSequence to append.
    Return:
    @return a reference to this object.
    Since:
    @since 1.5
    Specified by:
    append from Appendable
    Override hierarchy:
    append from AbstractStringBuilder
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  • appendtop

    public synchronized StringBuffer append(CharSequence s, int start, int end)
    Appends a subsequence of the specified character sequence to this Appendable.

    An invocation of this method of the form out.append(csq, start, end) when csq is not null, behaves in exactly the same way as the invocation 

         out.append(csq.subSequence(start, end))
    Parameters:
    @param s the sequence to append.
    @param start The index of the first character in the subsequence
    @param end The index of the character following the last character in the subsequence
    Return:
    @return A reference to this Appendable
    Exceptions:
    @throws IndexOutOfBoundsException If start or end are negative, start is greater than end, or end is greater than csq.length()
    Since:
    @since 1.5
    Specified by:
    append from Appendable
    Override hierarchy:
    append from AbstractStringBuilder
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  • appendtop

    public synchronized StringBuffer append(Object obj)
    Appends the string representation of the Object argument.

    The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this sequence.

    Parameters:
    @param obj an Object.
    Return:
    @return a reference to this object.
    See:
    @see String.valueOf(java.lang.Object)
    @see StringBuffer.append(java.lang.String)
    Override hierarchy:
    append from AbstractStringBuilder
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  • appendtop

    public synchronized StringBuffer append(String str)
    Appends the specified string to this character sequence.

    The characters of the String argument are appended, in order, increasing the length of this sequence by the length of the argument. If str is null, then the four characters "null" are appended.

    Let n be the length of this character sequence just prior to execution of the append method. Then the character at index k in the new character sequence is equal to the character at index k in the old character sequence, if k is less than n; otherwise, it is equal to the character at index k-n in the argument str.

    Parameters:
    @param str a string.
    Return:
    @return a reference to this object.
    Override hierarchy:
    append from AbstractStringBuilder
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  • appendtop

    public synchronized StringBuffer append(StringBuffer sb)
    Appends the specified StringBuffer to this sequence.

    The characters of the StringBuffer argument are appended, in order, to the contents of this StringBuffer, increasing the length of this StringBuffer by the length of the argument. If sb is null, then the four characters "null" are appended to this StringBuffer.

    Let n be the length of the old character sequence, the one contained in the StringBuffer just prior to execution of the append method. Then the character at index k in the new character sequence is equal to the character at index k in the old character sequence, if k is less than n; otherwise, it is equal to the character at index k-n in the argument sb.

    This method synchronizes on this (the destination) object but does not synchronize on the source (sb).

    Parameters:
    @param sb the StringBuffer to append.
    Return:
    @return a reference to this object.
    Since:
    @since 1.4
    Override hierarchy:
    append from AbstractStringBuilder
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  • appendtop

    public synchronized StringBuffer append(boolean b)
    Appends the string representation of the boolean argument to the sequence.

    The argument is converted to a string as if by the method String.valueOf, and the characters of that string are then appended to this sequence.

    Parameters:
    @param b a boolean.
    Return:
    @return a reference to this object.
    See:
    @see String.valueOf(boolean)
    @see StringBuffer.append(java.lang.String)
    Override hierarchy:
    append from AbstractStringBuilder
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  • appendtop

    public synchronized StringBuffer append(char[] str)
    Appends the string representation of the char array argument to this sequence.

    The characters of the array argument are appended, in order, to the contents of this sequence. The length of this sequence increases by the length of the argument.

    The overall effect is exactly as if the argument were converted to a string by the method String.valueOf(char[]) and the characters of that string were then appended to this character sequence.

    Parameters:
    @param str the characters to be appended.
    Return:
    @return a reference to this object.
    Override hierarchy:
    append from AbstractStringBuilder
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  • appendtop

    public synchronized StringBuffer append(char[] str, int offset, int len)
    Appends the string representation of a subarray of the char array argument to this sequence.

    Characters of the char array str, starting at index offset, are appended, in order, to the contents of this sequence. The length of this sequence increases by the value of len.

    The overall effect is exactly as if the arguments were converted to a string by the method String.valueOf(char[], int, int) and the characters of that string were then appended to this character sequence.

    Parameters:
    @param str the characters to be appended.
    @param offset the index of the first char to append.
    @param len the number of chars to append.
    Return:
    @return a reference to this object.
    Override hierarchy:
    append from AbstractStringBuilder
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  • appendCodePointtop

    public synchronized StringBuffer appendCodePoint(int codePoint)
    Appends the string representation of the codePoint argument to this sequence.

    The argument is appended to the contents of this sequence. The length of this sequence increases by Character.charCount(codePoint).

    The overall effect is exactly as if the argument were converted to a char array by the method Character.toChars(int) and the character in that array were then appended to this character sequence.

    Parameters:
    @param codePoint a Unicode code point
    Return:
    @return a reference to this object.
    Since:
    @since 1.5
    Override hierarchy:
    appendCodePoint from AbstractStringBuilder
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  • capacitytop

    public synchronized int capacity()
    Returns the current capacity. The capacity is the amount of storage available for newly inserted characters, beyond which an allocation will occur.
    Return:
    @return the current capacity
    Override hierarchy:
    capacity from AbstractStringBuilder
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  • charAttop

    public synchronized char charAt(int index)
    Returns the char value at the specified index. An index ranges from zero to length() - 1. The first char value of the sequence is at index zero, the next at index one, and so on, as for array indexing.

    If the char value specified by the index is a surrogate, the surrogate value is returned.

    Parameters:
    @param index the index of the char value to be returned
    Return:
    @return the specified char value
    Exceptions:
    @throws IndexOutOfBoundsException if the index argument is negative or not less than length()
    See:
    @see StringBuffer.length()
    Specified by:
    charAt from CharSequence
    Override hierarchy:
    charAt from AbstractStringBuilder
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  • codePointAttop

    public synchronized int codePointAt(int index)
    Returns the character (Unicode code point) at the specified index. The index refers to char values (Unicode code units) and ranges from 0 to AbstractStringBuilder.length() - 1.

    If the char value specified at the given index is in the high-surrogate range, the following index is less than the length of this sequence, and the char value at the following index is in the low-surrogate range, then the supplementary code point corresponding to this surrogate pair is returned. Otherwise, the char value at the given index is returned.

    Parameters:
    @param index the index to the char values
    Return:
    @return the code point value of the character at the index
    Since:
    @since 1.5
    Override hierarchy:
    codePointAt from AbstractStringBuilder
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  • codePointBeforetop

    public synchronized int codePointBefore(int index)
    Returns the character (Unicode code point) before the specified index. The index refers to char values (Unicode code units) and ranges from 1 to AbstractStringBuilder.length().

    If the char value at (index - 1) is in the low-surrogate range, (index - 2) is not negative, and the char value at (index - 2) is in the high-surrogate range, then the supplementary code point value of the surrogate pair is returned. If the char value at index - 1 is an unpaired low-surrogate or a high-surrogate, the surrogate value is returned.

    Parameters:
    @param index the index following the code point that should be returned
    Return:
    @return the Unicode code point value before the given index.
    Since:
    @since 1.5
    Override hierarchy:
    codePointBefore from AbstractStringBuilder
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  • codePointCounttop

    public synchronized int codePointCount(int beginIndex, int endIndex)
    Returns the number of Unicode code points in the specified text range of this sequence. The text range begins at the specified beginIndex and extends to the char at index endIndex - 1. Thus the length (in chars) of the text range is endIndex-beginIndex. Unpaired surrogates within this sequence count as one code point each.
    Parameters:
    @param beginIndex the index to the first char of the text range.
    @param endIndex the index after the last char of the text range.
    Return:
    @return the number of Unicode code points in the specified text range
    Since:
    @since 1.5
    Override hierarchy:
    codePointCount from AbstractStringBuilder
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  • deletetop

    public synchronized StringBuffer delete(int start, int end)
    Removes the characters in a substring of this sequence. The substring begins at the specified start and extends to the character at index end - 1 or to the end of the sequence if no such character exists. If start is equal to end, no changes are made.
    Parameters:
    @param start The beginning index, inclusive.
    @param end The ending index, exclusive.
    Return:
    @return This object.
    Exceptions:
    @throws StringIndexOutOfBoundsException if start is negative, greater than length(), or greater than end.
    Since:
    @since 1.2
    Override hierarchy:
    delete from AbstractStringBuilder
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  • deleteCharAttop

    public synchronized StringBuffer deleteCharAt(int index)
    Removes the char at the specified position in this sequence. This sequence is shortened by one char.

    Note: If the character at the given index is a supplementary character, this method does not remove the entire character. If correct handling of supplementary characters is required, determine the number of chars to remove by calling Character.charCount(thisSequence.codePointAt(index)), where thisSequence is this sequence.

    Parameters:
    @param index Index of char to remove
    Return:
    @return This object.
    Exceptions:
    @throws StringIndexOutOfBoundsException if the index is negative or greater than or equal to length().
    Since:
    @since 1.2
    Override hierarchy:
    deleteCharAt from AbstractStringBuilder
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  • ensureCapacitytop

    public synchronized void ensureCapacity(int minimumCapacity)
    Ensures that the capacity is at least equal to the specified minimum. If the current capacity is less than the argument, then a new internal array is allocated with greater capacity. The new capacity is the larger of:
    • The minimumCapacity argument.
    • Twice the old capacity, plus 2.
    If the minimumCapacity argument is nonpositive, this method takes no action and simply returns.
    Parameters:
    @param minimumCapacity the minimum desired capacity.
    Override hierarchy:
    ensureCapacity from AbstractStringBuilder
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  • getCharstop

    public synchronized void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)
    Characters are copied from this sequence into the destination character array dst. The first character to be copied is at index srcBegin; the last character to be copied is at index srcEnd-1. The total number of characters to be copied is srcEnd-srcBegin. The characters are copied into the subarray of dst starting at index dstBegin and ending at index: 

     dstbegin + (srcEnd-srcBegin) - 1
    Parameters:
    @param srcBegin start copying at this offset.
    @param srcEnd stop copying at this offset.
    @param dst the array to copy the data into.
    @param dstBegin offset into dst.
    Exceptions:
    @throws NullPointerException if dst is null.
    @throws IndexOutOfBoundsException if any of the following is true:
    • srcBegin is negative
    • dstBegin is negative
    • the srcBegin argument is greater than the srcEnd argument.
    • srcEnd is greater than this.length().
    • dstBegin+srcEnd-srcBegin is greater than dst.length
    Override hierarchy:
    getChars from AbstractStringBuilder
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  • indexOftop

    public int indexOf(String str)
    Returns the index within this string of the first occurrence of the specified substring. The integer returned is the smallest value k such that: 
     this.toString().startsWith(str, k)
    is true.
    Parameters:
    @param str any string.
    Return:
    @return if the string argument occurs as a substring within this object, then the index of the first character of the first such substring is returned; if it does not occur as a substring, -1 is returned.
    Exceptions:
    @throws NullPointerException if str is null.
    Since:
    @since 1.4
    Override hierarchy:
    indexOf from AbstractStringBuilder
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  • indexOftop

    public synchronized int indexOf(String str, int fromIndex)
    Returns the index within this string of the first occurrence of the specified substring, starting at the specified index. The integer returned is the smallest value k for which: 
         k >= Math.min(fromIndex, str.length()) &&
                   this.toString().startsWith(str, k)
    If no such value of k exists, then -1 is returned.
    Parameters:
    @param str the substring for which to search.
    @param fromIndex the index from which to start the search.
    Return:
    @return the index within this string of the first occurrence of the specified substring, starting at the specified index.
    Exceptions:
    @throws NullPointerException if str is null.
    Since:
    @since 1.4
    Override hierarchy:
    indexOf from AbstractStringBuilder
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  • inserttop

    public synchronized StringBuffer insert(int offset, char c)
    Inserts the string representation of the char argument into this sequence.

    The second argument is inserted into the contents of this sequence at the position indicated by offset. The length of this sequence increases by one.

    The overall effect is exactly as if the argument were converted to a string by the method String.valueOf(char) and the character in that string were then inserted into this character sequence at the position indicated by offset.

    The offset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

    Parameters:
    @param offset the offset.
    @param c a char.
    Return:
    @return a reference to this object.
    Exceptions:
    @throws IndexOutOfBoundsException if the offset is invalid.
    See:
    @see StringBuffer.length()
    Override hierarchy:
    insert from AbstractStringBuilder
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  • inserttop

    public StringBuffer insert(int offset, double d)
    Inserts the string representation of the double argument into this sequence.

    The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this sequence at the indicated offset.

    The offset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

    Parameters:
    @param offset the offset.
    @param d a double.
    Return:
    @return a reference to this object.
    Exceptions:
    @throws StringIndexOutOfBoundsException if the offset is invalid.
    See:
    @see String.valueOf(double)
    @see StringBuffer.insert(int, java.lang.String)
    @see StringBuffer.length()
    Override hierarchy:
    insert from AbstractStringBuilder
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  • inserttop

    public StringBuffer insert(int offset, float f)
    Inserts the string representation of the float argument into this sequence.

    The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this sequence at the indicated offset.

    The offset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

    Parameters:
    @param offset the offset.
    @param f a float.
    Return:
    @return a reference to this object.
    Exceptions:
    @throws StringIndexOutOfBoundsException if the offset is invalid.
    See:
    @see String.valueOf(float)
    @see StringBuffer.insert(int, java.lang.String)
    @see StringBuffer.length()
    Override hierarchy:
    insert from AbstractStringBuilder
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  • inserttop

    public StringBuffer insert(int offset, int i)
    Inserts the string representation of the second int argument into this sequence.

    The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this sequence at the indicated offset.

    The offset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

    Parameters:
    @param offset the offset.
    @param i an int.
    Return:
    @return a reference to this object.
    Exceptions:
    @throws StringIndexOutOfBoundsException if the offset is invalid.
    See:
    @see String.valueOf(int)
    @see StringBuffer.insert(int, java.lang.String)
    @see StringBuffer.length()
    Override hierarchy:
    insert from AbstractStringBuilder
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  • inserttop

    public StringBuffer insert(int offset, long l)
    Inserts the string representation of the long argument into this sequence.

    The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this sequence at the position indicated by offset.

    The offset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

    Parameters:
    @param offset the offset.
    @param l a long.
    Return:
    @return a reference to this object.
    Exceptions:
    @throws StringIndexOutOfBoundsException if the offset is invalid.
    See:
    @see String.valueOf(long)
    @see StringBuffer.insert(int, java.lang.String)
    @see StringBuffer.length()
    Override hierarchy:
    insert from AbstractStringBuilder
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  • inserttop

    public StringBuffer insert(int dstOffset, CharSequence s)
    Inserts the specified CharSequence into this sequence.

    The characters of the CharSequence argument are inserted, in order, into this sequence at the indicated offset, moving up any characters originally above that position and increasing the length of this sequence by the length of the argument s.

    The result of this method is exactly the same as if it were an invocation of this object's insert(dstOffset, s, 0, s.length()) method.

    If s is null, then the four characters "null" are inserted into this sequence.

    Parameters:
    @param dstOffset the offset.
    @param s the sequence to be inserted
    Return:
    @return a reference to this object.
    Exceptions:
    @throws IndexOutOfBoundsException if the offset is invalid.
    Since:
    @since 1.5
    Override hierarchy:
    insert from AbstractStringBuilder
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  • inserttop

    public synchronized StringBuffer insert(int dstOffset, CharSequence s, int start, int end)
    Inserts a subsequence of the specified CharSequence into this sequence.

    The subsequence of the argument s specified by start and end are inserted, in order, into this sequence at the specified destination offset, moving up any characters originally above that position. The length of this sequence is increased by end - start.

    The character at index k in this sequence becomes equal to:

    • the character at index k in this sequence, if k is less than dstOffset
    • the character at index k+start-dstOffset in the argument s, if k is greater than or equal to dstOffset but is less than dstOffset+end-start
    • the character at index k-(end-start) in this sequence, if k is greater than or equal to dstOffset+end-start

    The dstOffset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

    The start argument must be nonnegative, and not greater than end.

    The end argument must be greater than or equal to start, and less than or equal to the length of s.

    If s is null, then this method inserts characters as if the s parameter was a sequence containing the four characters "null".

    Parameters:
    @param dstOffset the offset in this sequence.
    @param s the sequence to be inserted.
    @param start the starting index of the subsequence to be inserted.
    @param end the end index of the subsequence to be inserted.
    Return:
    @return a reference to this object.
    Exceptions:
    @throws IndexOutOfBoundsException if dstOffset is negative or greater than this.length(), or start or end are negative, or start is greater than end or end is greater than s.length()
    Since:
    @since 1.5
    Override hierarchy:
    insert from AbstractStringBuilder
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  • inserttop

    public synchronized StringBuffer insert(int offset, Object obj)
    Inserts the string representation of the Object argument into this character sequence.

    The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this sequence at the indicated offset.

    The offset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

    Parameters:
    @param offset the offset.
    @param obj an Object.
    Return:
    @return a reference to this object.
    Exceptions:
    @throws StringIndexOutOfBoundsException if the offset is invalid.
    See:
    @see String.valueOf(java.lang.Object)
    @see StringBuffer.insert(int, java.lang.String)
    @see StringBuffer.length()
    Override hierarchy:
    insert from AbstractStringBuilder
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  • inserttop

    public synchronized StringBuffer insert(int offset, String str)
    Inserts the string into this character sequence.

    The characters of the String argument are inserted, in order, into this sequence at the indicated offset, moving up any characters originally above that position and increasing the length of this sequence by the length of the argument. If str is null, then the four characters "null" are inserted into this sequence.

    The character at index k in the new character sequence is equal to:

    • the character at index k in the old character sequence, if k is less than offset
    • the character at index k-offset in the argument str, if k is not less than offset but is less than offset+str.length()
    • the character at index k-str.length() in the old character sequence, if k is not less than offset+str.length()

    The offset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

    Parameters:
    @param offset the offset.
    @param str a string.
    Return:
    @return a reference to this object.
    Exceptions:
    @throws StringIndexOutOfBoundsException if the offset is invalid.
    See:
    @see StringBuffer.length()
    Override hierarchy:
    insert from AbstractStringBuilder
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  • inserttop

    public StringBuffer insert(int offset, boolean b)
    Inserts the string representation of the boolean argument into this sequence.

    The second argument is converted to a string as if by the method String.valueOf, and the characters of that string are then inserted into this sequence at the indicated offset.

    The offset argument must be greater than or equal to 0, and less than or equal to the length of this sequence.

    Parameters:
    @param offset the offset.
    @param b a boolean.
    Return:
    @return a reference to this object.
    Exceptions:
    @throws StringIndexOutOfBoundsException if the offset is invalid.
    See:
    @see String.valueOf(boolean)
    @see StringBuffer.insert(int, java.lang.String)
    @see StringBuffer.length()
    Override hierarchy:
    insert from AbstractStringBuilder
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  • inserttop

    public synchronized StringBuffer insert(int offset, char[] str)
    Inserts the string representation of the char array argument into this sequence.

    The characters of the array argument are inserted into the contents of this sequence at the position indicated by offset. The length of this sequence increases by the length of the argument.

    The overall effect is exactly as if the argument were converted to a string by the method String.valueOf(char[]) and the characters of that string were then inserted into this character sequence at the position indicated by offset.

    Parameters:
    @param offset the offset.
    @param str a character array.
    Return:
    @return a reference to this object.
    Exceptions:
    @throws StringIndexOutOfBoundsException if the offset is invalid.
    Override hierarchy:
    insert from AbstractStringBuilder
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  • inserttop

    public synchronized StringBuffer insert(int index, char[] str, int offset, int len)
    Inserts the string representation of a subarray of the str array argument into this sequence. The subarray begins at the specified offset and extends len chars. The characters of the subarray are inserted into this sequence at the position indicated by index. The length of this sequence increases by len chars.
    Parameters:
    @param index position at which to insert subarray.
    @param str A char array.
    @param offset the index of the first char in subarray to be inserted.
    @param len the number of chars in the subarray to be inserted.
    Return:
    @return This object
    Exceptions:
    @throws StringIndexOutOfBoundsException if index is negative or greater than length(), or offset or len are negative, or (offset+len) is greater than str.length.
    Since:
    @since 1.2
    Override hierarchy:
    insert from AbstractStringBuilder
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  • lastIndexOftop

    public int lastIndexOf(String str)
    Returns the index within this string of the rightmost occurrence of the specified substring. The rightmost empty string "" is considered to occur at the index value this.length(). The returned index is the largest value k such that 
     this.toString().startsWith(str, k)
    is true.
    Parameters:
    @param str the substring to search for.
    Return:
    @return if the string argument occurs one or more times as a substring within this object, then the index of the first character of the last such substring is returned. If it does not occur as a substring, -1 is returned.
    Exceptions:
    @throws NullPointerException if str is null.
    Since:
    @since 1.4
    Override hierarchy:
    lastIndexOf from AbstractStringBuilder
    Related Links:
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  • lastIndexOftop

    public synchronized int lastIndexOf(String str, int fromIndex)
    Returns the index within this string of the last occurrence of the specified substring. The integer returned is the largest value k such that: 
         k <_ math.minfromindex="math.minfromindex" str.length="str.length" _="_" this.tostring.startswithstr="this.tostring.startswithstr" k="k" pre="pre">
    If no such value of k exists, then -1 is returned.
    Parameters:
    @param str the substring to search for.
    @param fromIndex the index to start the search from.
    Return:
    @return the index within this sequence of the last occurrence of the specified substring.
    Exceptions:
    @throws NullPointerException if str is null.
    Since:
    @since 1.4
    Override hierarchy:
    lastIndexOf from AbstractStringBuilder
    Related Links:
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  • lengthtop

    public synchronized int length()
    Returns the length of this character sequence. The length is the number of 16-bit chars in the sequence.
    Return:
    @return the number of chars in this sequence
    Specified by:
    length from CharSequence
    Override hierarchy:
    length from AbstractStringBuilder
    Related Links:
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  • offsetByCodePointstop

    public synchronized int offsetByCodePoints(int index, int codePointOffset)
    Returns the index within this sequence that is offset from the given index by codePointOffset code points. Unpaired surrogates within the text range given by index and codePointOffset count as one code point each.
    Parameters:
    @param index the index to be offset
    @param codePointOffset the offset in code points
    Return:
    @return the index within this sequence
    Since:
    @since 1.5
    Override hierarchy:
    offsetByCodePoints from AbstractStringBuilder
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  • readObjecttop

    private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException
    readObject is called to restore the state of the StringBuffer from a stream.
    Related Links:
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  • replacetop

    public synchronized StringBuffer replace(int start, int end, String str)
    Replaces the characters in a substring of this sequence with characters in the specified String. The substring begins at the specified start and extends to the character at index end - 1 or to the end of the sequence if no such character exists. First the characters in the substring are removed and then the specified String is inserted at start. (This sequence will be lengthened to accommodate the specified String if necessary.)
    Parameters:
    @param start The beginning index, inclusive.
    @param end The ending index, exclusive.
    @param str String that will replace previous contents.
    Return:
    @return This object.
    Exceptions:
    @throws StringIndexOutOfBoundsException if start is negative, greater than length(), or greater than end.
    Since:
    @since 1.2
    Override hierarchy:
    replace from AbstractStringBuilder
    Related Links:
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  • reversetop

    public synchronized StringBuffer reverse()
    Causes this character sequence to be replaced by the reverse of the sequence. If there are any surrogate pairs included in the sequence, these are treated as single characters for the reverse operation. Thus, the order of the high-low surrogates is never reversed. Let n be the character length of this character sequence (not the length in char values) just prior to execution of the reverse method. Then the character at index k in the new character sequence is equal to the character at index n-k-1 in the old character sequence.

    Note that the reverse operation may result in producing surrogate pairs that were unpaired low-surrogates and high-surrogates before the operation. For example, reversing "\uDC00\uD800" produces "\uD800\uDC00" which is a valid surrogate pair.

    Return:
    @return a reference to this object.
    Since:
    @since JDK1.0.2
    Override hierarchy:
    reverse from AbstractStringBuilder
    Related Links:
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  • setCharAttop

    public synchronized void setCharAt(int index, char ch)
    The character at the specified index is set to ch. This sequence is altered to represent a new character sequence that is identical to the old character sequence, except that it contains the character ch at position index.

    The index argument must be greater than or equal to 0, and less than the length of this sequence.

    Parameters:
    @param index the index of the character to modify.
    @param ch the new character.
    Exceptions:
    @throws IndexOutOfBoundsException if index is negative or greater than or equal to length().
    See:
    @see StringBuffer.length()
    Override hierarchy:
    setCharAt from AbstractStringBuilder
    Related Links:
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  • setLengthtop

    public synchronized void setLength(int newLength)
    Sets the length of the character sequence. The sequence is changed to a new character sequence whose length is specified by the argument. For every nonnegative index k less than newLength, the character at index k in the new character sequence is the same as the character at index k in the old sequence if k is less than the length of the old character sequence; otherwise, it is the null character '\u0000'. In other words, if the newLength argument is less than the current length, the length is changed to the specified length.

    If the newLength argument is greater than or equal to the current length, sufficient null characters ('\u0000') are appended so that length becomes the newLength argument.

    The newLength argument must be greater than or equal to 0.

    Parameters:
    @param newLength the new length
    Exceptions:
    @throws IndexOutOfBoundsException if the newLength argument is negative.
    See:
    @see StringBuffer.length()
    Override hierarchy:
    setLength from AbstractStringBuilder
    Related Links:
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  • subSequencetop

    public synchronized CharSequence subSequence(int start, int end)
    Returns a new CharSequence that is a subsequence of this sequence. The subsequence starts with the char value at the specified index and ends with the char value at index end - 1. The length (in chars) of the returned sequence is end - start, so if start == end then an empty sequence is returned.
    Parameters:
    @param start the start index, inclusive
    @param end the end index, exclusive
    Return:
    @return the specified subsequence
    Exceptions:
    @throws IndexOutOfBoundsException if start or end are negative, if end is greater than length(), or if start is greater than end
    Since:
    @since 1.4
    Specified by:
    subSequence from CharSequence
    Override hierarchy:
    subSequence from AbstractStringBuilder
    Related Links:
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  • substringtop

    public synchronized String substring(int start)
    Returns a new String that contains a subsequence of characters currently contained in this character sequence. The substring begins at the specified index and extends to the end of this sequence.
    Parameters:
    @param start The beginning index, inclusive.
    Return:
    @return The new string.
    Exceptions:
    @throws StringIndexOutOfBoundsException if start is less than zero, or greater than the length of this object.
    Since:
    @since 1.2
    Override hierarchy:
    substring from AbstractStringBuilder
    Related Links:
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  • substringtop

    public synchronized String substring(int start, int end)
    Returns a new String that contains a subsequence of characters currently contained in this sequence. The substring begins at the specified start and extends to the character at index end - 1.
    Parameters:
    @param start The beginning index, inclusive.
    @param end The ending index, exclusive.
    Return:
    @return The new string.
    Exceptions:
    @throws StringIndexOutOfBoundsException if start or end are negative or greater than length(), or start is greater than end.
    Since:
    @since 1.2
    Override hierarchy:
    substring from AbstractStringBuilder
    Related Links:
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  • toStringtop

    public synchronized String toString()
    Returns a string containing the characters in this sequence in the same order as this sequence. The length of the string will be the length of this sequence.
    Return:
    @return a string consisting of exactly this sequence of characters
    Specified by:
    toString from CharSequence
    Override hierarchy:
    toString from AbstractStringBuilder
    toString from Object
    Related Links:
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  • trimToSizetop

    public synchronized void trimToSize()
    Attempts to reduce storage used for the character sequence. If the buffer is larger than necessary to hold its current sequence of characters, then it may be resized to become more space efficient. Calling this method may, but is not required to, affect the value returned by a subsequent call to the AbstractStringBuilder.capacity() method.
    Since:
    @since 1.5
    Override hierarchy:
    trimToSize from AbstractStringBuilder
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  • writeObjecttop

    synchronized private void writeObject(ObjectOutputStream s) throws IOException
    readObject is called to restore the state of the StringBuffer from a stream.
    Related Links:
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Fields

  • serialPersistentFields

    static final private ObjectStreamField[] serialPersistentFields
    Serializable fields for StringBuffer.

  • serialVersionUID

    static final long serialVersionUID = 3388685877147921107
    use serialVersionUID from JDK 1.0.2 for interoperability