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Class buildtools.PortableStringBuffer

java.lang.Object
   |
   +----buildtools.PortableStringBuffer

public final class PortableStringBuffer
extends Object
implements Serializable
A string buffer implements a mutable sequence of characters. A string buffer is like a {@link 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.

String buffers are used by the compiler to implement the binary string concatenation operator +. For example, the code:

     x = "a" + 4 + "c"
 

is compiled to the equivalent of:

     x = new StringBuffer().append("a").append(4).append("c")
                           .toString()
 
which creates a new string buffer (initially empty), appends the string representation of each operand to the string buffer in turn, and then converts the contents of the string buffer to a string. Overall, this avoids creating many temporary strings.

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).

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.

Version:
1.45, 10/27/98
Author:
Arthur van Hoff
See Also:
ByteArrayOutputStream, String

Variable Index

 o count
The count is the number of characters in the buffer.
 o serialVersionUID
use serialVersionUID from JDK 1.0.2 for interoperability
 o shared
A flag indicating whether the buffer is shared
 o value
The value is used for character storage.

Constructor Index

 o PortableStringBuffer()
Constructs a string buffer with no characters in it and an initial capacity of 16 characters.
 o PortableStringBuffer(int)
Constructs a string buffer with no characters in it and an initial capacity specified by the length argument.
 o PortableStringBuffer(String)
Constructs a string buffer so that it represents the same sequence of characters as the string argument; in other words, the initial contents of the string buffer is a copy of the argument string.

Method Index

 o append(boolean)
Appends the string representation of the boolean argument to the string buffer.
 o append(char)
Appends the string representation of the char argument to this string buffer.
 o append(char[])
Appends the string representation of the char array argument to this string buffer.
 o append(char[], int, int)
Appends the string representation of a subarray of the char array argument to this string buffer.
 o append(double)
Appends the string representation of the double argument to this string buffer.
 o append(float)
Appends the string representation of the float argument to this string buffer.
 o append(int)
Appends the string representation of the int argument to this string buffer.
 o append(long)
Appends the string representation of the long argument to this string buffer.
 o append(Object)
Appends the string representation of the Object argument to this string buffer.
 o append(String)
Appends the string to this string buffer.
 o capacity()
Returns the current capacity of the String buffer.
 o charAt(int)
The specified character of the sequence currently represented by the string buffer, as indicated by the index argument, is returned.
 o copy()
Copies the buffer value.
 o delete(int, int)
Removes the characters in a substring of this PortableStringBuffer.
 o deleteCharAt(int)
Removes the character at the specified position in this PortableStringBuffer (shortening the PortableStringBuffer by one character).
 o ensureCapacity(int)
Ensures that the capacity of the buffer is at least equal to the specified minimum.
 o expandCapacity(int)
This implements the expansion semantics of ensureCapacity but is unsynchronized for use internally by methods which are already synchronized.
 o getChars(int, int, char[], int)
Characters are copied from this string buffer into the destination character array dst.
 o getValue()
 o insert(int, boolean)
Inserts the string representation of the boolean argument into this string buffer.
 o insert(int, char)
Inserts the string representation of the char argument into this string buffer.
 o insert(int, char[])
Inserts the string representation of the char array argument into this string buffer.
 o insert(int, char[], int, int)
Inserts the string representation of a subarray of the str array argument into this string buffer.
 o insert(int, double)
Inserts the string representation of the double argument into this string buffer.
 o insert(int, float)
Inserts the string representation of the float argument into this string buffer.
 o insert(int, int)
Inserts the string representation of the second int argument into this string buffer.
 o insert(int, long)
Inserts the string representation of the long argument into this string buffer.
 o insert(int, Object)
Inserts the string representation of the Object argument into this string buffer.
 o insert(int, String)
Inserts the string into this string buffer.
 o length()
Returns the length (character count) of this string buffer.
 o readObject(ObjectInputStream)
readObject is called to restore the state of the PortableStringBuffer from a stream.
 o replace(int, int, String)
Replaces the characters in a substring of this PortableStringBuffer with characters in the specified String.
 o reverse()
The character sequence contained in this string buffer is replaced by the reverse of the sequence.
 o setCharAt(int, char)
The character at the specified index of this string buffer is set to ch.
 o setLength(int)
Sets the length of this String buffer.
 o setShared()
 o substring(int)
Returns a new String that contains a subsequence of characters currently contained in this PortableStringBuffer.The substring begins at the specified index and extends to the end of the PortableStringBuffer.
 o substring(int, int)
Returns a new String that contains a subsequence of characters currently contained in this PortableStringBuffer.
 o toString()
Converts to a string representing the data in this string buffer.

Variables

 o value
 private char value[]
The value is used for character storage.

 o count
 private int count
The count is the number of characters in the buffer.

 o shared
 private boolean shared
A flag indicating whether the buffer is shared

 o serialVersionUID
 static final long serialVersionUID
use serialVersionUID from JDK 1.0.2 for interoperability

Constructors

 o PortableStringBuffer
 public PortableStringBuffer()
Constructs a string buffer with no characters in it and an initial capacity of 16 characters.

 o PortableStringBuffer
 public PortableStringBuffer(int length)
Constructs a string buffer with no characters in it and an initial capacity specified by the length argument.

Parameters:
length - the initial capacity.
Throws: NegativeArraySizeException
if the length argument is less than 0.
 o PortableStringBuffer
 public PortableStringBuffer(String str)
Constructs a string buffer so that it represents the same sequence of characters as the string argument; in other words, the initial contents of the string buffer is a copy of the argument string. The initial capacity of the string buffer is 16 plus the length of the string argument.

Parameters:
str - the initial contents of the buffer.

Methods

 o length
 public int length()
Returns the length (character count) of this string buffer.

Returns:
the length of the sequence of characters currently represented by this string buffer.
 o capacity
 public int capacity()
Returns the current capacity of the String buffer. The capacity is the amount of storage available for newly inserted characters; beyond which an allocation will occur.

Returns:
the current capacity of this string buffer.
 o copy
 private final void copy()
Copies the buffer value. This is normally only called when shared is true. It should only be called from a synchronized method.

 o ensureCapacity
 public synchronized void ensureCapacity(int minimumCapacity)
Ensures that the capacity of the buffer is at least equal to the specified minimum. If the current capacity of this string buffer is less than the argument, then a new internal buffer is allocated with greater capacity. The new capacity is the larger of: If the minimumCapacity argument is nonpositive, this method takes no action and simply returns.

Parameters:
minimumCapacity - the minimum desired capacity.
 o expandCapacity
 private void expandCapacity(int minimumCapacity)
This implements the expansion semantics of ensureCapacity but is unsynchronized for use internally by methods which are already synchronized.

See Also:
ensureCapacity
 o setLength
 public synchronized void setLength(int newLength)
Sets the length of this String buffer. This string buffer is altered to represent 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 ''. In other words, if the newLength argument is less than the current length of the string buffer, the string buffer is truncated to contain exactly the number of characters given by the newLength argument.

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

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

Parameters:
newLength - the new length of the buffer.
Throws: IndexOutOfBoundsException
if the newLength argument is negative.
See Also:
length
 o charAt
 public synchronized char charAt(int index)
The specified character of the sequence currently represented by the string buffer, as indicated by the index argument, is returned. The first character of a string buffer is at index 0, the next at index 1, and so on, for array indexing.

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

Parameters:
index - the index of the desired character.
Returns:
the character at the specified index of this string buffer.
Throws: IndexOutOfBoundsException
if index is negative or greater than or equal to length().
See Also:
length
 o getChars
 public synchronized void getChars(int srcBegin,
                                   int srcEnd,
                                   char dst[],
                                   int dstBegin)
Characters are copied from this string buffer 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:
srcBegin - start copying at this offset in the string buffer.
srcEnd - stop copying at this offset in the string buffer.
dst - the array to copy the data into.
dstBegin - offset into dst.
Throws: NullPointerException
if dst is null.
Throws: IndexOutOfBoundsException
if any of the following is true:
  • srcBegin is negative
  • the srcBeing argument is greater than the srcEnd argument.
  • srcEnd is greater than this.length(), the current length of this string buffer.
  • dstBegin+srcEnd-srcBegin is greater than dst.length
 o setCharAt
 public synchronized void setCharAt(int index,
                                    char ch)
The character at the specified index of this string buffer is set to ch. The string buffer 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 offset argument must be greater than or equal to 0, and less than the length of this string buffer.

Parameters:
index - the index of the character to modify.
ch - the new character.
Throws: IndexOutOfBoundsException
if index is negative or greater than or equal to length().
See Also:
length
 o append
 public synchronized PortableStringBuffer append(Object obj)
Appends the string representation of the Object argument to this string buffer.

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 buffer.

Parameters:
obj - an Object.
Returns:
a reference to this PortableStringBuffer object.
See Also:
valueOf, append
 o append
 public synchronized PortableStringBuffer append(String str)
Appends the string to this string buffer.

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

Let n be the length of the old character sequence, the one contained in the string buffer 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:
str - a string.
Returns:
a reference to this StringBuffer.
 o append
 public synchronized PortableStringBuffer append(char str[])
Appends the string representation of the char array argument to this string buffer.

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

The overall effect is exactly as if the argument were converted to a string by the method {@link String#valueOf(char[])} and the characters of that string were then {@link #append(String) appended} to this PortableStringBuffer object.

Parameters:
str - the characters to be appended.
Returns:
a reference to this PortableStringBuffer object.
 o append
 public synchronized PortableStringBuffer append(char str[],
                                                 int offset,
                                                 int len)
Appends the string representation of a subarray of the char array argument to this string buffer.

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

The overall effect is exactly as if the arguments were converted to a string by the method {@link String#valueOf(char[],int,int)} and the characters of that string were then {@link #append(String) appended} to this PortableStringBuffer object.

Parameters:
str - the characters to be appended.
offset - the index of the first character to append.
len - the number of characters to append.
Returns:
a reference to this PortableStringBuffer object.
 o append
 public PortableStringBuffer append(boolean b)
Appends the string representation of the boolean argument to the string buffer.

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 buffer.

Parameters:
b - a boolean.
Returns:
a reference to this PortableStringBuffer.
See Also:
valueOf, append
 o append
 public synchronized PortableStringBuffer append(char c)
Appends the string representation of the char argument to this string buffer.

The argument is appended to the contents of this string buffer. The length of this string buffer increases by 1.

The overall effect is exactly as if the argument were converted to a string by the method {@link String#valueOf(char)} and the character in that string were then {@link #append(String) appended} to this PortableStringBuffer object.

Parameters:
ch - a char.
Returns:
a reference to this PortableStringBuffer object.
 o append
 public PortableStringBuffer append(int i)
Appends the string representation of the int argument to this string buffer.

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 buffer.

Parameters:
i - an int.
Returns:
a reference to this PortableStringBuffer object.
See Also:
valueOf, append
 o append
 public PortableStringBuffer append(long l)
Appends the string representation of the long argument to this string buffer.

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 buffer.

Parameters:
l - a long.
Returns:
a referenct to this PortableStringBuffer object.
See Also:
valueOf, append
 o append
 public PortableStringBuffer append(float f)
Appends the string representation of the float argument to this string buffer.

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 buffer.

Parameters:
f - a float.
Returns:
a reference to this StringBuffer object.
See Also:
valueOf, append
 o append
 public PortableStringBuffer append(double d)
Appends the string representation of the double argument to this string buffer.

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 buffer.

Parameters:
d - a double.
Returns:
a reference to this PortableStringBuffer object.
See Also:
valueOf, append
 o delete
 public synchronized PortableStringBuffer delete(int start,
                                                 int end)
Removes the characters in a substring of this PortableStringBuffer. The substring begins at the specified start and extends to the character at index end - 1 or to the end of the PortableStringBuffer if no such character exists. If start is equal to end, no changes are made.

Parameters:
start - The beginning index, inclusive.
end - The ending index, exclusive.
Returns:
This string buffer.
Throws: StringIndexOutOfBoundsException
if start is negative, greater than length(), or greater than end.
 o deleteCharAt
 public synchronized PortableStringBuffer deleteCharAt(int index)
Removes the character at the specified position in this PortableStringBuffer (shortening the PortableStringBuffer by one character).

Parameters:
index - Index of character to remove
Returns:
This string buffer.
Throws: StringIndexOutOfBoundsException
if the index is negative or greater than or equal to length().
 o replace
 public synchronized PortableStringBuffer replace(int start,
                                                  int end,
                                                  String str)
Replaces the characters in a substring of this PortableStringBuffer 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 PortableStringBuffer if no such character exists. First the characters in the substring are removed and then the specified String is inserted at start. (The PortableStringBuffer will be lengthened to accommodate the specified String if necessary.)

Parameters:
start - The beginning index, inclusive.
end - The ending index, exclusive.
str - String that will replace previous contents.
Returns:
This string buffer.
Throws: StringIndexOutOfBoundsException
if start is negative, greater than length(), or greater than end.
 o substring
 public String substring(int start)
Returns a new String that contains a subsequence of characters currently contained in this PortableStringBuffer.The substring begins at the specified index and extends to the end of the PortableStringBuffer.

Parameters:
start - The beginning index, inclusive.
Returns:
The new string.
Throws: StringIndexOutOfBoundsException
if start is less than zero, or greater than the length of this PortableStringBuffer.
 o substring
 public synchronized String substring(int start,
                                      int end)
Returns a new String that contains a subsequence of characters currently contained in this PortableStringBuffer. The substring begins at the specified start and extends to the character at index end - 1. An exception is thrown if

Parameters:
start - The beginning index, inclusive.
end - The ending index, exclusive.
Returns:
The new string.
Throws: StringIndexOutOfBoundsException
if start or end are negative or greater than length(), or start is greater than end.
 o insert
 public synchronized PortableStringBuffer insert(int index,
                                                 char str[],
                                                 int offset,
                                                 int len)
Inserts the string representation of a subarray of the str array argument into this string buffer. The subarray begins at the specified offset and extends len characters. The characters of the subarray are inserted into this string buffer at the position indicated by index. The length of this PortableStringBuffer increases by len characters.

Parameters:
index - position at which to insert subarray.
str - A character array.
offset - the index of the first character in subarray to to be inserted.
len - the number of characters in the subarray to to be inserted.
Returns:
This string buffer.
Throws: StringIndexOutOfBoundsException
if index is negative or greater than length(), or offset or len are negative, or (offset+len) is greater than str.length.
 o insert
 public synchronized PortableStringBuffer insert(int offset,
                                                 Object obj)
Inserts the string representation of the Object argument into this string buffer.

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 string buffer 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 string buffer.

Parameters:
offset - the offset.
b - an Object.
Returns:
a reference to this PortableStringBuffer object.
Throws: StringIndexOutOfBoundsException
if the offset is invalid.
See Also:
valueOf, insert, length
 o insert
 public synchronized PortableStringBuffer insert(int offset,
                                                 String str)
Inserts the string into this string buffer.

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

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

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

Parameters:
offset - the offset.
str - a string.
Returns:
a reference to this PortableStringBuffer object.
Throws: StringIndexOutOfBoundsException
if the offset is invalid.
See Also:
length
 o insert
 public synchronized PortableStringBuffer insert(int offset,
                                                 char str[])
Inserts the string representation of the char array argument into this string buffer.

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

The overall effect is exactly as if the argument were converted to a string by the method {@link String#valueOf(char[])} and the characters of that string were then {@link #insert(int,String) inserted} into this PortableStringBuffer object at the position indicated by offset.

Parameters:
offset - the offset.
ch - a character array.
Returns:
a reference to this PortableStringBuffer object.
Throws: StringIndexOutOfBoundsException
if the offset is invalid.
 o insert
 public PortableStringBuffer insert(int offset,
                                    boolean b)
Inserts the string representation of the boolean argument into this string buffer.

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 string buffer 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 string buffer.

Parameters:
offset - the offset.
b - a boolean.
Returns:
a reference to this PortableStringBuffer object.
Throws: StringIndexOutOfBoundsException
if the offset is invalid.
See Also:
valueOf, insert, length
 o insert
 public synchronized PortableStringBuffer insert(int offset,
                                                 char c)
Inserts the string representation of the char argument into this string buffer.

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

The overall effect is exactly as if the argument were converted to a string by the method {@link String#valueOf(char)} and the character in that string were then {@link #insert(int, String) inserted} into this PortableStringBuffer object 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 string buffer.

Parameters:
offset - the offset.
ch - a char.
Returns:
a reference to this PortableStringBuffer object.
Throws: StringIndexOutOfBoundsException
if the offset is invalid.
See Also:
length
 o insert
 public PortableStringBuffer insert(int offset,
                                    int i)
Inserts the string representation of the second int argument into this string buffer.

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 string buffer 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 string buffer.

Parameters:
offset - the offset.
b - an int.
Returns:
a reference to this PortableStringBuffer object.
Throws: StringIndexOutOfBoundsException
if the offset is invalid.
See Also:
valueOf, insert, length
 o insert
 public PortableStringBuffer insert(int offset,
                                    long l)
Inserts the string representation of the long argument into this string buffer.

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 string buffer 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 string buffer.

Parameters:
offset - the offset.
b - a long.
Returns:
a reference to this PortableStringBuffer object.
Throws: StringIndexOutOfBoundsException
if the offset is invalid.
See Also:
valueOf, insert, length
 o insert
 public PortableStringBuffer insert(int offset,
                                    float f)
Inserts the string representation of the float argument into this string buffer.

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 string buffer 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 string buffer.

Parameters:
offset - the offset.
b - a float.
Returns:
a reference to this PortableStringBuffer object.
Throws: StringIndexOutOfBoundsException
if the offset is invalid.
See Also:
valueOf, insert, length
 o insert
 public PortableStringBuffer insert(int offset,
                                    double d)
Inserts the string representation of the double argument into this string buffer.

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 string buffer 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 string buffer.

Parameters:
offset - the offset.
b - a double.
Returns:
a reference to this PortableStringBuffer object.
Throws: StringIndexOutOfBoundsException
if the offset is invalid.
See Also:
valueOf, insert, length
 o reverse
 public synchronized PortableStringBuffer reverse()
The character sequence contained in this string buffer is replaced by the reverse of the sequence.

Let n be the length of the old character sequence, the one contained in the string buffer 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.

Returns:
a reference to this object..
 o toString
 public String toString()
Converts to a string representing the data in this string buffer. A new String object is allocated and initialized to contain the character sequence currently represented by this string buffer. This String is then returned. Subsequent changes to the string buffer do not affect the contents of the String.

Implementation advice: This method can be coded so as to create a new String object without allocating new memory to hold a copy of the character sequence. Instead, the string can share the memory used by the string buffer. Any subsequent operation that alters the content or capacity of the string buffer must then make a copy of the internal buffer at that time. This strategy is effective for reducing the amount of memory allocated by a string concatenation operation when it is implemented using a string buffer.

Returns:
a string representation of the string buffer.
Overrides:
toString in class Object
 o setShared
 final void setShared()
 o getValue
 final char[] getValue()
 o readObject
 private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException
readObject is called to restore the state of the PortableStringBuffer from a stream.


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