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jflight.tools
Class JfStringBuffer
java.lang.Objectjflight.tools.JfStringBuffer
- public final class JfStringBuffer
- extends java.lang.Object
A string buffer implements a mutable sequence of characters. A string buffer is like a java.lang.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 JfStringBuffer().append("a").append(4).append("c")
.toString()
The principal operations on a JfStringBuffer 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 JfStringBuffer,
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.
- Since:
- JDK1.0
- Version:
- 1.70, 12/03/01
| Field Summary | |
private int |
count
The count is the number of characters in the buffer. |
private static JfStringBuffer |
NULL
|
(package private) static long |
serialVersionUID
use serialVersionUID from JDK 1.0.2 for interoperability |
private boolean |
shared
A flag indicating whether the buffer is shared |
private char[] |
value
The value is used for character storage. |
| Constructor Summary | |
JfStringBuffer()
Constructs a string buffer with no characters in it and an initial capacity of 16 characters. |
|
JfStringBuffer(int length)
Constructs a string buffer with no characters in it and an initial capacity specified by the length argument. |
|
JfStringBuffer(java.lang.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. |
|
| Method Summary | |
JfStringBuffer |
append(boolean b)
Appends the string representation of the boolean
argument to the string buffer. |
JfStringBuffer |
append(char c)
Appends the string representation of the char
argument to this string buffer. |
JfStringBuffer |
append(char[] str)
Appends the string representation of the char array
argument to this string buffer. |
JfStringBuffer |
append(char[] str,
int offset,
int len)
Appends the string representation of a subarray of the char array argument to this string buffer. |
JfStringBuffer |
append(double d)
Appends the string representation of the double
argument to this string buffer. |
JfStringBuffer |
append(float f)
Appends the string representation of the float
argument to this string buffer. |
JfStringBuffer |
append(int i)
Appends the string representation of the int
argument to this string buffer. |
JfStringBuffer |
append(JfStringBuffer sb)
Appends the specified JfStringBuffer to this JfStringBuffer. |
JfStringBuffer |
append(long l)
Appends the string representation of the long
argument to this string buffer. |
JfStringBuffer |
append(java.lang.Object obj)
Appends the string representation of the Object
argument to this string buffer. |
JfStringBuffer |
append(java.lang.String str)
Appends the string to this string buffer. |
int |
capacity()
Returns the current capacity of the String buffer. |
char |
charAt(int index)
The specified character of the sequence currently represented by the string buffer, as indicated by the index argument,
is returned. |
private void |
copy()
Copies the buffer value. |
JfStringBuffer |
delete(int start,
int end)
Removes the characters in a substring of this JfStringBuffer. |
JfStringBuffer |
deleteCharAt(int index)
Removes the character at the specified position in this JfStringBuffer (shortening the JfStringBuffer
by one character). |
void |
ensureCapacity(int minimumCapacity)
Ensures that the capacity of the buffer is at least equal to the specified minimum. |
private void |
expandCapacity(int minimumCapacity)
This implements the expansion semantics of ensureCapacity but is unsynchronized for use internally by methods which are already synchronized. |
void |
getChars(int srcBegin,
int srcEnd,
char[] dst,
int dstBegin)
Characters are copied from this string buffer into the destination character array dst. |
(package private) char[] |
getValue()
|
int |
indexOf(java.lang.String str)
Returns the index within this string of the first occurrence of the specified substring. |
int |
indexOf(java.lang.String str,
int fromIndex)
Returns the index within this string of the first occurrence of the specified substring, starting at the specified index. |
JfStringBuffer |
insert(int offset,
boolean b)
Inserts the string representation of the boolean
argument into this string buffer. |
JfStringBuffer |
insert(int offset,
char c)
Inserts the string representation of the char
argument into this string buffer. |
JfStringBuffer |
insert(int offset,
char[] str)
Inserts the string representation of the char array
argument into this string buffer. |
JfStringBuffer |
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. |
JfStringBuffer |
insert(int offset,
double d)
Inserts the string representation of the double
argument into this string buffer. |
JfStringBuffer |
insert(int offset,
float f)
Inserts the string representation of the float
argument into this string buffer. |
JfStringBuffer |
insert(int offset,
int i)
Inserts the string representation of the second int
argument into this string buffer. |
JfStringBuffer |
insert(int offset,
long l)
Inserts the string representation of the long
argument into this string buffer. |
JfStringBuffer |
insert(int offset,
java.lang.Object obj)
Inserts the string representation of the Object
argument into this string buffer. |
JfStringBuffer |
insert(int offset,
java.lang.String str)
Inserts the string into this string buffer. |
int |
lastIndexOf(java.lang.String str)
Returns the index within this string of the rightmost occurrence of the specified substring. |
int |
lastIndexOf(java.lang.String str,
int fromIndex)
Returns the index within this string of the last occurrence of the specified substring. |
int |
length()
Returns the length (character count) of this string buffer. |
private void |
readObject(java.io.ObjectInputStream s)
readObject is called to restore the state of the JfStringBuffer from a stream. |
JfStringBuffer |
replace(int start,
int end,
java.lang.String str)
Replaces the characters in a substring of this JfStringBuffer
with characters in the specified String. |
JfStringBuffer |
reverse()
The character sequence contained in this string buffer is replaced by the reverse of the sequence. |
void |
setCharAt(int index,
char ch)
The character at the specified index of this string buffer is set to ch. |
void |
setLength(int newLength)
Sets the length of this String buffer. |
(package private) void |
setShared()
|
java.lang.String |
substring(int start)
Returns a new String that contains a subsequence of
characters currently contained in this JfStringBuffer.The
substring begins at the specified index and extends to the end of the
JfStringBuffer. |
java.lang.String |
substring(int start,
int end)
Returns a new String that contains a subsequence of
characters currently contained in this JfStringBuffer. |
java.lang.String |
toString()
Converts to a string representing the data in this string buffer. |
| Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
| Field Detail |
value
private char[] value
- The value is used for character storage.
count
private int count
- The count is the number of characters in the buffer.
shared
private boolean shared
- A flag indicating whether the buffer is shared
serialVersionUID
static final long serialVersionUID
- use serialVersionUID from JDK 1.0.2 for interoperability
- See Also:
- Constant Field Values
NULL
private static final JfStringBuffer NULL
| Constructor Detail |
JfStringBuffer
public JfStringBuffer()
- Constructs a string buffer with no characters in it and an
initial capacity of 16 characters.
JfStringBuffer
public JfStringBuffer(int length)
- Constructs a string buffer with no characters in it and an
initial capacity specified by the
lengthargument.
JfStringBuffer
public JfStringBuffer(java.lang.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
16plus the length of the string argument.
| Method Detail |
length
public int length()
- Returns the length (character count) of this string buffer.
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.
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.
ensureCapacity
public 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:
- The
minimumCapacityargument. - Twice the old capacity, plus
2.
minimumCapacityargument is nonpositive, this method takes no action and simply returns. - The
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.
setLength
public 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 thenewLengthargument is less than the current length of the string buffer, the string buffer is truncated to contain exactly the number of characters given by thenewLengthargument.If the
newLengthargument is greater than or equal to the current length, sufficient null characters ('\u0000') are appended to the string buffer so that length becomes thenewLengthargument.The
newLengthargument must be greater than or equal to0.
charAt
public char charAt(int index)
- The specified character of the sequence currently represented by
the string buffer, as indicated by the
indexargument, is returned. The first character of a string buffer is at index0, the next at index1, 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.
getChars
public 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 indexsrcBegin; the last character to be copied is at indexsrcEnd-1. The total number of characters to be copied issrcEnd-srcBegin. The characters are copied into the subarray ofdststarting at indexdstBeginand ending at index:dstbegin + (srcEnd-srcBegin) - 1
setCharAt
public 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 characterchat positionindex.The offset argument must be greater than or equal to
0, and less than the length of this string buffer.
append
public JfStringBuffer append(java.lang.Object obj)
- Appends the string representation of the
Objectargument 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.
append
public JfStringBuffer append(java.lang.String str)
- Appends the string to this string buffer.
The characters of the
Stringargument are appended, in order, to the contents of this string buffer, increasing the length of this string buffer by the length of the argument. Ifstrisnull, 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
appendmethod. 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 argumentstr.
append
public JfStringBuffer append(JfStringBuffer sb)
- Appends the specified JfStringBuffer to this
JfStringBuffer.
The characters of the JfStringBuffer argument are appended, in order, to the contents of this JfStringBuffer, increasing the length of this JfStringBuffer by the length of the argument. If sb is null, then the four characters "null" are appended to this JfStringBuffer.
Let n be the length of the old character sequence, the one contained in the JfStringBuffer 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.The method ensureCapacity is first called on this JfStringBuffer with the new buffer length as its argument. (This ensures that the storage of this JfStringBuffer is adequate to contain the additional characters being appended.)
- Since:
- 1.4
append
public JfStringBuffer append(char[] str)
- Appends the string representation of the
chararray 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 String.valueOf(char[])>
String.valueOf(char[])55 and the characters of that string were then appended 55 to thisJfStringBufferobject.
append
public JfStringBuffer append(char[] str, int offset, int len)
- Appends the string representation of a subarray of the
chararray argument to this string buffer.Characters of the character array
str, starting at indexoffset, are appended, in order, to the contents of this string buffer. The length of this string buffer increases by the value oflen.The overall effect is exactly as if the arguments were converted to a string by the method String.valueOf(char[],int,int)>
String.valueOf(char[],int,int)55 and the characters of that string were then appended 55 to thisJfStringBufferobject.
append
public JfStringBuffer append(boolean b)
- Appends the string representation of the
booleanargument 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.
append
public JfStringBuffer append(char c)
- Appends the string representation of the
charargument 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 String.valueOf(char)>
String.valueOf(char)55 and the character in that string were then appended 55 to thisJfStringBufferobject.
append
public JfStringBuffer append(int i)
- Appends the string representation of the
intargument 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.
append
public JfStringBuffer append(long l)
- Appends the string representation of the
longargument 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.
append
public JfStringBuffer append(float f)
- Appends the string representation of the
floatargument 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.
append
public JfStringBuffer append(double d)
- Appends the string representation of the
doubleargument 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.
delete
public JfStringBuffer delete(int start, int end)
- Removes the characters in a substring of this
JfStringBuffer. The substring begins at the specifiedstartand extends to the character at indexend - 1or to the end of theJfStringBufferif no such character exists. Ifstartis equal toend, no changes are made.- Since:
- 1.2
deleteCharAt
public JfStringBuffer deleteCharAt(int index)
- Removes the character at the specified position in this
JfStringBuffer(shortening theJfStringBufferby one character).- Since:
- 1.2
replace
public JfStringBuffer replace(int start, int end, java.lang.String str)
- Replaces the characters in a substring of this
JfStringBufferwith characters in the specifiedString. The substring begins at the specifiedstartand extends to the character at indexend - 1or to the end of theJfStringBufferif no such character exists. First the characters in the substring are removed and then the specifiedStringis inserted atstart. (TheJfStringBufferwill be lengthened to accommodate the specified String if necessary.)- Since:
- 1.2
substring
public java.lang.String substring(int start)
- Returns a new
Stringthat contains a subsequence of characters currently contained in thisJfStringBuffer.The substring begins at the specified index and extends to the end of theJfStringBuffer.- Since:
- 1.2
substring
public java.lang.String substring(int start, int end)
- Returns a new
Stringthat contains a subsequence of characters currently contained in thisJfStringBuffer. The substring begins at the specifiedstartand extends to the character at indexend - 1. An exception is thrown if- Since:
- 1.2
insert
public JfStringBuffer insert(int index, char[] str, int offset, int len)
- Inserts the string representation of a subarray of the
strarray argument into this string buffer. The subarray begins at the specifiedoffsetand extendslencharacters. The characters of the subarray are inserted into this string buffer at the position indicated byindex. The length of thisJfStringBufferincreases bylencharacters.- Since:
- 1.2
insert
public JfStringBuffer insert(int offset, java.lang.Object obj)
- Inserts the string representation of the
Objectargument 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.
insert
public JfStringBuffer insert(int offset, java.lang.String str)
- Inserts the string into this string buffer.
The characters of the
Stringargument 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. Ifstrisnull, 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 character at index k in the old character sequence, if
k is less than
offset - the character at index k
-offsetin the argumentstr, if k is not less thanoffsetbut is less thanoffset+str.length() - the character at index k
-str.length()in the old character sequence, if k is not less thanoffset+str.length()
The offset argument must be greater than or equal to
0, and less than or equal to the length of this string buffer. - the character at index k in the old character sequence, if
k is less than
insert
public JfStringBuffer insert(int offset, char[] str)
- Inserts the string representation of the
chararray 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 String.valueOf(char[])>
String.valueOf(char[])55 and the characters of that string were then inserted 55 into thisJfStringBufferobject at the position indicated byoffset.
insert
public JfStringBuffer insert(int offset, boolean b)
- Inserts the string representation of the
booleanargument 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.
insert
public JfStringBuffer insert(int offset, char c)
- Inserts the string representation of the
charargument 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 String.valueOf(char)>
String.valueOf(char)55 and the character in that string were then inserted 55 into thisJfStringBufferobject at the position indicated byoffset.The offset argument must be greater than or equal to
0, and less than or equal to the length of this string buffer.
insert
public JfStringBuffer insert(int offset, int i)
- Inserts the string representation of the second
intargument 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.
insert
public JfStringBuffer insert(int offset, long l)
- Inserts the string representation of the
longargument 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 byoffset.The offset argument must be greater than or equal to
0, and less than or equal to the length of this string buffer.
insert
public JfStringBuffer insert(int offset, float f)
- Inserts the string representation of the
floatargument 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.
insert
public JfStringBuffer insert(int offset, double d)
- Inserts the string representation of the
doubleargument 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.
indexOf
public int indexOf(java.lang.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:
isthis.toString().startsWith(str, k)
true.- Since:
- 1.4
indexOf
public int indexOf(java.lang.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:
If no such value of k exists, then -1 is returned.k >= Math.min(fromIndex, str.length()) && this.toString().startsWith(str, k)- Since:
- 1.4
lastIndexOf
public int lastIndexOf(java.lang.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
is true.this.toString().startsWith(str, k)
- Since:
- 1.4
lastIndexOf
public int lastIndexOf(java.lang.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:
If no such value of k exists, then -1 is returned.k <= Math.min(fromIndex, str.length()) && this.toString().startsWith(str, k)- Since:
- 1.4
reverse
public JfStringBuffer 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
reversemethod. 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.- Since:
- JDK1.0.2
toString
public java.lang.String toString()
- Converts to a string representing the data in this string buffer.
A new
Stringobject is allocated and initialized to contain the character sequence currently represented by this string buffer. ThisStringis then returned. Subsequent changes to the string buffer do not affect the contents of theString.Implementation advice: This method can be coded so as to create a new
Stringobject 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.
setShared
final void setShared()
getValue
final char[] getValue()
readObject
private void readObject(java.io.ObjectInputStream s) throws java.io.IOException, java.lang.ClassNotFoundException
- readObject is called to restore the state of the JfStringBuffer from
a stream.
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SUMMARY: JAVADOC | SOURCE | DOWNLOAD | NESTED | FIELD | CONSTR | METHOD |
DETAIL: FIELD | CONSTR | METHOD | ||||||||