в 17:44, 31 мая 2010

2010-05-31T17:44:27Z

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2010-05-31T15:30:08Z

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== Adding String to a StringBuffer Object ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer newString = new StringBuffer("abcde1234567890");

newString.append("saves nine");

System.out.println(newString);

}
}</source>



<pre class=codeResult>abcde1234567890saves nine</pre>

== Appending a subset of the elements from a char array ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer buf = new StringBuffer("::");
char[] text = { "i", "s", " ", "e", "x", "a", "c", "t", "l", "y"};
buf.append(text, 2, 8);
System.out.println(buf);
}
}</source>



<pre class=codeResult>:: exactly</pre>

== Appending a Substring: append part of the aString object to the buf object ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer buf = new StringBuffer("1234567890");
String aString = "abcdefghijk";
buf.append(aString, 3, 4);

System.out.println(buf);
}
}</source>



<pre class=codeResult>1234567890d</pre>

== Appending Basic Types: long, double ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer buf = new StringBuffer("The number is ");
long number = 999;
buf.append(number);
buf.append(12.34);
System.out.println(buf);
}
}</source>



<pre class=codeResult>The number is 99912.34</pre>

== Calling append() method to construct a StringBuffer object ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer proverb = new StringBuffer(); // Capacity is 16
proverb.append("A").append("B").append("C").append("D").append("E");
System.out.println(proverb);
}
}</source>



<pre class=codeResult>ABCDE</pre>

== Changing a single character in a StringBuffer object ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer phrase = new StringBuffer("one two three four");
phrase.setCharAt(3, "Z");
System.out.println(phrase);
}
}</source>



<pre class=codeResult>oneZtwo three four</pre>

== Changing the StringBufer Length for a StringBuffer Object ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer newString = new StringBuffer("abcde1234567890");

System.out.println(newString.capacity());
System.out.println(newString.length());
System.out.println(newString);

newString.setLength(8);
System.out.println(newString.capacity());
System.out.println(newString.length());
System.out.println(newString);

}
}</source>



<pre class=codeResult>31
15
abcde1234567890
31
8
abcde123</pre>

== Check the capacity of StringBuilder object ==



<source lang="java">
public class Main {
public static void main(String[] a) {
StringBuilder builder1 = new StringBuilder();
StringBuilder builder2 = new StringBuilder(0);
StringBuilder builder3 = new StringBuilder(100);
System.out.println(builder1.capacity());
System.out.println(builder2.capacity());
System.out.println(builder3.capacity());
}
}
/*
16
0
100
*/</source>



== Convert digit to character with Character.forDigit ==



<source lang="java">
public class MainClass {
public static void main(String args[]) {
System.out.printf("Convert digit to character: %s\n", Character.forDigit(12, 2));
}
}</source>



== Creating a StringBuffer object with a specific value for the capacity ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer newString = new StringBuffer(50);

System.out.println(newString.capacity());
}
}</source>



<pre class=codeResult>50</pre>

== Creating a String Object From a StringBuffer Object ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer palindrome = new StringBuffer("so many dynamos");

String aString = palindrome.toString();
System.out.println(aString);
}
}</source>



<pre class=codeResult>so many dynamos</pre>

== Deletes text from the StringBuilder object ==



<source lang="java">
public class Main {
public static void main(String[] a) {
StringBuilder builder = new StringBuilder("Line 1\n");
builder.append("Line 3\n");
builder.insert(0, "Line 2\n");
System.out.println(builder.toString());
builder = builder.delete(2, 6);
System.out.println(builder.toString());
}
}
/*
Line 2
Line 1
Line 3
Li
Line 1
Line 3
*/</source>



== Extracting Characters From a Mutable String: charAt() and getChars() methods ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer phrase = new StringBuffer("one two three four");

System.out.println(phrase.charAt(5));

char[] textArray = new char[3];
phrase.getChars(9, 12, textArray, 0);
for(char ch: textArray){
System.out.println(ch);

}
}
}</source>



<pre class=codeResult>w
h
r
e</pre>

== Finding the Position of a Substring ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer phrase = new StringBuffer("one two three four");
int position = phrase.lastIndexOf("three");
System.out.println(position);
}
}</source>



<pre class=codeResult>8</pre>

== Inserting Strings ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer phrase = new StringBuffer("one two three four");
phrase.insert(4, "old");

System.out.println(phrase);

}
}</source>



<pre class=codeResult>one oldtwo three four</pre>

== Remove substring from StringBuilder ==



<source lang="java">
public class Main {
public static void main(String[] args) {
StringBuilder lipsum = new StringBuilder("Lorem ipsum dolor sit amet.");
System.out.println("lipsum = " + lipsum.toString());
lipsum.delete(0, 28);
System.out.println("lipsum = " + lipsum.toString());
lipsum.deleteCharAt(lipsum.length() - 1);
System.out.println("lipsum = " + lipsum.toString());
}
}</source>



== Removing several characters from a StringBuffer object ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer phrase = new StringBuffer("one two three four");
phrase.delete(5, 9);
System.out.println(phrase);
}
}</source>



<pre class=codeResult>one three four</pre>

== Replacing a Substring in the Buffer ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer phrase = new StringBuffer("one two three four");
String substring = "two";
String replacement = "twenty";
int position = phrase.lastIndexOf(substring); // Find start of "two"
phrase.replace(position, position + substring.length(), replacement);

System.out.println(phrase);
}
}</source>



<pre class=codeResult>one twenty three four</pre>

== Reversing the sequence of characters in a StringBuffer object with the reverse() method ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer palindrome = new StringBuffer("so many dynamos");

palindrome.reverse();
System.out.println(palindrome);
}
}</source>



<pre class=codeResult>somanyd ynam os</pre>

== Specifying the index position in the buffer where the search is to start ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer phrase = new StringBuffer("one two three four");
int position = phrase.lastIndexOf("three", 6);
System.out.println(position);
}
}</source>



<pre class=codeResult>-1</pre>

== StringBuffer and StringBuilder ==

<OL><LI>Using StringBuffer and StringBuilder to transform strings frequently: adding,
deleting, or replacing substrings in a string.</LI><LI>Operations will be faster and easier using mutable objects.</LI><LI>All the operations in the context of StringBuffer are available with the
StringBuilder class, which will be faster but not thread-safe.</LI></OL>

== StringBuffer methods charAt, setCharAt, getChars and reverse ==



<source lang="java">
public class MainClass
{
public static void main( String args[] )
{
StringBuffer buffer = new StringBuffer( "hello there" );
System.out.printf( "buffer = %s\n", buffer.toString() );
System.out.printf( "Character at 0: %s\nCharacter at 4: %s\n\n",
buffer.charAt( 0 ), buffer.charAt( 4 ) );
char charArray[] = new char[ buffer.length() ];
buffer.getChars( 0, buffer.length(), charArray, 0 );
System.out.print( "The characters are: " );
for ( char character : charArray )
System.out.print( character );
buffer.setCharAt( 0, "H" );
buffer.setCharAt( 6, "T" );
System.out.printf( "\n\nbuf = %s", buffer.toString() );
buffer.reverse();
System.out.printf( "\n\nbuf = %s\n", buffer.toString() );
}
}</source>



== StringBuffer methods insert, delete and deleteCharAt ==



<source lang="java">
public class MainClass {
public static void main(String args[]) {
Object objectRef = "hello";
String string = "goodbye";
char charArray[] = { "a", "b", "c", "d", "e", "f" };
boolean booleanValue = true;
char characterValue = "K";
int integerValue = 7;
long longValue = 10000000;
float floatValue = 2.5f;
double doubleValue = 33.3;
StringBuffer buffer = new StringBuffer();
buffer.insert(0, objectRef);
buffer.insert(0, " ");
buffer.insert(0, string);
buffer.insert(0, " ");
buffer.insert(0, charArray);
buffer.insert(0, " ");
buffer.insert(0, charArray, 3, 3);
buffer.insert(0, " ");
buffer.insert(0, booleanValue);
buffer.insert(0, " ");
buffer.insert(0, characterValue);
buffer.insert(0, " ");
buffer.insert(0, integerValue);
buffer.insert(0, " ");
buffer.insert(0, longValue);
buffer.insert(0, " ");
buffer.insert(0, floatValue);
buffer.insert(0, " ");
buffer.insert(0, doubleValue);
System.out.printf("buffer after inserts:\n%s\n\n", buffer.toString());
buffer.deleteCharAt(10);
buffer.delete(2, 6);
System.out.printf("buffer after deletes:\n%s\n", buffer.toString());
}
}</source>



<pre class=codeResult>buffer after inserts:
33.3 2.5 10000000 7 K true def abcdef goodbye hello
buffer after deletes:
332.5 10000000 7 K true def abcdef goodbye hello</pre>

== The append() method returns a reference to the extended StringBuffer object ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer newString = new StringBuffer("abcde1234567890");

StringBuffer newBuffer = newString.append("saves nine");

System.out.println(newBuffer);

}
}</source>



<pre class=codeResult>abcde1234567890saves nine</pre>

== The ensureCapacity() method changes the default capacity of a StringBuffer object ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer newString = new StringBuffer("abcde");

System.out.println(newString.capacity());

newString.ensureCapacity(40);

System.out.println(newString.capacity());
}
}</source>



<pre class=codeResult>/*
21
44</pre>

== The Length of a StringBuffer Object ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer aString = new StringBuffer("ABCDE");
int length = aString.length();
System.out.println(length);
}
}</source>



<pre class=codeResult>5</pre>

== To find out a StringBuffer object"s capacity ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer newString = new StringBuffer("abcde");

System.out.println(newString.capacity());
}
}</source>



<pre class=codeResult>21</pre>

== Using the deleteCharAt() method to remove a character from a StringBuffer object at the index position ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer phrase = new StringBuffer("one two three four");
phrase.deleteCharAt(10);
System.out.println(phrase);
}
}</source>



<pre class=codeResult>one two thee four</pre>

== You can also create a StringBuffer object using a reference stored inariable of type String: ==



<source lang="java">
public class MainClass {
public static void main(String[] arg) {
StringBuffer aString = new StringBuffer("ABCDE");

String phrase = "abced";
StringBuffer buffer = new StringBuffer(phrase);
System.out.println(aString);
System.out.println(buffer);
}
}</source>



<pre class=codeResult>ABCDE
abced</pre>

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Admin: 1 версия