java学习之路----常用类库---StringBuffer类
2013-11-20 21:58
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1.StringBuffer类
在以前我们学过String类,它是一个不可改变的类,一旦声明,这不可改变。即使改变也是改变的String的引用地址
如果想要经常改变字符串,那就要用StringBuffer类
我们知道String类是用"+"来连接字符串的,但是在StringBuffer确实用append方法来连接的字符串
下面就是一些StringBuffer常用的方法
1.字符串的连接
public class StringBufferDemo {
public static void main(String[]
args) {
StringBuffer stringBuffer= new StringBuffer();
stringBuffer.append( "hello" );
stringBuffer.append( " world" ).append("!!!!" );
System. out .println(stringBuffer);
}
}
结果:
[align=left]hello world!!!![/align]
[align=left]
[/align]
[align=left]
[/align]
[align=left]2.在任意位置为StringBuffer添加内容[/align]
[align=left]
[/align]
[align=left] public class StringBufferDemo {[/align]
[align=left] [/align]
public static void main(String[]
args) {
[align=left] StringBuffer stringBuffer= new StringBuffer();[/align]
[align=left] stringBuffer.append( "hello" );[/align]
[align=left] stringBuffer.append( " world" ).append("!!!!" );[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] [/align]
[align=left] stringBuffer.insert(0, "like say" );//在初始位置(第一个位置)插入[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] stringBuffer.insert(stringBuffer.length(), "OK" );//在最后插入[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] }[/align]
[align=left]}[/align]
[align=left]结果:[/align]
[align=left]hello world!!!![/align]
[align=left]like sayhello world!!!![/align]
[align=left]like sayhello world!!!!OK[/align]
[align=left]
[/align]
[align=left]3.字符串的反转操作[/align]
[align=left]
[/align]
[align=left] public class StringBufferDemo {[/align]
[align=left] [/align]
public static void main(String[]
args) {
[align=left] StringBuffer stringBuffer= new StringBuffer();[/align]
[align=left] stringBuffer.append( "hello" );[/align]
stringBuffer.append( "
world");
[align=left] System. out .println(stringBuffer);[/align]
[align=left] [/align]
[align=left] String s= stringBuffer.reverse().toString(); //反转,在转为字符串[/align]
[align=left] System. out .println(s);[/align]
[align=left] }[/align]
[align=left]}[/align]
[align=left]结果:[/align]
[align=left]hello world[/align]
[align=left]dlrow olleh[/align]
[align=left]
[/align]
[align=left]
[/align]
[align=left]4.替换指定范围的内容[/align]
[align=left]
[/align]
[align=left]public class StringBufferDemo {[/align]
[align=left] [/align]
public static void main(String[]
args) {
[align=left] StringBuffer stringBuffer= new StringBuffer();[/align]
[align=left] stringBuffer.append( "hello" );[/align]
stringBuffer.append( "
world" );
[align=left] System. out .println(stringBuffer);[/align]
[align=left] stringBuffer.replace(6, 11, "like" );//替换6到11的字符串[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] }[/align]
[align=left]}[/align]
[align=left]
[/align]
[align=left]结果:[/align]
[align=left]hello world[/align]
[align=left]hello like[/align]
[align=left]
[/align]
[align=left]5.截取字符串[/align]
public class StringBufferDemo
{
[align=left] [/align]
public static void main(String []
args) {
[align=left] StringBuffer stringBuffer= new StringBuffer();[/align]
[align=left] stringBuffer.append( "hello" );[/align]
[align=left] stringBuffer.append( " world" );[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] stringBuffer.replace(6, 11, "like" );//替换6到11的字符串[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] String s= stringBuffer.substring(6,10); //截取6到10的字符串[/align]
[align=left] System. out .println(s);[/align]
[align=left] }[/align]
[align=left]}[/align]
[align=left]
[/align]
[align=left]结果:[/align]
[align=left]hello world[/align]
[align=left]hello like[/align]
[align=left]like[/align]
[align=left]
[/align]
[align=left]6.删除指定位置的字符串[/align]
[align=left]
[/align]
[align=left]public class StringBufferDemo {[/align]
[align=left] [/align]
public static void main(String[]
args) {
[align=left] StringBuffer stringBuffer= new StringBuffer();[/align]
[align=left] stringBuffer.append( "hello" );[/align]
[align=left] stringBuffer.append( " world" );[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] stringBuffer.replace(6, 11, "like" );//替换6到11的字符串[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] String s= stringBuffer.substring(6,10); //截取6到10的字符串[/align]
[align=left] System. out .println(s);[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] stringBuffer.delete(6, 10); //删除6到10的字符串[/align]
[align=left] [/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] [/align]
[align=left] }[/align]
[align=left]}[/align]
[align=left]结果:[/align]
[align=left]hello world[/align]
[align=left]hello like[/align]
[align=left]like[/align]
[align=left]hello like[/align]
[align=left]hello[/align]
[align=left]
[/align]
[align=left]7.查找指定的内容是否存在[/align]
[align=left]
[/align]
public static void main(String[]
args) {
[align=left] StringBuffer stringBuffer= new StringBuffer();[/align]
[align=left] stringBuffer.append( "hello" );[/align]
stringBuffer.append( "
world" );
[align=left] System. out.println(stringBuffer);[/align]
[align=left] stringBuffer.replace(6, 11, "like" );//替换6到11的字符串[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] String s= stringBuffer.substring(6,10); //截取6到10的字符串[/align]
[align=left] System. out .println(s);[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] stringBuffer.delete(6, 10); //删除6到10的字符串[/align]
[align=left] [/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] System. out .println(stringBuffer.indexOf("hello" ));//查找指定的字符串是否存在[/align]
[align=left] System. out .println(stringBuffer.indexOf("like" ));[/align]
[align=left] [/align]
[align=left] }[/align]
[align=left]}[/align]
[align=left]
[/align]
[align=left]结果:[/align]
[align=left]hello world[/align]
[align=left]hello like[/align]
[align=left]like[/align]
[align=left]hello like[/align]
[align=left]hello[/align]
[align=left]0[/align]
[align=left]-1[/align]
[align=left]
[/align]
[align=left]分析结果:0表示查找的字符串的起始位置是0开始的[/align]
[align=left]-1表示没有找到[/align]
[align=left]
[/align]
[align=left]
[/align]
[align=left] [/align]
在以前我们学过String类,它是一个不可改变的类,一旦声明,这不可改变。即使改变也是改变的String的引用地址
如果想要经常改变字符串,那就要用StringBuffer类
我们知道String类是用"+"来连接字符串的,但是在StringBuffer确实用append方法来连接的字符串
下面就是一些StringBuffer常用的方法
1.字符串的连接
public class StringBufferDemo {
public static void main(String[]
args) {
StringBuffer stringBuffer= new StringBuffer();
stringBuffer.append( "hello" );
stringBuffer.append( " world" ).append("!!!!" );
System. out .println(stringBuffer);
}
}
结果:
[align=left]hello world!!!![/align]
[align=left]
[/align]
[align=left]
[/align]
[align=left]2.在任意位置为StringBuffer添加内容[/align]
[align=left]
[/align]
[align=left] public class StringBufferDemo {[/align]
[align=left] [/align]
public static void main(String[]
args) {
[align=left] StringBuffer stringBuffer= new StringBuffer();[/align]
[align=left] stringBuffer.append( "hello" );[/align]
[align=left] stringBuffer.append( " world" ).append("!!!!" );[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] [/align]
[align=left] stringBuffer.insert(0, "like say" );//在初始位置(第一个位置)插入[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] stringBuffer.insert(stringBuffer.length(), "OK" );//在最后插入[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] }[/align]
[align=left]}[/align]
[align=left]结果:[/align]
[align=left]hello world!!!![/align]
[align=left]like sayhello world!!!![/align]
[align=left]like sayhello world!!!!OK[/align]
[align=left]
[/align]
[align=left]3.字符串的反转操作[/align]
[align=left]
[/align]
[align=left] public class StringBufferDemo {[/align]
[align=left] [/align]
public static void main(String[]
args) {
[align=left] StringBuffer stringBuffer= new StringBuffer();[/align]
[align=left] stringBuffer.append( "hello" );[/align]
stringBuffer.append( "
world");
[align=left] System. out .println(stringBuffer);[/align]
[align=left] [/align]
[align=left] String s= stringBuffer.reverse().toString(); //反转,在转为字符串[/align]
[align=left] System. out .println(s);[/align]
[align=left] }[/align]
[align=left]}[/align]
[align=left]结果:[/align]
[align=left]hello world[/align]
[align=left]dlrow olleh[/align]
[align=left]
[/align]
[align=left]
[/align]
[align=left]4.替换指定范围的内容[/align]
[align=left]
[/align]
[align=left]public class StringBufferDemo {[/align]
[align=left] [/align]
public static void main(String[]
args) {
[align=left] StringBuffer stringBuffer= new StringBuffer();[/align]
[align=left] stringBuffer.append( "hello" );[/align]
stringBuffer.append( "
world" );
[align=left] System. out .println(stringBuffer);[/align]
[align=left] stringBuffer.replace(6, 11, "like" );//替换6到11的字符串[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] }[/align]
[align=left]}[/align]
[align=left]
[/align]
[align=left]结果:[/align]
[align=left]hello world[/align]
[align=left]hello like[/align]
[align=left]
[/align]
[align=left]5.截取字符串[/align]
public class StringBufferDemo
{
[align=left] [/align]
public static void main(String []
args) {
[align=left] StringBuffer stringBuffer= new StringBuffer();[/align]
[align=left] stringBuffer.append( "hello" );[/align]
[align=left] stringBuffer.append( " world" );[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] stringBuffer.replace(6, 11, "like" );//替换6到11的字符串[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] String s= stringBuffer.substring(6,10); //截取6到10的字符串[/align]
[align=left] System. out .println(s);[/align]
[align=left] }[/align]
[align=left]}[/align]
[align=left]
[/align]
[align=left]结果:[/align]
[align=left]hello world[/align]
[align=left]hello like[/align]
[align=left]like[/align]
[align=left]
[/align]
[align=left]6.删除指定位置的字符串[/align]
[align=left]
[/align]
[align=left]public class StringBufferDemo {[/align]
[align=left] [/align]
public static void main(String[]
args) {
[align=left] StringBuffer stringBuffer= new StringBuffer();[/align]
[align=left] stringBuffer.append( "hello" );[/align]
[align=left] stringBuffer.append( " world" );[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] stringBuffer.replace(6, 11, "like" );//替换6到11的字符串[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] String s= stringBuffer.substring(6,10); //截取6到10的字符串[/align]
[align=left] System. out .println(s);[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] stringBuffer.delete(6, 10); //删除6到10的字符串[/align]
[align=left] [/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] [/align]
[align=left] }[/align]
[align=left]}[/align]
[align=left]结果:[/align]
[align=left]hello world[/align]
[align=left]hello like[/align]
[align=left]like[/align]
[align=left]hello like[/align]
[align=left]hello[/align]
[align=left]
[/align]
[align=left]7.查找指定的内容是否存在[/align]
[align=left]
[/align]
public static void main(String[]
args) {
[align=left] StringBuffer stringBuffer= new StringBuffer();[/align]
[align=left] stringBuffer.append( "hello" );[/align]
stringBuffer.append( "
world" );
[align=left] System. out.println(stringBuffer);[/align]
[align=left] stringBuffer.replace(6, 11, "like" );//替换6到11的字符串[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] String s= stringBuffer.substring(6,10); //截取6到10的字符串[/align]
[align=left] System. out .println(s);[/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] stringBuffer.delete(6, 10); //删除6到10的字符串[/align]
[align=left] [/align]
[align=left] System. out .println(stringBuffer);[/align]
[align=left] System. out .println(stringBuffer.indexOf("hello" ));//查找指定的字符串是否存在[/align]
[align=left] System. out .println(stringBuffer.indexOf("like" ));[/align]
[align=left] [/align]
[align=left] }[/align]
[align=left]}[/align]
[align=left]
[/align]
[align=left]结果:[/align]
[align=left]hello world[/align]
[align=left]hello like[/align]
[align=left]like[/align]
[align=left]hello like[/align]
[align=left]hello[/align]
[align=left]0[/align]
[align=left]-1[/align]
[align=left]
[/align]
[align=left]分析结果:0表示查找的字符串的起始位置是0开始的[/align]
[align=left]-1表示没有找到[/align]
[align=left]
[/align]
[align=left]
[/align]
[align=left] [/align]
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