Java提供StringBuffer類實現對字串內容進行的動態修改。

StringBuffer類提供3種構造方法：

1)StringBuffer()

2)StringBuffer(int length)

3)StringBuffer(String s)

基本操作1:新增操作append()

StringBuffer sb=new StringBuffer();
sb.append("me");//string
sb.append('a');//char
sb.append(true);//boolean
sb.append(1);//int	
System.out.print(sb.toString());
 

基本操作2：插入操作insert()

StringBuffer sb=new StringBuffer();
sb.insert(0, "wo");//insert(int offset,String s)
sb.insert(0, 1);//insert(int offset,int a)
sb.insert(0, true);//insert(int offset,Boolean b)
sb.insert(0, new char[]{'a','b','c'});//insert(int offset,char[] c)		
sb.insert(0, new char[]{'a','b','c'},1,2);//insert(int offset,char[] c,int fromindex,int endindex)
System.out.print(sb.toString());
 

基本操作3：StringBuffer轉為String:toString()

StringBuffer sb=new StringBuffer();
sb.append("wo");
String s=sb.toString();		
System.out.print(s);

基本操作4：取字元charAt(int index)

StringBuffer sb=new StringBuffer();
sb.append("wo");
char s=sb.charAt(0);		
System.out.print(s);

基本操作5：刪除字元delete(int start,int end)、deleteCharAt(int index)

StringBuffer sb=new StringBuffer("I just want to try !");		
sb.delete(1,sb.length());		
System.out.print(sb.toString());

StringBuffer sb=new StringBuffer("I just want to try !");		
sb.deleteCharAt(0);		
System.out.print(sb.toString());

基本操作6：清空字串：SetLength(int newLength)=======（通過重新設定緩衝區長度）

StringBuffer sb=new StringBuffer("I just want to try !");			
sb.setLength(0);
System.out.println(sb);

基本操作7：內容替換replace(int start,int end,String str)

StringBuffer sb=new StringBuffer("I just want to try !");			
sb.replace(0, sb.length(),new String("I want to be replaced"));
System.out.println(sb.toString());

基本操作8：取子字串subString(int start,int end)、subString(int start)

StringBuffer sb=new StringBuffer("I just want to try !");			
String s=sb.substring(0,5); //sb.subString(0)
System.out.println(s);

基本操作9：字串反轉reverse()

StringBuffer sb=new StringBuffer("I just want to try !");			
sb.reverse();
System.out.println(sb.toString());

基本操作10：獲取長度length()為字串長度、capacity()為緩衝區長度

StringBuffer sb=new StringBuffer("I just want to try !");			
int len1=sb.length();
int len2=sb.capacity();
System.out.println(len1+","+len2);