String類的構造方法：

1)String()

2)String(byte[])

3)String(byte[],int,int)

4)String(byte[],int,int,String)

5)String(byte[],String)

6)String(char[])

7)String(char[],int,int)

8)String(String)

9)String(StringBuffer)

10)String(String)

基本操作1：取字串charAt(int index)

package com.study;
public class Test {
	public static void testString(){
		<strong>String str=new String("Hello world");
		char c=str.charAt(0); //取字串操作</strong>
		System.out.print(c);
	}		
	public static void main(String[] args) {
		Test.testString();
	}
}
 

輸出:H

基本操作2：比較字串compareTo(Object o)、compareTo(String str)、CompareToIgnore(String str)

package com.study;
public class Test {
	public static void testString(){ <strong>//compareTo()和CompareToIgnore()返回值為0，則表示相同</strong>
		String str=new String("Hello world");
		String str2 ="Hello world";
		<strong>System.out.println("compareTo:"+(str.compareTo(str2)==0));
		System.out.println("compareToIgnoreCase:"+(str.compareToIgnoreCase(str2)==0));</strong>
	}	
	public static void main(String[] args) {
		Test.testString();<pre name="code" class="java">String s="you are a little boy!";
char[] c=new char[s.length()];
c=s.toCharArray();
System.out.print(c);
 

}} 輸出結果：

compareTo:truecompareToIgnoreCase:true

基本操作3：連線字串concat(String str)

String str=new String("01234");
String str2 ="5678";
System.out.println(str.concat(str2));	

輸出結果：012345678

基本操作4：字元陣列轉為字串  copyValueOf(char[] data) 、 copyValueOf(char[] data,int offset,int count) ,String(char[] data)、String(char[] ,int,int)

char data[]={'a','b','c','d'};
String str=String.copyValueOf(data);		
System.out.println(str);

輸出結果：abcd

這樣也行：

char data[]={'a','b','c','d'};
String str=new String(data);		
System.out.println(str);

輸出結果：abcd

還有這樣：

char data[]={'a','b','c','.'};
String str=String.copyValueOf(data,1,2);		
System.out.println(str);	

輸出結果：bc

還有啊:

char data[]={'a','b','c','.'};
String str=new String(data,1,2);		
System.out.println(str);

輸出結果：bc

基本操作5：字串轉為字元陣列getChars(int beigin,int end,char[] data,int dstBegin)、toCharArray

String s="you are a little boy!";
char[] c=new char[s.length()];
s.getChars(0, s.length(), c, 0);
System.out.print(c);

輸出結果：you are a little boy!

String s="you are a little boy!";
char[] c=new char[s.length()];
c=s.toCharArray();
System.out.print(c);

輸出結果：you are a little boy!

基本操作6：判斷字串結束內容endsWith(String s)

                  同理：判斷起始子串startsWith(String s),startsWith(String s,int toffset)

String s="you are a little boy!";
boolean b=s.endsWith("boy!");
System.out.print(b);

輸出結果：true

基本操作7：字串物件是否相等equals(Object o)、equalsIgnoreCase(String s)

String s="you are a little boy!";
boolean b1=s.equals("boy!");
boolean b2=s.equals("you are a little boy!");
boolean b3=s.equalsIgnoreCase("you are a little boy!");
System.out.print(b1+","+b2+","+b3);

輸出結果：false,true,true

基本操作8：字串中的字元的定位indexOf(int ch)、indexOf(int ch,int fromindex)、indexof(String s),indexOf(String s,int fromindex)

String s="you are a little boy!";
int pos =s.indexOf('a');
int pos1=s.indexOf("are");
int pos2=s.indexOf('y',2);
System.out.print(pos+"和"+pos1+"and"+pos2);

輸出結果：4和4and19

基本操作9：字串中的字元最後的位置lastIndexOf(int ch),lastIndexOf(int ch,int fromindex),lastIndexOf(String s),lastIndexOf(String s,int fromindex)

String s="you are a little boy!";
int pos =s.lastIndexOf('a');
int pos1=s.lastIndexOf("are");
int pos2=s.lastIndexOf('y',2);
System.out.print(pos+"和"+pos1+"and"+pos2);

輸出結果：8和4and0

基本操作10：判斷長度length()

 int Len=(new Stirng("abc")).length();

基本操作11：字串內容的替換replace()

String s="you are a little boy!";
s.replace('b', 'B');
System.out.println(s);
System.out.println(s.replace('b', 'B'));

輸出結果：
you are a little boy!
you are a little Boy!

基本操作12：取子字串subString(int begin),subString(int begin,int end)

String s="you are a little boy!";	
System.out.println(s.substring(0));
System.out.println(s.substring(0,5));

輸出結果：

you are a little boy!
you a

基本操作13：字串大小寫轉換toUpperCase().toLowerCase()

String s="you are a little boy!";	
System.out.println(s.toUpperCase());
System.out.println(s.toLowerCase());

輸出結果：

YOU ARE A LITTLE BOY!
you are a little boy!

基本操作14:將其他型別轉為String：valueOf()

int n=5;
char[] c={'a','b'};
String s1,s2;	
s1=String.valueOf(n);
s2=String.valueOf(c);
System.out.print(s1+"和"+s2);

輸出結果：5和ab