String s ;

String s = new String();

String s = “my name is ajun”；

String s = new String("my name is ajun");

package com.ajun.test.innerclass.example; 
 
/** 
 * 水果内容 
 * @author Administrator 
 * 
 */ 
public interface Contents { 
   String value(); 
} 

package com.ajun.test.innerclass.example; 
 
/** 
 * 水果目的地 
 * @author Administrator 
 * 
 */ 
public interface Destination { 
 
  //目的地 
  String readLabel(); 
} 

package com.ajun.test.innerclass.example; 
 
public class Goods { 
 
  private String des="is ruit!!"; 
   
  //方法外部 
  private class Content implements Contents{ 
    private String name = "apple "+des; 
    @Override 
    public String value() { 
      return name; 
    } 
  } 
   
  //方法外部 
  private class GDestination implements Destination{ 
    private String label ; 
    private GDestination(String label){ 
      this.label= label; 
    } 
    @Override 
    public String readLabel() { 
      return label; 
    } 
  } 
   
   
  //匿名内部类 
  public Destination getdestination(final String label){ 
    return new Destination(){ 
      @Override 
      public String readLabel() { 
        return label; 
      } 
    }; 
  } 
   
  public Destination dest(String s){ 
    return new GDestination(s); 
  } 
   
  public Contents content(){ 
    return new Content(); 
  } 
   
  public Destination dest2(String s){ 
    class GDestination implements Destination{ 
        private String label; 
        private GDestination(String label){ 
          this.label= label; 
        } 
        @Override 
        public String readLabel() { 
          return label; 
        } 
    } 
    return new GDestination(s); 
  } 
   
} 

package com.ajun.test.innerclass.example; 
 
public class Test { 
 
  public static void main(String [] a){ 
    Goods gs = new Goods(); 
    Contents c = gs.content(); 
    Destination d = gs.dest("Beijing"); 
    System.out.println(c.value()); 
    System.out.println(d.readLabel()); 
    Destination d1 = gs.getdestination("Shanghai"); 
    System.out.println(d1.readLabel()); 
    System.out.println(gs.dest2("Tianjin").readLabel()); 
  } 
} 

apple is ruit!! 
Beijing 
Shanghai 
Tianjin