Java String intern方法

public class Example{  
   public static void main(String args[]){  
    String str1 = "beginnersbook";    

    /* The Java String intern() method searches the string "beginnersbook"  
     * in the memory pool and returns the reference of it.
     */
    String str2 = new String("beginnersbook").intern(); 
    //prints true 
    System.out.println("str1==str2: "+(str1==str2));
   }
}

str1==str2: true

public class Example{  
   public static void main(String args[]){  
    String str1 = "Hello";

    //Java automatically interns this   
    String str2 = "Hello";

    //This is same as creating string using string literal      
    String str3 = "Hello".intern();

    //This will create a new instance of "Hello" in memory
    String str4 = new String("Hello");

    if ( str1 == str2 ){
        System.out.println("String str1 and str2 are same");
    }

    if ( str2 == str3 ){
        System.out.println("String str2 and str3 are same" );
    }

    if ( str1 == str4 ){
        //This will not be printed as the condition is not true
        System.out.println("String str1 and str4 are same" );  
    }

    if ( str3 == str5 ){
        System.out.println("String str3 and str5 are same" );  
    }
   }
}

String str1 and str2 are same
String str2 and str3 are same
String str3 and str5 are same