package lxg;
public class main {

public static void main(String[] args) {
 String name = "lengxuegang";
 String nickname = "lengxuegang";
 String signature = "leng" + "xue" + "gang";
 System.out.println(name == nickname);
 System.out.println(name == signature);
}
}

true
true

package lxg;
public class main {
public static void main(String[] args) {
 String name = "lengxuegang";
 String nickname = new String("lengxuegang");
 System.out.println(name == nickname);

 //调用intern方法后，nickname指向常量池中"lengxuegang"的引用，此时name与nickname相同 
 nickname = nickname.intern(); 
 System.out.println(name == nickname);
}
}

false
true