equals与==

equals ：忽略引用，判断对象的值是否相等；
==      ：若比较常量池中的变量，判断的是值是否相等；若比较的是其它，判断的是对象的引用是否相等。
eg：

public class TestEquals {

public static void main(String[] args) {

String a = "hello";

String b = "hello";

String c = new String("hello");

if(a==b){

System.out.println("a == b");

}else{

System.out.println("a != b");

}

if(a==c){

System.out.println("a == c");

}else{

System.out.println("a != c");

}

if(a.equals(c)){

System.out.println("a equals c");

}else{

System.out.println("a not equals c");

}

c=c.intern();

if(a==c){

System.out.println("a == c");

}else{

System.out.println("a != c");

}

if(a.equals(c)){

System.out.println("a equals c");

}else{

System.out.println("a not equals c");

}

/*

* 结果:

* a == b

* a != c

* a equals c

* a == c

* a equals c

*/

}

}