字符串相等equals与==

　　

public class Test_String_equals {

    public static void main(String[] args) {
        String a1 = new String("hello world!");
        String a2 = new String("hello world!");

        System.out.println("a1==a2:"+a1==a2);false
        System.out.println("a1.equals(a2): "+a1.equals(a2)); //true
    }

}