String 深浅拷贝的测试---有待继续测试

public class TestString {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String str = new String();
        str = "12345";
        
        String str_1 = str;
        
        String str_2 = null;
        str_2 = str;
        
        String str_3 = new String();
        str_3 = str;
        
        System.out.println("str:"+str);
        System.out.println("str_1:"+str_1);
        System.out.println("str_2:"+str_2);
        System.out.println("str_3:"+str_3);
        
        
        str = "2345678";
        
        System.out.println("str:"+str);
        System.out.println("str_1:"+str_1);
        System.out.println("str_2:"+str_2);
        System.out.println("str_3:"+str_3);
    }

}