本文介绍了新Test()和新Test(){}之间的区别的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

这两种实例化类的新对象的方法有何不同,如下所示:

What is the difference between these two ways of instantiating new objects of a class as follows:

Test t1=new Test();
Test t2=new Test(){ };

当我尝试以下代码时,我可以看到两个对象都可以访问方法 foo(),但是t2无法访问变量x 变量x 不能待解决):

When I tried the following code, I could see that both objects could access the method foo(), but t2 cannot access the variable x (variable x cannot be resolved):

public class Test
{
    int x=0;
    public void foo(){ }

    public static void main (String args[])
    {
        Test t1=new Test();
        Test t2=new Test(){ };
        t1.x=10;
        t2.x=20;
        t1.foo();
        t2.foo();
        System.out.println(t1.x+" "t2.x);
    }
}


推荐答案

测试t2 = new Test(); 将创建Test类的对象。

Test t2=new Test(); will create the object of Test class.

但是测试t2 = new Test(){}; 将创建一个测试子类的对象(即匿名在这种情况下的内部类)。

But Test t2=new Test(){ }; will create a object of subclass of test (i.e. anonymous inner class in this case).

你可以为那里的任何方法提供实现,如

you can provide implementation for any method over there like

Test t2=new Test(){
public void foo(){ System.out.println("This is foo");}
};

这样当 foo()方法调用时从对象 t2 它将打印这是foo

so that when foo() method called from object t2 it will print This is foo.

添加

代码中的编译时错误是由于缺少连接操作符

Compile time error in your code is due to missing concatination operator

System.out.println(t1.x+" "+t2.x);
                          ###

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08-12 18:58