"this"的含义是什么?在Java中? [英] What is the meaning of "this" in Java?

问题描述

通常，我仅在构造函数中使用this.

Normally, I use this in constructors only.

我了解，如果它与全局变量具有相同的名称，则它用于标识参数变量(通过使用this.something).

I understand that it is used to identify the parameter variable (by using this.something), if it have a same name with a global variable.

但是，我不知道this的真正含义在Java中是什么，如果我使用不带点(.)的this会发生什么.

However, I don't know that what the real meaning of this is in Java and what will happen if I use this without dot (.).

推荐答案

this引用当前对象.

每个非静态方法都在对象的上下文中运行.因此，如果您有这样的课程:

Each non-static method runs in the context of an object. So if you have a class like this:

public class MyThisTest {
  private int a;

  public MyThisTest() {
    this(42); // calls the other constructor
  }

  public MyThisTest(int a) {
    this.a = a; // assigns the value of the parameter a to the field of the same name
  }

  public void frobnicate() {
    int a = 1;

    System.out.println(a); // refers to the local variable a
    System.out.println(this.a); // refers to the field a
    System.out.println(this); // refers to this entire object
  }

  public String toString() {
    return "MyThisTest a=" + a; // refers to the field a
  }
}

然后在new MyThisTest()上调用frobnicate()将会打印

1
42
MyThisTest a=42

因此，有效地将它用于多种用途:

So effectively you use it for multiple things:

• 在还有其他与该字段同名的东西时，澄清您在谈论一个字段
• 整体引用当前对象
• 在构造函数中调用当前类的其他构造函数

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