什么时候在 Java 类中使用关键字 ‘this’ ？

this 是 Java 中的一个关键字，用于在实例方法或构造函数中引用当前类的对象。使用 this 可以引用类的成员，例如构造函数、变量和方法。

示例

实时演示

public class This_Example {
   // Instance variable num
   int num = 10;
   
   This_Example() {
      System.out.println("This is an example program on keyword this");
   }
   This_Example(int num) {
   
      // Invoking the default constructor
      this();
      
      // Assigning the local variable num to the instance variable num
      this.num = num;
   }
   public void greet() {
      System.out.println("Hi Welcome to Tutorialspoint");
   }
   public void print() {
      // Local variable num
      int num = 20;
      
      // Printing the local variable
      System.out.println("value of local variable num is : "+num);
      
      // Printing the instance variable
      System.out.println("value of instance variable num is : "+this.num);
      
      // Invoking the greet method of a class
      this.greet();
   }
   public static void main(String[] args) {
      // Instantiating the class
      This_Example obj1 = new This_Example();
      
      // Invoking the print method
      obj1.print();
      
      // Passing a new value to the num variable through parametrized constructor
      This_Example obj2 = new This_Example(30);
      
      // Invoking the print method again
      obj2.print();
   }
}

输出

This is an example program on keyword this
value of local variable num is : 20
value of instance variable num is : 10
Hi Welcome to Tutorialspoint
This is an example program on keyword this
value of local variable num is : 20
value of instance variable num is : 30
Hi Welcome to Tutorialspoint

更新日期：30-07-2019

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