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How to use this method in Java

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Release： 2023-04-18 13:58:03

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1. this keyword

1. The type of this: Which object is called is the reference type of that object

How to use this method in Java

2. Usage summary

1.this.data; //Access properties

2.this.func(); //Access method

3.this(); //Call other constructors in this class

3. Explanation of usage

1.this.data

This is used in member methods

Let's take a look at what will happen if this is not added

class MyDate{
    public int year;
    public int month;
    public int day;
 
    public void setDate(int year, int month,int day){
        year = year;//这里没有加this
        month = month;//这里没有加this
        day = day;//这里没有加this
    }
    public void PrintDate(){
        System.out.println(year+"年 "+month+"月 "+day+"日 ");
    }
}
public class TestDemo {
    public static void main(String[] args) {
        MyDate myDate = new MyDate();
        myDate.setDate(2000,9,25);
        myDate.PrintDate();
        MyDate myDate1 = new MyDate();
        myDate1.setDate(2002,7,14);
        myDate1.PrintDate();
    }
}

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The expectation we want to achieve is to output September 25, 2000, and July 14, 2002 respectively.

And the actual output result is

How to use this method in Java

And when we add this

class MyDate{
    public int year;
    public int month;
    public int day;
 
    public void setDate(int year, int month,int day){
       this.year = year;
       this.month = month;
       this.day = day;
    }
    public void PrintDate(){
        System.out.println(this.year+"年 "+this.month+"月 "+this.day+"日 ");
    }
}
public class TestDemo {
    public static void main(String[] args) {
        MyDate myDate = new MyDate();
        myDate.setDate(2000,9,25);
        myDate.PrintDate();
        MyDate myDate1 = new MyDate();
        myDate1.setDate(2002,7,14);
        myDate1.PrintDate();
    }
}

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How to use this method in Java

realizes the function of assignment. In order to avoid errors, we recommend bringing this

2.this.func()

One refers to using this in a normal member method to call another member method

class Student{
    public String name;
    public void doClass(){
        System.out.println(name+"上课");
        this.doHomeWork();
    }
    public void doHomeWork(){
        System.out.println(name+"正在写作业");
    }
}
public class TestDemo2 {
    public static void main(String[] args) {
        Student student = new Student();
        student.name = "小明";
        student.doClass();
    }
}

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Running result:

How to use this method in Java

(3)this()

This refers to using this in the constructor method to call other constructors of this class

When using this, please pay attention to the following points

1. this can only call other constructors in the constructor

2.this must be placed in the first line

3.Only one constructor can be called in one constructor

How to use this method in Java

operation result

How to use this method in Java

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