If there are member variables and local variables with the same name, the data of the local variable is accessed by default inside the method. You can specify the data of the member variable to be accessed through the this keyword . In one constructor, you can call another constructor to initialize the object.
1. Use the this keyword in the method definition of the class to represent the reference of the object using the method
2. Use this## when it is necessary to indicate who is the object currently using the method.
#3. Sometimes this can be used to deal with the situation where the member variables and parameter variables in the method have the same name4.This can be regarded as a variable, and its value is a reference to the current objectNote:
When there are member variables and local variables with the same name, the local variables are accessed inside the method (Java adopts the "proximity principle" mechanism to access. ) If a variable is accessed in a method and the variable only exists as a member variable, the Java compiler will add the this keyword in front of the variable./*
this關(guān)鍵字調(diào)用其他的構(gòu)造函數(shù)要注意的事項(xiàng)：
1. this關(guān)鍵字調(diào)用其他的構(gòu)造函數(shù)時(shí)，this關(guān)鍵字必須要位于構(gòu)造函數(shù)中 的第一個(gè)語句。
2. this關(guān)鍵字在構(gòu)造函數(shù)中不能出現(xiàn)相互調(diào)用 的情況，因?yàn)槭且粋€(gè)死循環(huán)。
*/ class Student{ int id; //身份證 String name; //名字 //目前情況：存在同名 的成員 變量與局部變量，在方法內(nèi)部默認(rèn)是使用局部變量的。 public Student(int id,String name){ //一個(gè)函數(shù)的形式參數(shù)也是屬于局部變量。 this(name); //調(diào)用了本類的一個(gè)參數(shù)的構(gòu)造方法 //this(); //調(diào)用了本類無參的 構(gòu)造方法。 this.id = id; // this.id = id 局部變量的id給成員變量的id賦值 System.out.println("兩個(gè)參數(shù)的構(gòu)造方法被調(diào)用了...");
} public Student(){
System.out.println("無參的構(gòu)造方法被調(diào)用了...");
} public Student(String name){ this.name = name;
System.out.println("一個(gè)參數(shù)的構(gòu)造方法被調(diào)用了...");
}
}
class Demo7
{ public static void main(String[] args)
{
Student s = new Student(110,"鐵蛋");
System.out.println("編號："+ s.id +" 名字：" + s.name); /*
Student s2 = new Student("金胖子");
System.out.println("名字：" + s2.name);
*/ }
}For more java knowledge, please pay attention to java basic tutorial.
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