1 package com_package2; 2 3 public class Person3 { 4 private int age; 5 private String name; 6 public int getAge() { 7 return age; 8 } 9 public void setAge(int age) { 10 this.age = age; 11 } 12 public String getName() { 13 return name; 14 } 15 public void setName(String name) { 16 this.name = name; 17 } 18 Person3() 19 { 20 System.out.println("hahahaa"); 21 22 } 23 Person3(String n,int a) 24 { 25 name = n; 26 age = a; 27 28 } 29 Person3(String n) 30 { 31 name = n; 32 33 } 34 Person3(int a) 35 { 36 37 age = a; 38 } 39 public void speak() 40 { 41 System.out.println("name = "+name+" "+"age="+age); 42 43 } 44 }
1 package com_package2; 2 3 public class Person3Demo { 4 public static void main(String[]args) 5 { 6 Person3 p = new Person3(); 7 p.speak(); 8 Person3 p1 = new Person3("hejinjin",23); 9 p1.speak(); 10 Person3 p2 = new Person3("hejinjin"); 11 p2.speak(); 12 Person3 p3 = new Person3(23); 13 p3.speak(); 14 show(); 15 16 } 17 public static void show() 18 { 19 System.out.println("haha"); 20 21 } 22 23 }
hahahaa
name = null age=0
name = hejinjin age=23
name = hejinjin age=0
name = null age=23
haha
改成this关键字后：
package com_package2; public class Person3 { private int age; private String name; public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } Person3() { System.out.println("hahahaa"); } Person3(String name,int age) { this.name = name; this.age = age; } Person3(String name) { this.name = name; } Person3(int age) { this.age = age; } public void speak() { System.out.println("name = "+this.name+" "+"age="+this.age); } }
注意this关键字的格式：this.类中的属性 = 参数中含有的变量
当成员变量和局部变量同名的时候，为了区分，可以使用一个关键字来完成。关键字：this
this：代表的是一个对象，哪个对象调用this所在的函数，this就代表哪个对象，this就是当前对象的一个引用
this什么用：当定义功能的时候，功能内部使用到了调用该功能的对象，这是就用this来表示
this的表现形式一：当局部变量和成员变量同名的时候，可以用this来区分
this的表现形式二：构造函数之间的调用可以使用this关键字，后面跟上小括号，指定其具体的实参即可明确要调用的构造函数
用this关键字进行一般函数调用一般函数：
package com_package2; public class Person3 { private int age; private String name; public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } Person3() { System.out.println("hahahaa"); } Person3(String name,int age) { this(name); this.name = name; this.age = age; } Person3(String n) { this.name = name; } Person3(int age) { this.age = age; } public void speak() { System.out.println("name = "+this.name+" "+"age="+this.age); } public void show() { this.speak(); } }
package com_package2; public class Person3Demo { public static void main(String[]args) { Person3 p = new Person3(); p.speak(); Person3 p1 = new Person3("hejinjin",23); p1.speak(); Person3 p2 = new Person3("hejinjin"); p2.speak(); Person3 p3 = new Person3(23); p3.speak(); p1.show(); } }
利用this关键字进行构造函数和构造函数之间的调用：
package com_package2; public class Person3 { private int age; private String name; public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } Person3() { System.out.println("hahahaa"); } Person3(String name,int age) { // this(); this.name = name; this.age = age; } Person3(String name) { //this(); this.name = name; } Person3(int age) { this("hejinjin",342); this.age = age; } public void speak() { System.out.println("name = "+this.name+" "+"age="+this.age); } public void show() { this.speak(); } }
package com_package2; public class Person3Demo { public static void main(String[]args) { Person3 p = new Person3(); p.speak(); Person3 p1 = new Person3("hejinjin",23); p1.speak(); Person3 p2 = new Person3("hejinjin"); p2.speak(); Person3 p3 = new Person3(238); p3.speak(); p1.show(); } }
hahahaa
name = null age=0
name = hejinjin age=23
name = hejinjin age=0
name = hejinjin age=238
name = hejinjin age=23
特殊情况：注意：调用本类中的构造函数的this语句必须定义在构造函数的第一行，因为初始化动作要先完成