Java中的this、super、final关键字详解

class Person{ // 定义Person类
		private String name ;
		private int age ;
	public Person(String name,int age){
		this.name = name ;
		this.age = age ; }
	public void getInfo(){
		System.out.println("姓名：" + name) ;
		this.speak();
	}
	public void speak(){
		System.out.println(“年龄：” + this.age);
	}
}

class Person{ // 定义Person类
		String name;
	Person(String name){
		this.name = name;
		}
	public void getInfo(){
		System.out.println("Person类 --> " + this.name);
		}
	public boolean compare(Person p){
		return this.name==p.name;
	}
}
	public class PersonTest{
	public static void main(String args[]){
		Person per1 = new Person("张三") ;
		Person per2 = new Person("李四") ;
		per1.getInfo() ; // 当前调用getInfo()方法的对象是per1
		per2.getInfo() ; // 当前调用getInfo()方法的对象是per2
		boolean b = per1.compare(per2);
	} 
}

class Person{ // 定义Person类
		private String name ;
		private int age ;
		public Person(){ // 无参构造器
		System.out.println("新对象实例化") ;
}
	public Person(String name){
		this(); // 调用本类中的无参构造器
		this.name = name ;
}
	public Person(String name,int age){
		this(name) ; // 调用有一个参数的构造器
		this.age = age;
}
	public String getInfo(){
		return "姓名：" + name + "，年龄：" + age ;
	}
}

class protected Person {
		String name = "张三"; 
		protected int age;
	public String getInfo() {
		return "Name: " + name + "\nage: " + age;
	}
}
class Student extends Person {
		protected String name = "李四";
		private String school = "New Oriental";
	public String getSchool() {
		return school;
	}
	public String getInfo() {
		return super.getInfo() + "\nschool: " + school;
	}
}
	public class StudentTest {
	public static void main(String[] args) {
		Student st = new Student();
	System.out.println(st.getInfo());
	}
}

public class Person {
		private String name;
		private int age;
		private Date birthDate;
	public Person(String name, int age, Date d) {
		this.name = name;
		this.age = age;
		this.birthDate = d;
	}
	public Person(String name, int age) {
		this(name, age, null);
	}
	public Person(String name, Date d) {
		this(name, 30, d);
	}
	public Person(String name) {
		this(name, 30);
	}
}
public class Student extends Person {
		private String school;
	public Student(String name, int age, String s) {
		super(name, age);
		school = s;
	}
	public Student(String name, String s) {
		super(name);
		school = s;
	}
	// 编译出错: no super(),系统将调用父类无参数的构造器。
	public Student(String s) {
		school = s;
	}
}

public final class Test {
		public static int totalNumber = 5;
		public final int ID;
	public Test() {
		ID = ++totalNumber; // 可在构造器中给final修饰的“变量”赋值
	}
	public static void main(String[] args) {
		Test t = new Test();
		System.out.println(t.ID);
		final int I = 10;
		final int J;
		J = 20;
		J = 30; // 非法
	}
}