J2SE之面向对象_方法的重写

class Person {
    private String name;
    private int age;
    public void setName(String name){this.name=name;}
    public void setAge(int age) {this.age=age;}
    public String getName(){return name;}
    public int getAge(){return age;}
    public String getInfo() {
          return "Name: "+ name + "\n" +"age: "+ age;
  }
}

class Student extends Person {
    private String school;
    public String getSchool() {return school;}
    public void setSchool(String school)
    {this.school =school;}
    public String getInfo() {
      return  "Name: "+ getName() + "\nage: "+ getAge() 
                    + "\nschool: "+ school;
        }
}

public class TestOverWrite {
public static void main(String arg[]){
        Student student = new Student();
        Person person = new Person();
        person.setName("none");
        person.setAge(1000);
        student.setName("John");    
        student.setAge(18);
        student.setSchool("SCH");
        System.out.println(person.getInfo());
        System.out.println(student.getInfo());
    }
}

class SuperClass {
    private int n;
      
      /*
    SuperClass() {
        System.out.println("SuperClass()");
    }
    */
    
  
    SuperClass(int n) {
        System.out.println("SuperClass(" + n + ")");
        this.n = n;
    }
}

class SubClass extends SuperClass {
    private int n;
    
    SubClass(int n) {
            //super();
        System.out.println("SubClass(" + n + ")");
        this.n = n;
    }
    
    SubClass() {
            super(300);
        System.out.println("SubClass()");
    }
}

public class TestSuperSub {
    public static void main(String arg[]) {
        //SubClass sc1 = new SubClass();
        SubClass sc2 = new SubClass(400);
    }
}

public class TestToString
{
    public static void main(String[] args){
        Dog d = new Dog();
        System.out.println("d:="+d);
    }
}
class Dog
{
    public String toString(){
        return "I‘m a cool Dog!";
    }
}

public class TestEquals
{
    public static void main(String[] args){
        Cat c1 = new Cat(1,2,3);
        Cat c2 = new Cat(1,2,3);
        System.out.println(c1 == c2);
        System.out.println(c1.equals(c2));  //重写之前同上面一样
    }
}
class Cat
{
    int color;
    int height, weight;

    public Cat(int color, int height, int weight){
        this.color = color;
        this.height = height;
        this.weight = weight;
    }
   public boolean equals(Object obj){
    if(obj == null) return false;
    else{
      if(obj instanceof Cat){
         Cat c = (Cat)obj;
         if(c.color == this.color && c.height == this.height && c.weight == this.weight){
                return true;
          }
       }
     }
     return false;
   }
}