Java日誌第12天 2020.7.17

阿新 • • 發佈：2020-07-17

第五章類的繼承和多型

5.6綜合例項

一般試卷中都有選擇題，選擇題又可分為單選擇題和多選擇題。其簡單的流程圖如圖5-4所示。

父類Question定義：

子類SingleQuestion

子類MultiQuestion

測試類PaperDemo

5.8 上機練習

1.請分別定義父類People和子類Student，觀察Student是如何共享父類屬性和方法的。

public class People {
    public String name;
    public String sex;
    public int age;
    public String getName(){
 
        return name;
    }
    public void setName(String name){
        this.name=name;
    }
    public String getSex(){
        return sex;
    }
    public void setSex(String sex){
        this.sex=sex;
    }
    public int getAge(){
        return age;
    }
    public void setAge(int age){
        this.age=age;
 
    }
}

public class Student extends People {
    private String deparetment;//系別
    private String specialty;//專業
    String name = super.name;
    public void test(){
        super.getAge();
    }
}

2.在題1的People中定義final方法，然後在類Student中定義與該final相同的方法，觀察Student的變化。

public class People {
    public String name;
    public String sex;
 
    public int age;
    public String getName(){
        return name;
    }
    public void setName(String name){
        this.name=name;
    }
    public String getSex(){
        return sex;
    }
    public void setSex(String sex){
        this.sex=sex;
    }
    public int getAge(){
        return age;
    }
    public void setAge(int age){
        this.age=age;
    }
    public final void test1(){
    }
    private final void test2(){
    }
}

public class Student extends People {
    private String deparetment;//系別
    private String specialty;//專業
    String name = super.name;
    public void test(){
        super.getAge();
    }
    public void test1(){//父類許可權為public，且被final修飾報錯！
    }
    public void test2(){//父類許可權為private，且被final修飾 不報錯！
    }
}

3.將題目1的父類People定義成抽象類，用子類Student來繼承它。

public abstract class People {
    public String name;
    public String sex;
    public int age;
    public String getName(){
        return name;
    }
    public void setName(String name){
        this.name=name;
    }
    public String getSex(){
        return sex;
    }
    public void setSex(String sex){
        this.sex=sex;
    }
    public int getAge(){
        return age;
    }
    public void setAge(int age){
        this.age=age;
    }
    public abstract void setValues(String name,String sex,int age);
}



public class Student extends People {
    private String deparetment;//系別
    private String specialty;//專業
    String name = super.name;
    public void test(){
        super.getAge();
    }
    public void setValues(String name,String sex,int age){
        super.name=name;
        this.sex=sex;
        this.age=age;
    }

    public static void main(String[] args) {
        People people = new Student();
        people.setValues("伍正雲","男",25);
        System.out.print(people.getName()+"\t"+people.getSex()+"\t"+people.getAge());
        System.out.println();
    }
}