第六章類(Class) 和物件(Object)-有解無憂

一、筆記導圖

二、實體代碼：

public class PrintCarStatus{
    public static void main(String[] args){
        int speed;   
        String color; 
        String name; 
        String direction; 
        speed = 200;      
        color = "紅色";
        name = "法拉利";
        direction = "紐博格林南環賽道";
        System.out.println("經過的汽車的速度為："+ speed);
        System.out.println("它的顏色是："+ color);
        System.out.println("汽車的名字叫做"+ name);
        System.out.println("汽車的行駛方向為"+ direction);
    }
}

//創建一個Car類，或定義Car類
public class Car{
    int speed;
    String name;
    String color;
    String direction;
}

public class UseCar {
    public static void main(String[] args) {
        Car carPassedBy;          //1）宣告一個Car類的變數
        carPassedBy = new Car();  //2）創建一個Car類的物體
        carPassedBy.speed = 60;   //3）通過carPassedBy給Car物體的各個屬性賦值
        carPassedBy.color = "紅色";
        carPassedBy.name = "法拉利";
        carPassedBy.direction = "紐博格林南環賽道";
        System.out.println("經過的汽車的速度為："+ carPassedBy.speed); //4）通過carPassedBy輸出Car物體的各個屬性的值
        System.out.println("它的顏色是："+ carPassedBy.color);
        System.out.println("汽車的名字叫做："+ carPassedBy.name);
        System.out.println("汽車的行駛方向為："+ carPassedBy.direction);
    }
}

public class Plural{
    int realPart;    //保存復數實部的值
    int virtualPart; //保存復數虛部的值
}

public class UsePlural{
    public static void main(String[] args){
        Plural a;            //宣告一個復數a
        a = new Plural();    //創建一個復數物件
        a.realPart = 5;      //給這個復數物件的realPart屬性賦值
        a.virtualPart = 10;  //給這個復數物件的virtualPart屬性賦值
        System.out.println("復數的實部為"+ a.realPart); 
        System.out.println("復數的虛部為"+ a.virtualPart); 
    }
}

public class Driver{
    String name;  //默認值為null
    int age;  //默認預設值為0
    Car car;  //默認值為null
}

public class PrintDriverProps{
    public static void main(String[] agrs){
        Driver driver = new Driver();
        /*System.out.println(driver.name); 
        System.out.println(driver.age); 
        System.out.println(driver.car); */
        System.out.println(driver.age);
        if (driver.name !=null){
            System.out.println("司機的名字為：" + driver.name);
        }else {
            System.out.println("沒司機的名字");
        }
        if (driver.car !=null){
            System.out.println("司機的資訊為：" + driver.car);
        }else {
            System.out.println("沒司機的資訊");
        }
    }
}

三、練習題

public class UseBook{
    public static void main(String[] args){
        Book book = new Book();
        book.bookName = "java從入門到放棄";
        book.pageCount = 641;
        book.price = 74.5;
        System.out.println("這本書的書名為：" + book.bookName );
        System.out.println("這本書頁數共有：" + book.pageCount );
        System.out.println("這本書的價格是：" + book.price );
    }
}

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第六章 類(Class) 和物件(Object)

第六章類(Class) 和物件(Object)