java創建抽象類

⑴ 編寫一個完整的 java 程序，要求: (1)定義一個抽象類 Shape，在該類中:添加抽象方法

public abstract class Shape {
public abstract double Area();
public abstract void printArea();
}

class Circle extends Shape {
int radius;

public Circle(int radius) {
this.radius = radius;
}

@Override
public double Area() {
return Math.pow(this.radius, 2) * Math.PI;
}

@Override
public void printArea() {
// String.format("%.2f", Area()) 保留兩位小數
System.out.println("半徑為 " + this.radius + " 的圓的面積是 " + String.format("%.2f", Area()));
}
}

class Test {
public static void main(String[] args) {
// 生成一個 1 - 9 的隨機整數
int radius = (int) (Math.random() * 9) + 1;
// 創建一個 Circle 對象實例
Circle circle = new Circle(radius);
// 調用 printArea() 方法列印面積
circle.printArea();
}
}

⑵ 浣跨敤java 瀹氫箟鎶借薄綾伙細public abstract class Person

浠ｇ爜濡備笅銆備負浜嗘樉紺烘柟渚挎墍浠ュ啓鍦ㄥ悓涓涓鏂囦歡閲岄潰浜嗐

publicclassTest{
	publicstaticvoidmain(String...args)throwsException{
		Personstu1=newStudent();
		stu1.preWork();
		stu1.work();
		stu1.reWork();
		stu1.doHomework();
		Persontea1=newTeacher();
		tea1.preWork();
		tea1.work();
		tea1.reWork();
		tea1.doHomework();
	}

}

abstractclassPerson{
	publicabstractvoidpreWork();

	publicabstractvoidwork();

	publicabstractvoidreWork();

	publicabstractvoiddoHomework();
}

classStudentextendsPerson{
	publicvoidpreWork(){
		System.out.println("棰勪範");
	}

	publicvoidwork(){
		System.out.println("涓婅");
	}

	publicvoidreWork(){
		System.out.println("澶嶄範");
	}

	publicvoiddoHomework(){
		System.out.println("鍐欎綔涓");
	}
}

classTeacherextendsPerson{
	publicvoidpreWork(){
		System.out.println("澶囪");
	}

	publicvoidwork(){
		System.out.println("涓婅");
	}

	publicvoidreWork(){
		System.out.println("杈呭");
	}

	publicvoiddoHomework(){
		System.out.println("鎵逛綔涓");
	}
}

⑶ java紼嬪簭棰橈細瀹氫箟涓涓鎶借薄綾-姘存灉,鍏朵腑鍖呮嫭getWeight()鏂規硶,緙栧啓紼嬪簭鍒嗗埆鍒涘緩鑻規灉銆

姘存灉綾

abstractpublicclassFruit{
	abstractpublicdoublegetWeight();
}

鑻規灉綾

publicclassAppleextendsFruit{
	privatedoubleweight;

	publicApple(doubleweight){
		this.weight=weight;
	}

	@Override
	publicdoublegetWeight(){
		returnweight;
	}

}

姍樺瓙綾

publicclassOrangeextendsFruit{
	privatedoubleweight;

	publicOrange(doubleweight){
		this.weight=weight;
	}

	@Override
	publicdoublegetWeight(){
		returnweight;
	}

}

妗冨瓙綾

publicclassPeachextendsFruit{
	privatedoubleweight;
	
	publicPeach(doubleweight){
		this.weight=weight;
	}

	@Override
	publicdoublegetWeight(){
		returnweight;
	}
}

涓葷被

publicclassMain{
	publicstaticvoidmain(String[]args){
		//TODOAuto-generatedmethodstub
		Fruit[]fruits={newPeach(12),newApple(2),newOrange(5)};
		for(Fruitfruit:fruits){
			System.out.println(fruit.getClass().getName()+"鐨勯噸閲忔槸"
					+fruit.getWeight());
		}
	}
}

榪愯岀粨鏋

Peach鐨勯噸閲忔槸 12.0

Apple鐨勯噸閲忔槸 2.0

Orange鐨勯噸閲忔槸 5.0

⑷ JAVA程序編寫。 定義一個抽象類shape ，用來表示一般圖形。

Java程序：

publicclassMain{	
	publicstaticvoidmain(String[]args){
		Shapes=null;
		s=newCircle(3);
		
		System.out.println("圓的面積："+s.area());
		System.out.println("圓的周長："+s.perimeter());
	}
}

/**
*形狀類：抽象類
*@authordeveloper
*@version2017.05.23
*/
abstractclassShape{
	/**
	*計算形狀的面積
	*@return形狀的面積
	*/
	abstractdoublearea();
	
	/**
	*計算形狀的周長
	*@return形狀的周長
	*/
	abstractdoubleperimeter();
}

/**
*圓類
*@authordeveloper
*@version2017.05.23
*/
classCircleextendsShape{
	/**
	*半徑
	*/
	protecteddoubleradius;
	
	/**
	*構造方法
	*@paramradius半徑
	*/
	publicCircle(doubleradius){
		this.radius=radius;
	}

	@Override
	doublearea(){
		returnMath.PI*radius*radius;
	}

	@Override
	doubleperimeter(){
		return2*Math.PI*radius;
	}
}

運行測試：

圓的面積：28.274333882308138
圓的周長：18.84955592153876