Java中的抽象类与abstract 关键字使用详解

public sbatract class Shape{ }

public abstract void draw();

public abstract class Shape {
    public String name;
    public void create(){
    }
    public abstract void draw();
}

public class Cycle extends Shape{
    @Override
    public void draw() {
        System.out.println("画一个圆形。");
    }
}

public class Flower extends Shape{
    @Override
    public void draw() {
        System.out.println("画一朵花。");
    }
}

public class Test {
    public static void main(String[] args) {
        Cycle cycle = new Cycle();
        Flower flower = new Flower();
        Shape[] shapes = {cycle,flower,cycle,flower};
        for (Shape s : shapes){
            s.draw();
        }
    }
}

public class Test {
    public static void main(String[] args) {
        //Shape shape = new Shape(); // 不行
        Shape shape = new Cycle(); // 可以，向上转型
    }
}

public abstract class Shape {
    public abstract void draw();
}
abstract class SolidShape extends Shape{ // 立体图形
    abstract void test();
}
class Cylinder extends SolidShape{  // 柱体
    @Override
    void test() {
    }
    @Override
    public void draw() {
    }
}

public class Test {
    public static void drawMap(Shape shape){
        shape.draw();
    }
    public static void main(String[] args) {
        drawMap(new Cycle()); // 传的参数是匿名对象
        drawMap(new Flower());
    }
}

public class Test {
    public static void drawMap(Shape shape){
        shape.draw();
    }
    public static void main(String[] args) {
        Cycle cycle = new Cycle();
        drawMap(cycle);
        drawMap(cycle); // 只用实例化一个对象，传的是同一个对象
        cycle.draw();
        cycle.draw();
        // ======采用匿名对象======
        drawMap(new Cycle()); // 传的参数是匿名对象
        drawMap(new Cycle()); // 实例化了两个对象
        new Cycle().draw();
        new Cycle().draw();
    }
}