编写一个java程序,其中包含至少一个抽象类以及一个接口,再定义一个类实现抽象类以及接口中的方法

接口
package com.cmb.reqmgr;

public interface HelloInterface {
public void sayHello();
}

接口实现
package com.cmb.reqmgr;

public class HellpImpl implements HelloInterface {

public void sayHello() {
System.out.println("hello");
}

}

抽象类
package com.cmb.reqmgr;

public abstract class HelloAbstrator {
public void sayHello(){
System.out.println("hello");
}
public abstract void sayHello(String name);
}

抽象类实现
package com.cmb.reqmgr;

public class HelloAbstratorImpl extends HelloAbstrator {

@Override
public void sayHello(String name) {
System.out.println("hello" + name);
}

}本回答被网友采纳

//定义接口
public interface Jiekou {
double pi=3.14;
double surface();
double volume();
}
//实现接口
public class Ball implements Jiekou{
double radius;
public Ball (double r){
radius=r;
}
public double surface(){
return (4 * pi * radius * radius );
}
public double volume(){
return (4 * 1/3 *pi * radius * radius * radius);
}
}
//测试类
public class Test {

public static void main(String[] args) {

Ball ball1 = new Ball(10);
System.out.println("surface="+ball1.surface());
System.out.println("volum="+ball1.volume());

}

}