求Java程序。。。（2）设计一个People接口，其中有eat( )、sleep（）、run（）、study（）等方法

2）
public interface People{
public void eat();
public void sleep();
public void run();
public void study();
}
class Man implements People{
public void eat(){
System.out.println("Man eat !");
}
public void sleep(){
System.out.println("Man sleep !");
}
public void run(){
System.out.println("Man run !");
}
public void study(){
System.out.println("Man study !");
}
}
class Woman implements People{
public void eat(){
System.out.println("Woman eat !");
}
public void sleep(){
System.out.println("Woman sleep !");
}
public void run(){
System.out.println("Woman run !");
}
public void study(){
System.out.println("Woman study !");
}
}
class Child implements People{
public void eat(){
System.out.println("Child eat !");
}
public void sleep(){
System.out.println("Child sleep !");
}
public void run(){
System.out.println("Child run !");
}
public void study(){
System.out.println("Child study !");
}
}
3）

public abstract class People { public abstract void eat();
public abstract void sleep();
public abstract void run();
public abstract void study();
}
class Man extends People{
public void eat(){
System.out.println("Man eat !");
}
public void sleep(){
System.out.println("Man sleep !");
}
public void run(){
System.out.println("Man run !");
}
public void study(){
System.out.println("Man study !");
}
}
class Woman extends People{
public void eat(){
System.out.println("Woman eat !");
}
public void sleep(){
System.out.println("Woman sleep !");
}
public void run(){
System.out.println("Woman run !");
}
public void study(){
System.out.println("Woman study !");
}
}
class Child extends People{
public void eat(){
System.out.println("Child eat !");
}
public void sleep(){
System.out.println("Child sleep !");
}
public void run(){
System.out.println("Child run !");
}
public void study(){
System.out.println("Child study !");
}
}
4)
建议用接口，java单继承的特性决定了美人鱼不能既继承人的特性，又有鱼的特点；借口弥补了这一不足，通过借口可以定义行为，不需要担心具体怎么去做，java类可以实现多个借口来实现各种动作