本次项目是：以面向对象的思想设计动物乐园系统。 动物乐园中有猫，鸭子等成员，还可以增加新成员。 猫和鸭子都有自己的名字，都有自己的腿，但腿的条数不同，猫和鸭子会发出叫声，猫的叫声是：喵喵喵……,鸭子的

public abstract class animal {
protected String name;

public animal(String name) {
super();
this.name = name;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}
public abstract void show();

}
---------------------------------2
public interface lu {
public int leg();

}
-------------------------3

public class cat extends animal implements lu{
private int leg;

public cat(String name, int leg) {
super(name);
this.leg = leg;
}

public int getLeg() {
return leg;
}


public void setLeg(int leg) {
this.leg = leg;
}
---------------------------------------------4

public class duck extends animal implements lu {
private int leg;

public duck(String name, int leg) {
super(name);
this.leg = leg;
}

public int getLeg() {
return leg;
}

public void setLeg(int leg) {
this.leg = leg;
}

@Override
public void show() {
// TODO Auto-generated method stub
System.out.println("嘎");
}

@Override
public int leg() {
return this.leg;
}

}

------------------5

public class hai extends animal {

public hai(String name) {
super(name);
}

@Override
public void show() {
System.out.println("海豚");
}

}


---------------





public class test {

private static Object lu;

/**
 * @param args
 */
public static void main(String[] args) {
// TODO Auto-generated method stub
animal[] a=new animal[3];
a[0]=new cat("小猫",4);
a[1]=new duck("鸭子",2);
a[2]=new hai("海豚");
System.out.println("动物的名字"+"\t"+"腿数"+"\t\t"+"动物叫");
for(int i=0;i<a.length;i++)
{
if(a[i] instanceof lu) 
{
String name=a[i].getName();
int legnum=((lu)a[i]).leg();
//System.out.println(name+ "\t\t" +legnum+ "\t\t");
System.out.print(name + "\t\t" + legnum + "\t\t");
a[i].show();
}
else
{
String name=a[i].getName();
System.out.print(name+ "\t\t" +0+ "\t\t");
a[i].show();
}

}

}

}