public class Client {

/**
* <pre>
* a）在main函數(shù)中聲明一個(gè)數(shù)組，該數(shù)組可以存儲(chǔ)B和C類，并用B和C類初始化該數(shù)組，
* 并通過(guò)循環(huán)來(lái)調(diào)用該數(shù)組中每個(gè)存儲(chǔ)元素的print()方法。
*
* b）在main函數(shù)中聲明另一個(gè)數(shù)組，該數(shù)組可以存儲(chǔ)B和C類，并用B和C類初始化該數(shù)組，
* 并通過(guò)循環(huán)來(lái)調(diào)用該數(shù)組中每個(gè)存儲(chǔ)元素的show()方法。
* </pre>
*
* @param args
*/
public static void main(String[] args) {
// Array a = new Array[2];

Object[] a = new Object[3];
a[0] = new B();
a[1] = new C();
a[2] = new B();

Object[] b = new Object[3];
b[0] = new B();
b[1] = new C();
b[2] = new B();

A tempa = null;
for (int i = 0; i < a.length; i++) {
tempa = (A) a[i];
tempa.print();
}

IA tempb = null;
for (int j = 0; j < b.length; j++) {
tempb = (IA) b[j];
tempb.show();
}
}

}

abstract class A {
public abstract void print();
}

interface IA {
public abstract void show();
}

class B extends A implements IA {

@Override
public void print() {
System.out.println("Class B");
}

public void show() {
System.out.println("I'm B, implements IA");
}

}
class C extends A implements IA {

public void show() {
System.out.println("I'm C, implements IA");
}

@Override
public void print() {
System.out.println("Class C");
}

}

-----------Console--------------------------
Class B
Class C
Class B
I'm B, implements IA
I'm C, implements IA
I'm B, implements IA

感謝上面解答 但還是不懂 呵呵