两个接口InterfaceA, InterfaceB:
public interface InterfaceA {
void methodA();
}
public interface InterfaceB {
void methodB();
}
两个类A,B分别实现此两个接口:
public class A implements InterfaceA {
public void methodA() {
System.out.println("A implements InterfaceA");}
}
public class B implements InterfaceB {
public void methodB() {System.out.println("B implements InterfaceB");}
}
父类Super中,两个接口作为实例变量
public class Super {
public InterfaceA a;
public InterfaceB b;
public void useMethodA() {
try{
a.methodA();
} catch (Exception ex){
System.out.println(ex.getMessage());
}
}
public void useMethodB(){
try{
b.methodB();
} catch (Exception ex){
System.out.println(ex.getMessage());
}
}
}
子类Son继承父类,(问题来乐!这时候public InterfaceA a = new A();可以成立的?new一个A的对象 然后直接可以赋给类型为InterfaceA的对象?)
public class Son extends Super {
public InterfaceA a = new A();
public InterfaceB b = new B();
}
写一个TestDrive, 编译成功,并正常调用了实现了接口的方法!
public class TestDrive {
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
Son s = new Son();
s.useMethodA();
s.useMethodB();
}
}
控制台输出:
null
null