多态就是一个类中有多个同名方法,实现方式不一样,比如参数列表不同,或者父类和接口有同名方法,子类重写,重载。给个代码看看吧interface Say { public abstract void say(String name); }abstract class Person { public abstract void say(); }class Boy extends Person implements Say { @Override public void say() { System.out.print("Boy:"); } @Override public void say(String name) { System.out.println(name); } }class Girl extends Person implements Say { @Override public void say() { System.out.print("Girl:"); } @Override public void say(String name) { System.out.println(name); }}public class Main { public static void main(String[] args) { Boy boy = new Boy(); Girl girl = new Girl(); boy.say(); boy.say("Jack"); girl.say(); girl.say("Jones"); } }
DAO(Data Access Objects)是数据访问接口,主要跟数据库打交道,对数据库的操作基本上是放在DAO类中,这样是为了解耦合,便于代码的维护,如果对数据库操作出错了,我只要改一处就行了,不用多处改动。
public abstract void say(String name);
}abstract class Person {
public abstract void say();
}class Boy extends Person implements Say {
@Override
public void say() {
System.out.print("Boy:");
} @Override
public void say(String name) {
System.out.println(name);
}
}class Girl extends Person implements Say {
@Override
public void say() {
System.out.print("Girl:");
} @Override
public void say(String name) {
System.out.println(name);
}}public class Main {
public static void main(String[] args) {
Boy boy = new Boy();
Girl girl = new Girl(); boy.say();
boy.say("Jack");
girl.say();
girl.say("Jones"); }
}