1:像上转型=================
1.1定义抽象方法
public abstract class Dongwu {
public abstract void chi();
public abstract void jiao();
public abstract void shui();
}
1.2 定义两个实现类
public class Ji extends Dongwu {
@Override
public void chi() {
System.out.println("鸡吃");
}
@Override
public void jiao() {
System.out.println("鸡叫");
}
@Override
public void shui() {
System.out.println("鸡睡");
}
}
public class Zhu extends Dongwu {
@Override
public void chi() {
System.out.println("猪吃");
}
@Override
public void jiao() {
System.out.println("猪叫");
}
@Override
public void shui() {
System.out.println("猪睡");
}
}
1.3 主方法中调用
public class My {
void go(Dongwu d){
d.chi();
}
public static void main(String[] args) {
Ji j=new Ji();
Zhu z=new Zhu();
My m=new My();
m.go(j);
m.go(z);
}
}
==========================
2:变量初始化,基本类型是类变量时不用初始化,系统会自动初始化;如果在方法中的变量必须初始化,否则报错
public class T {
private int i;
public static void main(String[] args) {
T t=new T();
t.say();
System.out.println(t.i);
}
private void say(){
int j;
System.out.println(j);//j必须初始化,否则报错
}
}
==================
3:java 类的初始化,
先初始化变量,在初始化函数(包括构造函数)
设计模式总结1
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转载自zqs520.iteye.com/blog/2342643
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