[学习交流] 哈尔滨校区--技术交流--面向对象试题

洋葱头头

本帖最后由陈胜于 2016-2-19 23:33 编辑

大家新年快乐！！！    与大家分享四道多态方面的试题
1...
class test {
public static void main(String[] args) {
  Fu f = new Zi();
  Zi z = (Zi)f;
  f.show();
  z.show();
  System.out.println(f.output);
  System.out.println(z.output);
}
}
class Fu {
public  String output="1";
public void show(){
  output+=1;
}
}
class Zi extends Fu{
public  String output="1";
public void show(){
  output+=3;
}
}
2...
class test {
public static void main(String[] args) {
  Fu f = new Zi();
  Zi z = (Zi)f;
  f.show();
  z.show();
  System.out.println(f.output);
  System.out.println(z.output);
}
}
class Fu {
public  String output="1";
public void show(){
  output+=1;
}
}
class Zi extends Fu{
public void show(){
  output+=3;
}
}
3...
class test {
public static void main(String[] args) {
  Fu f = new Zi();
  Zi z = new Zi();
  f.show();
  z.show();
  System.out.println(f.output);
  System.out.println(z.output);
}
}
class Fu {
public  String output="1";
public void show(){
  output+=1;
}
}
class Zi extends Fu{
public  String output="1";
public void show(){
  output+=3;
}
}
4...
class test {
public static void main(String[] args) {
  Fu f = new Zi();
  Zi z = new Zi();
  f.show();
  z.show();
  System.out.println(f.output);
  System.out.println(z.output);
}
}
class Fu {
public  String output="1";
public void show(){
  output+=1;
}
}
class Zi extends Fu{
public void show(){
  output+=3;
}
}

陈胜 · 陈胜

同学给出的题都做出来多态这也就不糊涂了

renkuo023 · renkuo023

不明白啊。Zi z = (Zi)f; 是讲父类转换为为子类？

洋葱头头 · 洋葱头头

过年人少谢谢分享

嘉荫 · 嘉荫

renkuo023 发表于 2016-2-8 17:46
不明白啊。Zi z = (Zi)f; 是讲父类转换为为子类？

是的，这是向下转型。是对象的转型

我爱睡觉 · 我爱睡觉

我来看看

DDK畅 · DDK畅

晕了，虽然刚学完但是还是不太明白

tujiu888 · tujiu888

求详细解答

boboyuwu · boboyuwu

1...
class test {
public static void main(String[] args) {
  Fu f = new Zi();
  Zi z = (Zi)f;
  f.show();
  z.show();
  System.out.println(f.output);
  System.out.println(z.output);
}                               //上面的输出1
}                               //下面的打印出 133
class Fu {
public  String output="1";
public void show(){
  output+=1;
}
}
class Zi extends Fu{
public  String output="1";
public void show(){
  output+=3;
}
}
2...
class test {
public static void main(String[] args) {
  Fu f = new Zi();
  Zi z = (Zi)f;
  f.show();    //output=13
  z.show();       //  output=133
  System.out.println(f.output); //打印 output=133
  System.out.println(z.output);    //打印output=133
}
}
class Fu {
public  String output="1";
public void show(){
  output+=1;
}
}
class Zi extends Fu{
public void show(){
  output+=3;
}
}
3...
class test {
public static void main(String[] args) {
  Fu f = new Zi();
  Zi z = new Zi();
  f.show();
  z.show();
  System.out.println(f.output);                //打印1
  System.out.println(z.output);          //打印13
}
}
class Fu {
public  String output="1";
public void show(){
  output+=1;
}
}
class Zi extends Fu{
public  String output="1";
public void show(){
  output+=3;
}
}
4...
class test {
public static void main(String[] args) {
  Fu f = new Zi();
  Zi z = new Zi();
  f.show();
  z.show();
  System.out.println(f.output); //打印1
  System.out.println(z.output); //打印13
}
}
class Fu {
public  String output="1";
public void show(){
  output+=1;
}
}
class Zi extends Fu{
public void show(){
  output+=3;
}
}

youngrivers · youngrivers

new 对象

苗超维 · 苗超维

编译看左边运行看右边

yuchifeifan · yuchifeifan

陈胜发表于 2016-2-8 17:10
大家新年快乐！！！与大家分享四道多态方面的试题
1...
class test {

我怎么看着这四道题没区别呢

陈胜 · 陈胜

renkuo023 发表于 2016-2-8 17:46
不明白啊。Zi z = (Zi)f; 是讲父类转换为为子类？

1...
class test {
public static void main(String[] args) {
Fu f = new Zi();
Zi z = (Zi)f;
f.show();//编译看父类，运行看子类，子类output+3变为"13"，父类output不变
z.show();//子类output+3变为"133"  父类output不变
System.out.println(f.output);1
System.out.println(z.output);133
}
}
class Fu {
public  String output="1";
public void show(){
output+=1;
}
}
class Zi extends Fu{
public  String output="1";
public void show(){
output+=3;
}
}

2...
class test {
public static void main(String[] args) {
Fu f = new Zi();
Zi z = (Zi)f;
f.show();//编译看父类，运行看子类，子类继承父类output，子类调用父类output，output变为"13"
z.show();//子类调用父类output，output变为"133" 共用父类output
System.out.println(f.output);133
System.out.println(z.output);133
}
}
class Fu {
public  String output="1";
public void show(){
output+=1;
}
}
class Zi extends Fu{
public void show(){
output+=3;
}
}

3...
class test {
public static void main(String[] args) {
Fu f = new Zi();
Zi z = new Zi();
f.show();//编译看父类，运行看子类，父类output不变，子类output变为"13"
z.show();//z为另一个对象，子类调用父类output，子类output变为"13"
System.out.println(f.output);1
System.out.println(z.output);13
}
}
class Fu {
public  String output="1";
public void show(){
output+=1;
}
}
class Zi extends Fu{
public  String output="1";
public void show(){
output+=3;
}
}

4...
class test {
public static void main(String[] args) {
Fu f = new Zi();
Zi z = new Zi();
f.show();
z.show();
System.out.println(f.output);//编译看父类，运行看子类，子类调用父类output变为"13"
System.out.println(z.output);//z为另一个对象，子类调用父类output，子类调用output变为"13"
}
}
class Fu {
public  String output="1";
public void show(){
output+=1;
}
}
class Zi extends Fu{
public void show(){
output+=3;
}
}

陈胜 · 陈胜

DDK畅发表于 2016-2-10 06:53
晕了，虽然刚学完但是还是不太明白

1...
class test {
public static void main(String[] args) {
Fu f = new Zi();
Zi z = (Zi)f;
f.show();//编译看父类，运行看子类，子类output+3变为"13"，父类output不变
z.show();//子类output+3变为"133"  父类output不变
System.out.println(f.output);1
System.out.println(z.output);133
}
}
class Fu {
public  String output="1";
public void show(){
output+=1;
}
}
class Zi extends Fu{
public  String output="1";
public void show(){
output+=3;
}
}

2...
class test {
public static void main(String[] args) {
Fu f = new Zi();
Zi z = (Zi)f;
f.show();//编译看父类，运行看子类，子类继承父类output，子类调用父类output，output变为"13"
z.show();//子类调用父类output，output变为"133" 共用父类output
System.out.println(f.output);133
System.out.println(z.output);133
}
}
class Fu {
public  String output="1";
public void show(){
output+=1;
}
}
class Zi extends Fu{
public void show(){
output+=3;
}
}

3...
class test {
public static void main(String[] args) {
Fu f = new Zi();
Zi z = new Zi();
f.show();//编译看父类，运行看子类，父类output不变，子类output变为"13"
z.show();//z为另一个对象，子类调用父类output，子类output变为"13"
System.out.println(f.output);1
System.out.println(z.output);13
}
}
class Fu {
public  String output="1";
public void show(){
output+=1;
}
}
class Zi extends Fu{
public  String output="1";
public void show(){
output+=3;
}
}

4...
class test {
public static void main(String[] args) {
Fu f = new Zi();
Zi z = new Zi();
f.show();
z.show();
System.out.println(f.output);//编译看父类，运行看子类，子类调用父类output变为"13"
System.out.println(z.output);//z为另一个对象，子类调用父类output，子类调用output变为"13"
}
}
class Fu {
public  String output="1";
public void show(){
output+=1;
}
}
class Zi extends Fu{
public void show(){
output+=3;
}
}

陈胜 · 陈胜

tujiu888 发表于 2016-2-10 10:15
求详细解答

1...
class test {
public static void main(String[] args) {
Fu f = new Zi();
Zi z = (Zi)f;
f.show();//编译看父类，运行看子类，子类output+3变为"13"，父类output不变
z.show();//子类output+3变为"133"  父类output不变
System.out.println(f.output);1
System.out.println(z.output);133
}
}
class Fu {
public  String output="1";
public void show(){
output+=1;
}
}
class Zi extends Fu{
public  String output="1";
public void show(){
output+=3;
}
}

2...
class test {
public static void main(String[] args) {
Fu f = new Zi();
Zi z = (Zi)f;
f.show();//编译看父类，运行看子类，子类继承父类output，子类调用父类output，output变为"13"
z.show();//子类调用父类output，output变为"133" 共用父类output
System.out.println(f.output);133
System.out.println(z.output);133
}
}
class Fu {
public  String output="1";
public void show(){
output+=1;
}
}
class Zi extends Fu{
public void show(){
output+=3;
}
}

3...
class test {
public static void main(String[] args) {
Fu f = new Zi();
Zi z = new Zi();
f.show();//编译看父类，运行看子类，父类output不变，子类output变为"13"
z.show();//z为另一个对象，子类调用父类output，子类output变为"13"
System.out.println(f.output);1
System.out.println(z.output);13
}
}
class Fu {
public  String output="1";
public void show(){
output+=1;
}
}
class Zi extends Fu{
public  String output="1";
public void show(){
output+=3;
}
}

4...
class test {
public static void main(String[] args) {
Fu f = new Zi();
Zi z = new Zi();
f.show();
z.show();
System.out.println(f.output);//编译看父类，运行看子类，子类调用父类output变为"13"
System.out.println(z.output);//z为另一个对象，子类调用父类output，子类调用output变为"13"
}
}
class Fu {
public  String output="1";
public void show(){
output+=1;
}
}
class Zi extends Fu{
public void show(){
output+=3;
}
}

冷色 · 冷色

谢谢分享

qq358177556 · qq358177556

看完两道了,明天再看后两个,感谢分享

淡如水 · 淡如水

关注一下！

安卓必备 · 安卓必备

先回复再看的人有木有

TobyoTenma · TobyoTenma

分行很强大

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[学习交流] 哈尔滨校区--技术交流--面向对象试题

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