java I

今天闲着就想起学学java，还不错，挺顺畅的，主要是多态之类的。

E1:

what.java

import ok.*;
 class abc extends ok{
 	public abc()
 {
  System.out.print("abc() called;\n");
 }
 
 public void x()
 {
  System.out.print("abc.x() called;\n");
 }
 public void x2()
 {
  System.out.print("abc.");
  super.x();
 }
}
 class abc2 extends ok{
 private int x=0;
 private int y=0;
 
 public abc2()
 {
  System.out.print("abc2() called;\n");
 }
 
 public void x()
 {
  System.out.print("abc2.x() called;\n");
 }
 public void x2()
 {
  System.out.print("abc2.");
  super.x();
 }
}
 public class what{
 public static void main(String args[])
 {
  try{
  ok[] y={new abc2(),new abc(),new abc2()};
  for(ok e : y){
   e.x();
   try{
    ((abc)e).x2();
    }
    catch(Exception x){
     ((abc2)e).x2();
     //x.printStackTrace(System.out);
     //throw x;
    }
  }
 }catch(Exception x){
     System.out.print("The upper Deal!\n");
     x.printStackTrace(System.out);
    }
 }
}

./ok/ok.java

package ok;
abstract public class ok{
 protected int ac=1;
 protected int bc=1;
 public ok()
 {
   System.out.print("ok() called;\n");
 }
 /*public ok(int abc,int ca)
 {
  this.ac=abc;
  this.bc=ca;
  System.out.println(ac);
  System.out.println(bc);
 }*/
 public void giveAnswer(){}
 
 public void x(){
  System.out.print("super of x() called;\n");
 }
}

output:

ok() called;
abc2() called;
ok() called;
abc() called;
ok() called;
abc2() called;
abc2.x() called;
abc2.super of x() called;
abc.x() called;
abc.super of x() called;
abc2.x() called;
abc2.super of x() called;

 

E2:

imp.java

interface Inte{
 void ok();
}
 class Abc implements Inte{
 public void ok(){
   System.out.println("Abc.ok() called!"); 
 }
}
class Problem implements Inte{
 public void ok(){
   System.out.println("Problem.ok() called!"); 
 }
}
public class imp{
 public static void main(String args[]){
   Inte[] temp={new Abc(),new Problem()};
   for(Inte e : temp){
    e.ok();
   }
 }
}

 output:

Abc.ok() called!
Problem.ok() called!