List_java270

package tet;

import java.util.HashSet;
import java.util.Iterator;

public class Test {

    public static void main(String[] args) {
         HashSet<String> hs=new HashSet<String>();
         
         hs.add("jia");
         hs.add("hong");
         hs.add("ni ");
         hs.add("shi");
         hs.add("zui");
         hs.add("bang");
         hs.add("de");
         
         Iterator<String> it=hs.iterator();
         while(it.hasNext())
             System.out.println(it.next());
         
         
         HashSet<Integer> in=new HashSet<Integer>();
      
         in.add(65);
         in.add(1);
         in.add(85);
         Iterator<Integer> le=in.iterator();
         
         while(le.hasNext()){
             System.out.println(le.next());
         }
    }

}

package list_java270;

public class Test {

    
    public static void main(String[] args) {
           MyStack<String> str=new MyStack<String>();
           
           str.push("asdf");
           str.push("adf");
           
           str.push("dsfdf");
           str.push("aafdssdf");
           str.push("dsf");
           
           String element;
           while((element=str.pop())!=null){
               System.out.println(element);
           }
           
           MyStack<Integer> in=new MyStack<Integer>();
           in.push(12);
           in.push(1);
           in.push(85);
           
           Integer le;
           while((le=in.pop())!=null){
               System.out.println(le);
           }
    }

}

或者用HashSet实现

package list_java270;

import java.util.ArrayList;

public class MyStack<T> {
    
     private  ArrayList<T>  al=new ArrayList<T>();
     
     public void push(T e){
         al.add(e);
     }
     
     public T pop(){
         if(al.size()>0){
             return al.remove(al.size()-1);
         }
         else 
             return null;
     }
     
     public int size(){
         return al.size();
     }
     
}