泛型

package demo14;
import java.util.*;
public class l4_0 {
public static void main(String[] args) {
        ArrayList <String> myAlist=new  ArrayList <String>();
       Scanner input=new Scanner(System.in);
       String s;    
           int n=3;
      while(true){   
          s=input.next();    
          if(s.equals("q")){break;}
               myAlist.add(s);              }
      System.out.println( "线性列表中的值："+myAlist);
      if(n> myAlist.size( ))  {    
                 myAlist.add("55555") ;       }
      else    {   
                 myAlist.set(3, "wwe");                   }
      System.out.println( "修改后的线性列表中的值："+myAlist);    
      }       }

package demo14;
import java.util.*;
public class l4_1 {
    public static void main(String[] args) {
        Random r = new Random();
        ArrayList<Integer> mylist = new ArrayList<Integer>();
        for (int i = 0; i <= 9; i++) {
            int x = r.nextInt(30);
            mylist.add(x);
        }
        mylist.add(55555);
        System.out.println("初始化可变数组列表为：" + mylist);
        // 利用迭代器进行遍历
        Iterator it = mylist.iterator();
        System.out.println("遍历并修改可变数组列表为：");
        while (it.hasNext()) {
            System.out.print("：" + (Integer.parseInt(String.valueOf(it.next())) - 20));
        }
        System.out.println();
        it.remove();
        System.out.println("初始化可变数组列表为：" + mylist);
    }
}

package demo14;
import java.util.*;
public class l5 {
    public static void main(String[] args) {
         LinkedList <Integer> mylist=new LinkedList<Integer>();
         for(int i=1;i<=10;i++){
             mylist.add(i);
         }
         System.out.println(mylist);
         mylist.remove(4);
         System.out.println(mylist);
    }
}

package demo14;
import java.util.*;
public class l6 {
    public static void main(String[] args) {
        Map<String, String> hm = new  HashMap<String, String>();
        hm.put("301", "k1");
        hm.put("203", "k3");
        hm.put("102", "k2");
        hm.put("204", "k4");
        Set keys = hm.keySet();
        Iterator it = keys.iterator();
        while (it.hasNext()) {
            String x1 = (String) it.next();
            String x2 = (String) hm.get(x1);
            System.out.println(x1 + "    " + x2);
        }
        System.out.println("_____________");
    }
}

package demo14;
import java.util.*;
class goods {
    String s1;
    int x;
    double v;
    public goods() {
        s1 = "厂家名称";
        x = 0;
        v = 0;
    }
    public goods(String name, int x, double v) {
        s1 = name;
        this.x = x;
        this.v = v;
    }
}
public class l6_1 {
    public static void main(String[] args) {
        goods g1, g2, g3;
        String s1, s2, s3;
        s1 = "011";
        s2 = "012";
        s3 = "021";
        g1 = new goods("海尔冰箱", 400, 3000);
        g2 = new goods("美的冰箱", 300, 3000);
        g3 = new goods("海尔洗衣机", 200, 2000);
        HashMap<String, Object> goodsmap = new HashMap<String, Object>();
        goodsmap.put(s1, g1);
        goodsmap.put(s2, g2);
        goodsmap.put(s3, g3);
        Set keys = goodsmap.keySet();
        Iterator it = keys.iterator();
        while (it.hasNext()) {
            String x1 = (String) it.next();
            goods gx = (goods) goodsmap.get(x1);
            System.out.println(x1 + "    " + gx.s1 + "    " + gx.x + "     " + gx.v + "      总价值：" + gx.x * gx.v);
            System.out.println("-------------------------------------");
        }
    }
}

package demo14;
public class l1 {
    public static void main(String[] args) {
        //基本类常用形式=将字符串数字转乘数值 
                String s="123";
                int x=Integer.parseInt(s);
                System.out.println("输出转换后的整型数"+(x+1));
                System.out.println("输出未转换的数据"+(s+1));
        //封装整型类对象 =将 数值 转字符串
                int x1=123456;
                String sx1=String.valueOf(x1);
                System.out.println("输出转换后的整型数"+(sx1+11));
    }
}

package demo14;
public class l1 {
    public static void main(String[] args) {
        //基本类常用形式=将字符串数字转乘数值 
                String s="123";
                int x=Integer.parseInt(s);
                System.out.println("输出转换后的整型数"+(x+1));
                System.out.println("输出未转换的数据"+(s+1));
        //封装整型类对象 =将 数值 转字符串
                int x1=123456;
                String sx1=String.valueOf(x1);
                System.out.println("输出转换后的整型数"+(sx1+11));
    }
}

package demo14;
public class l1 {
    public static void main(String[] args) {
        //基本类常用形式=将字符串数字转乘数值 
                String s="123";
                int x=Integer.parseInt(s);
                System.out.println("输出转换后的整型数"+(x+1));
                System.out.println("输出未转换的数据"+(s+1));
        //封装整型类对象 =将 数值 转字符串
                int x1=123456;
                String sx1=String.valueOf(x1);
                System.out.println("输出转换后的整型数"+(sx1+11));
    }
}

package demo14;
import java.util.*;
class mystack {
    private LinkedList ld = new LinkedList();
    public void push(String s) {
        ld.addFirst(s);
    }
    public String pop() {
        return String.valueOf(ld.removeLast());
    }
    public Boolean isEmpty() {
        return ld.isEmpty();
    }
    public void print() {
        System.out.println("栈内存储情况：" + ld);
    }
}
public class l4 {
    public static void main(String[] args) {
        Scanner myin = new Scanner(System.in);
        mystack stack = new mystack();
        System.out.println("输入输入以q结束");
        while (true) {
            String s = myin.next();
            if (s.equals("q")) {
                break;
            }
            stack.push(s);
        }
        stack.print();
        System.out.println("演示先进先出的栈处理");
        while (!stack.isEmpty()) {
            System.out.print("   " + stack.pop());
        }
    }
}