[论坛提问] 黑马入学考试两道题不会了，求学长们指教

灬Wonder

7、有一组奖品：{macBookPro：8988?，三星note7：5695?，小米4：2688?，联想P612：866?，iphone7：5688?}（每个奖品只有一个，并且同一时间只能有一个人抽奖）；开启两个线程A、B模拟两个人抽奖的过程（每个人抽取的次数不做限制），直到奖品抽完为止，打印出每个人抽到的奖品和价值金额；

8、接收用户从控制台输入的一个区间，在该区间范围内（包含左右边界），随机生成20个不重复的数字（若用户输入该区间范围小于20，则提示用户重新给定区间）：

a.统计出所有的偶数，输出到控制台；

b.将剩下的数字按照降序排序后存放到当前项目下，命名为number.txt,每个数用“-” 隔开; 比如：13-1-5-27-23

示例

控制台提示：请输入范围大于20的区间，比如“10-35”
用户输入： 10-18
控制台提示：对不起，您输入的区间范围小于20，请重新输入
用户输入： 5-26
控制台提示：偶数有：8，12，6，24
控制台提示：将奇数写入number.txt 成功

用户名已不存在 · 用户名已不存在

没人吗？求各位哥哥姐姐

用户名已不存在 · 用户名已不存在

实在是不会啊，求教求教

sb123456 · sb123456

zmanx · zmanx

初级选手报道,表示看不懂啊

用户名已不存在 · 用户名已不存在

第一题

import java.util.Arrays;
import java.util.Random;

public class ceshione {

public static void main(String[] args) {
Ticket2 runTicekt = new Ticket2();
         Thread th1 = new Thread(runTicekt, "A");
      Thread th2 = new Thread(runTicekt, "B");
      th1.start();
      th2.start();
}
}

class Ticket2 implements Runnable {
String[] s = { "macBookPro：8988","三星note7：5695","小米4：2688","联想P612：866","iphone7：5688" };

Object mutex = new Object();// 锁

public void chou() {
synchronized (mutex)// 当操作的是共享数据时,
{

Random random = new Random();
if(s.length - 1==0){
String num[]=s[0].split("：");
System.out.println(Thread.currentThread().getName() + "抽到了" + num[0]+" 价值："+num[1]);
s[0] = s[s.length - 1];

// 数组缩容
s = Arrays.copyOf(s, s.length - 1);
}
else{

int a = random.nextInt(s.length - 1);
String num[]=s[a].split("：");
System.out.println(Thread.currentThread().getName() + "抽到了" + num[0]+" 价值："+num[1]);
s[a] = s[s.length - 1];
// 数组缩容
s = Arrays.copyOf(s, s.length - 1);
}

}
}

@Override
public void run() {
// TODO Auto-generated method stub
while (s.length > 0) {

chou();
if(s.length==1){
return;
}
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}

}

}

}

yourtear · yourtear

11111111111

kimoti · kimoti

第一题

public class Prize {
private String name;
private int value;

public Prize(String name,int value){
      this.name = name;
      this.value = value;
}

public String getName() {
      return name;
}
public void setName(String name) {
      this.name = name;
}
public int getValue() {
      return value;
}
public void setValue(int value) {
      this.value = value;
}

}

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class LuckyDraw {
private List<Prize> prizes = new ArrayList<Prize>();

public LuckyDraw(){
      Prize macBook = new Prize("macBookPro",8988);
      Prize note7 = new Prize("note7",5695);
      Prize xiaomi = new Prize("xiaomi4",2688);
      Prize legend = new Prize("legendP612",866);
      Prize iphone7 = new Prize("iphone7",5688);

      prizes.add(macBook);
      prizes.add(note7);
      prizes.add(xiaomi);
      prizes.add(legend);
      prizes.add(iphone7);
}

public synchronized Prize draw(){
      Random r = new Random();
      if(prizes.size()==0){
         return null;
      }
      int index = r.nextInt(prizes.size());
      System.out.println("size========="+prizes.size());
      System.out.println("index========"+index);
      return prizes.remove(index);
}

}

public class Draw implements Runnable{

private LuckyDraw luckyDraw;

public Draw(LuckyDraw luckyDraw){
      this.luckyDraw = luckyDraw;
}

@Override
public void run() {
      Prize prize = luckyDraw.draw();
      while(prize!=null){
         System.out.println(Thread.currentThread().getName()+" draw "+prize.getName()+",value="+prize.getValue());
         prize = luckyDraw.draw();
      }
}

}

public class TestDraw {

public static void main(String[] args) throws Exception{
      LuckyDraw luckyDraw =  new LuckyDraw();
      Draw runnable = new Draw(luckyDraw);

      Thread draw1 = new Thread(runnable);
      Thread draw2 = new Thread(runnable);

      draw1.start();
      draw2.start();

}

}

水墨画 · 水墨画

手痒写了一下第二题

import java.io.File;
import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Scanner;
import java.util.TreeSet;

public class day4 {
public static void main(String[] args) {
      Scanner scanner=new Scanner(System.in);
      int limitLeft=0;
      int limitRight=0;
      StringBuffer writebuffer=new StringBuffer();
      List<String> wriList=new ArrayList<String>();

      System.out.println(" 请输入范围大于20的区间，比如“10-35“");
      //获取区间
      while(true) {

            String inpudata=scanner.next();
            limitLeft=Integer.valueOf(inpudata.split("-")[0]);
            limitRight=Integer.valueOf(inpudata.split("-")[1]);

            if(limitRight-limitLeft>=20) {
                  //System.out.println(limitRight-limitLeft);
                  scanner.close();
                  break ;
            }
            System.out.println("对不起，您输入的区间范围小于20，请重新输入");

      }

      //获取符合区间的随机数
      TreeSet<Integer> result=new TreeSet<>();
      while(result.size()<20){
         int ramod=(int)(Math.random()*limitRight);
         if(ramod>=limitLeft&&ramod<=limitRight) {
            result.add(ramod);
         }
      }

      //区分选出来的奇数和偶数
      System.out.print("偶数有：");
      Iterator<Integer> it=result.iterator();
      while(it.hasNext()) {
         int temp=it.next();
         if((temp%2)==0) {
            System.out.print(temp+" ");
         }
         else {
            wriList.add(Integer.toString(temp));
         }
      }

      //将奇数写入文件
      try {
         File file=new File("number.txt");
         FileOutputStream fp=new FileOutputStream(file);
         OutputStreamWriter writer=new OutputStreamWriter(fp);

         int oddNum=wriList.size();
         for(int i=0;i<oddNum;i++) {
            writebuffer.append(wriList.get(oddNum-1-i)+(i==oddNum-1?"":"-"));
         }


         writer.append(writebuffer);

         writer.close();
         fp.close();

         System.out.print("将奇数写入number.txt 成功");
      } catch (Exception e) {
         e.printStackTrace();
      }


}

}

lion86 · lion86

靠就业班的考试题吗？

a469517790 · a469517790

package com.heima.Test;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;

public class Test2 {
//创建map集合，
static HashMap<String, Integer> hm = new HashMap<>(); //static修饰可以让所有线程共享该集合

//添加集合元素，放入静态代码块
static{
hm.put("macBookPro", 8988);
hm.put("三星note7", 5695);
hm.put("小米4", 2688);
hm.put("联想", 866);
hm.put("iphone", 5688);
}

public static void main(String[] args) {

new Thread("线程一"){
public void run(){
while(hm.size() > 0){
synchronized (Test2.class) { //同步代码块，放在while之后，不然一条线程就能把奖品抽完
try {
Thread.sleep(1000); //可加可不加
} catch (InterruptedException e) {

e.printStackTrace();
}
Set<String> arr = hm.keySet(); //获得键的集合
Iterator<String> it = arr.iterator(); //获得迭代器
if(arr.size() > 0){
String getPhone = it.next(); //获得键，即抽到手机
int value = hm.get(getPhone); //通过键获得值，即手机价格
System.out.println(getName() + "抽到了" + getPhone + ",价格是" + value);
hm.remove(getPhone); //移除集合元素
}
}
}
}
}.start();

new Thread("线程二"){
public void run(){
while(hm.size() > 0){
synchronized (Test2.class) {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {

e.printStackTrace();
}
Set<String> arr = hm.keySet();
Iterator<String> it = arr.iterator();
if(arr.size() > 0){
String getPhone = it.next();
int value = hm.get(getPhone);
System.out.println(getName() + "抽到了" + getPhone + ",价格是" + value);
hm.remove(getPhone);
}
}
}
}
}.start();
}

}

a469517790 · a469517790

KyneZhk 发表于 2017-2-6 22:23
第一题:定义抽奖箱类,实现Runnable
[mw_shl_code=applescript,true]package com.demo5;

看来你用arraylist 比我用hashmap 来的简单

a469517790 · a469517790

public static void main(String[] args) throws IOException {
Scanner sc = new Scanner(System.in);
Random rd = new Random();
String line;
String[] arr;
int firstNum;
int lastNum;
ArrayList<Integer> list = new ArrayList<>();
FileWriter fw = new FileWriter("number.txt");
System.out.println("请输入一个范围大于20的区间,比如\"10-35\"");
while(true){
line = sc.nextLine();
arr = line.split("-");
firstNum = Integer.valueOf(arr[0]);
// System.out.println(firstNum);
lastNum = Integer.valueOf(arr[1]);
// System.out.println(lastNum);
if((lastNum - firstNum) < 20){
System.out.println("对不起，您输入的区间范围小于20，请重新输入");
continue;
}else{
for(int i = firstNum; i <= lastNum; i++){
if(i % 2 == 0){
list.add(i);
}else{
if(i == lastNum || i ==lastNum - 1){
fw.write(String.valueOf(i));
}else {
fw.write(i + "-");
}
}
}
fw.close();
System.out.print("偶数有：");
for (int i = 0; i < list.size(); i++) {
if(i == list.size() - 1){
System.out.print(list.get(i));
}else{
System.out.print(list.get(i) + ",");
}
}
System.out.println();
System.out.println("将奇数写入number.txt 成功");
break;
}

}
}

}

a469517790 · a469517790

刚刚那遍要求看错了

public class Test4 {
public static void main(String[] args) throws Exception {
Scanner sc = new Scanner(System.in);
Random rd = new Random();
String line;
String[] arr;
int firstNum;
int lastNum;
int num;
ArrayList<Integer> list3 = new ArrayList<>(); //放奇数
ArrayList<Integer> list2 = new ArrayList<>(); //放偶数
ArrayList<Integer> list = new ArrayList<>();
BufferedWriter bw = new BufferedWriter(new FileWriter("number.txt"));
System.out.println("请输入一个范围大于20的区间,比如\"10-35\"");
while(true){
line = sc.nextLine();
arr = line.split("-");
firstNum = Integer.valueOf(arr[0]);
// System.out.println(firstNum);
lastNum = Integer.valueOf(arr[1]);
// System.out.println(lastNum);
if((lastNum - firstNum) < 20){
System.out.println("对不起，您输入的区间范围小于20，请重新输入");
continue;
}else{
while (list.size() <= 20) {
num = rd.nextInt(lastNum - firstNum) + firstNum;
if(!list.contains(num))
list.add(num);
}
for(Integer i : list){
if(i % 2 == 0){
list2.add(i);
}else if (i % 2 == 1){
list3.add(i);
/*if(i == lastNum || i ==lastNum - 1){
fw.write(String.valueOf(i));
}else {
fw.write(i + "-");
}*/
}
}
System.out.print("偶数有：");
for (int i = 0; i < list2.size(); i++) {
if(i == list2.size() - 1){
System.out.print(list2.get(i));
}else{
System.out.print(list2.get(i) + ",");
}
}
System.out.println();
Collections.sort(list3);
for (int i = list3.size() - 1; i >= 0; i--) {
if(i == 0){
bw.write(list3.get(i).toString());
}else
bw.write(list3.get(i) + "-");
}
bw.close();
System.out.println("将奇数写入number.txt 成功");
break;
}

}
}
}

黑马^123 · 黑马^123

KyneZhk 发表于 2017-2-6 22:23
第一题:定义抽奖箱类,实现Runnable
[mw_shl_code=applescript,true]package com.demo5;

怎么找不到concurrent

黑马^123 · 黑马^123

KyneZhk 发表于 2017-2-15 16:53

Lock在api中找不到

newu · newu

package com

蔺小帅 · 蔺小帅

留个坐标，学习学习

xiaoxipeng · xiaoxipeng

留下几号，这是就业班的考试题目吗

张昊123 · 张昊123

7期的学员表示看不懂，太难，压力山大

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[论坛提问] 黑马入学考试两道题不会了，求学长们指教

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