老师,centos的压缩包坏了 可以重新上传一份吗

老师，为什么我Idea看不到抛出的类型？

问题一：“使用 this 关键字调用重载的构造方法，避免相同的初始化代码。”避免相同的初始化代码这句话什么意思？

问题二：this放在构造器第一行，在创建对象时它充当什么角色？

问题三：this到底有什么实际用途？

飞机还有背景图片在哪获取啊？      没有啊

unicode字符集为什么是65536, 2^16次方怎么来的

<template>
  <div id="app">
    <APIDemo2 />
  </div>
</template>

<script>
import APIDemo1 from './components/APIDemo1';
import APIDemo2 from './components/APIDemo2';
import HelloWorld from './components/HelloWorld'
export default {
  name: 'App',
  components:{
    HelloWorld,
    APIDemo1,
    APIDemo2,
  }
}
</script>

<style>
#app {
  font-family: 'Avenir', Helvetica, Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-align: center;
  color: #2c3e50;
  margin-top: 60px;
}
</style>

<template>
  <div>
    API
  </div>
</template>

<script>
    export default {
        name: "AIPDemo2",
      data(){
        return{

        }
      }
    }
</script>

<style scoped>

</style>

在equals未被改写的情况下，红色部分相同，结果是false，黄色部分相同,结果则是true，为什么？

public class TestEquals {
    public static void main(String[ ] args) {
        Person p1 = new Person(123,"高小七");
        Person p2 = new Person(123,"高小七");
        System.out.println(p1==p2);
        System.out.println(p1.equals(p2));
        String s1 = new String("尚学堂");
        String s2 = new String("尚学堂");
        System.out.println(s1==s2);
        System.out.println(s1.equals(s2)); 
    }
}
class Person {
    int id;
    String name;
    public Person(int id,String name) {
        this.id=id;
        this.name=name;
    }
}

老师为啥我的login方法点进去和别人的不一样。。。。。。

老师我代码应该没有写错呀，但是为什么还是会报错呢？

package com.bjsxt.network_programming;

import java.io.*;
import java.net.URL;

public class TestURL2 {
    public static void main(String[] args) throws IOException {
        /**
         * 网络爬虫
         * （1）从网络上获取资源www.baidu.com
         * （2）存储到本地
         */
//创建URL对象
        URL url=new URL("https://www.baifu.com/");//主页资源

        //获取字节流
        InputStream is=url.openStream();
        //缓存流
        BufferedReader br=new BufferedReader(new InputStreamReader(is,"utf-8"));
        //存储到本地
        BufferedWriter bw=new BufferedWriter(new OutputStreamWriter(new FileOutputStream("index.html"),"utf-8"));
        //边读边写
        String line =null;
        while ((line=br.readLine())!=null){
            bw.write(line);
            bw.newLine();
            bw.flush();
        }
        //关闭流

        bw.close();
        br.close();

    }
}

Exception in thread "main" java.net.ConnectException: Connection timed out: connect

at java.net.DualStackPlainSocketImpl.connect0(Native Method)

at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)

at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)

at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)

at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)

at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)

at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)

at java.net.Socket.connect(Socket.java:589)

at sun.security.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:666)

at sun.security.ssl.BaseSSLSocketImpl.connect(BaseSSLSocketImpl.java:173)

at sun.net.NetworkClient.doConnect(NetworkClient.java:180)

at sun.net.www.http.HttpClient.openServer(HttpClient.java:463)

at sun.net.www.http.HttpClient.openServer(HttpClient.java:558)

at sun.net.www.protocol.https.HttpsClient.<init>(HttpsClient.java:264)

at sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:367)

at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(AbstractDelegateHttpsURLConnection.java:191)

at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1156)

at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1050)

at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:177)

at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1564)

at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1492)

at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:263)

at java.net.URL.openStream(URL.java:1045)

at com.bjsxt.network_programming.TestURL2.main(TestURL2.java:17)

Process finished with exit code 1

图片加载不出来，格式正确   换了图片也不行，是需要解码？我记得不用吧

<template>
  <div>
    <p>{{count}}</p>
    <button @click="setCountHandler">按钮</button>
    <a :href="url">百度</a>
    <p v-for="(item,index) in names" :key="index">{{item}}</p>
    <button @click="addNames">按钮</button>
  </div>
</template>

<script>
    export default {
        name: "APIDemo1",
      data(){
          return{
            count:10,
            url:"http://www.baidu.com",
            names:["a","b","c","d"]
          }
      },
      methods:{
          setCountHandler(){
            this.count+=1
          },
          addNames(){
            let currentName = ["e","f"];
            let totalNames = this.name.concat(currentName);
            this.names = totalNames;
          }
      }
    }
</script>

<template>
  <div class="hello">
   {{ msg }}
    <p v-html="room"></p>
    <a v-bind:href="links.url">{{ links.title }}</a>
    <p>{{1+1}}</p>
    <div>
      <template v-if="flag">
        <p>孙悟空</p>
        <p>唐僧</p>
        <p>猪八戒</p>
        <p>沙和尚</p>
      </template>
      <template v-else>
        <p>六耳猕猴1</p>
        <p>六耳猕猴2</p>
        <p>六耳猕猴3</p>
        <p>六耳猕猴4</p>
      </template>
    </div>
    <p v-show="flag">我是show</p>
    <p v-for="(item,index) in names" v-bind:key="index">{{ item }}</p>
    <p v-for="(item,name,index) in obj" v-bind:key="index">{{name}}:{{item}}: {{index}}</p>
    <p>{{count}}</p>
    <button v-on:mouseover="addCountHandler(10,$event)">按钮</button>
  </div>

</template>

<script>
export default {
  name: 'HelloWorld',
  data () {
    return {
      msg: 'HelloWorld',
      flag:true,
      count:0,
      room:"<h2>只是一个h2标签</h2>",
      names:["zhou","jia","quan"],
      obj:{name:"邹雅婷",age:20,sex:"女"},
      id:1002,
      links:{
        title:"周家泉的小屋",
        url:"http://www.baidu.com",
      }
    }
  },
  methods:{
    addCountHandler(data,event){
      console.log(event)
      this.count += data
    }
  }
}
</script>

这个event事件一直报错

请问提供的源码全码？为什么发过来的源码和视频里完全不一样，缺少很多文件

             这是什么错误啊  编译通过了