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Debug简介

• 什么是程序DeBug？

  • Debug，是程序开发人员必会的一项调试程序的技能。

  • 企业中程序开发和程序调试的比例为1:1.5，可以说如果你不会调试程序，你就没有办法从事编程工作。

• Debug能帮助我们做什么？

  1. 追踪代码的运行流程。
  2. 程序运行异常定位。
  3. 线上问题追踪。

• Debug对于程序学习者的意义

  1. 通过调试能够更好的查看程序的执行流程。
  2. 复杂的程序逻辑，通过老师的口述讲解，很难理解清楚，这个时候借助调试能够很好的帮助同学们理解程序。
  3. 定位问题，提高自我解决问题的能力。

IDEA中的Debug步骤

观察变量

• 查看变量有三种方式：

1. 程序区查看变量
2. Debugger的Variables中查看变量
3. 鼠标悬停到变量名上会弹出当前变量的值

/** * @Author: TEAM-AG * @Description: 调试基本介绍 * @Date: Created in 14:15 2020-05-28 * @Modified By: */public class Corgi_debug1 {
       public static void main(String[] args) {
           int num = 1;        System.out.println("num = " + num);        num ++;        System.out.println("num = " + num);        num ++;        System.out.println("num = " + num);        num ++;        System.out.println("num = " + num);        num ++;        System.out.println("num = " + num);        num ++;        System.out.println("num = " + num);        num ++;        System.out.println("num = " + num);        System.out.println("end...");    }}

步过和步入调试的使用

• 步过调试
  步过调试按钮（F8）
  
• 作用
  步过，一行一行地往下走，如果这一行上有方法不会进入方法。
  常用于调试过程中不想进入调用的方法体的情况。

• 步入调试

  步过调试按钮（F7）

  

• 作用

  步入，一行一行地往下走，如果这一行上有方法，则进入方法内部。

  一般用于进入自定义方法内，不会进入官方类库的方法。

import org.jetbrains.annotations.Contract;/** * @Author: TEAM-AG * @Description: 步过和步入调试的使用 * @Date: Created in 15:27 2020-05-28 * @Modified By: */public class Corgi_debug2 {
       public static void main(String[] args) {
           int a1 = add(1, 2);        System.out.println(a1);        int a2 = add(2, 3);        System.out.println(a1 + a2);        int result = a1 + a2;        System.out.println(result);    }   @Contract(pure = true)   private static int add(int a, int b){
           int result = a+b;        return result;   }}

强制步入和步出

import java.util.ArrayList;import java.util.Iterator;/** * @Author: TEAM-AG * @Description: 强制步入和步出&并发修改异常 * @Date: Created in 16:13 2020-05-28 * @Modified By: */public class Corgi_debug3 {
       public static void main(String[] args) {
           System.out.println("begin...");        operatorList();        System.out.println("end...");    }    private static void operatorList() {
           ArrayList
   
     list1 = new ArrayList<>();        list1.add("Corgi");        list1.add("CC");        list1.add("Jim");        list1.add("JACK");        //获取集合迭代器        Iterator
    
      iterator1 = list1.iterator();        while (iterator1.hasNext()) {
               String name = iterator1.next();            if(name.equals("Jim")) {
                   //改变集合元素个数                list1.add("JimAdd");            }        }    }}
    
   

计算表达式

/** * @Author: TEAM-AG * @Description: 计算表达式 * @Date: Created in 16:53 2020-05-28 * @Modified By: */public class Corgi_debug4 {
       public static void main(String[] args) {
           User user = new User("Corgi", "123456","超级管理员");        login(user);    }    private static void login(User user) {
           String userType = user.getUserType();        switch (userType) {
               case "超级管理员":                System.out.println("超级管理员业务逻辑");                break;            case "董事长":                System.out.println("董事长业务逻辑");                break;            case "经理":                System.out.println("经理业务逻辑");                break;            case "员工":                System.out.println("进入员工业务逻辑");                break;            default:                System.out.println("角色不存在");                break;        }    }}class User{
       private String userName;    private String pwd;    private String userType;    public User(String userName, String pwd, String userType) {
           this.userName = userName;        this.pwd = pwd;        this.userType = userType;    }    public String getUserName() {
           return userName;    }    public void setUserName(String userName) {
           this.userName = userName;    }    public String getPwd() {
           return pwd;    }    public void setPwd(String pwd) {
           this.pwd = pwd;    }    public String getUserType() {
           return userType;    }    public void setUserType(String userType) {
           this.userType = userType;    }}

条件断点

• 作用

  通过设置断点条件，在满足条件时，才停在断点处，否则直接运行。

/** * @Author: TEAM-AG * @Description: 条件断点 * @Date: Created in 17:10 2020-05-28 * @Modified By: */public class Corgi_debug5 {
       public static void main(String[] args) {
           for (int i = 1; i < 1000; i++) {
               execute(i);        }    }    private static void execute(int num) {
           int rs = ((num + 3) * 5 + 9) / num;        System.out.println(rs);    }}

多线程调试

案例1

/** * @Author: TEAM-AG * @Description: 多线程调试-案例1 * @Date: Created in 21:04 2020-05-28 * @Modified By: */public class Corgi_debug6 {
       public static void main(String[] args) {
           Thread thread1 = new Thread(new MyRunnable(), "曹操");        Thread thread2 = new Thread(new MyRunnable(), "刘备");        Thread thread3 = new Thread(new MyRunnable(), "孙权");        thread1.start();        thread2.start();        thread3.start();    }}class MyRunnable implements Runnable {
       @Override    public void run() {
           System.out.println(Thread.currentThread().getName() + "____进入");        try {
               Thread.sleep(1000);        } catch (InterruptedException e) {
               e.printStackTrace();        }        System.out.println(Thread.currentThread().getName() + "____离开");    }}

案例2

package Milk;/** * @Author: TEAM-AG * @Description:多线程调试-案例2 * @Date: Created in 10:58 2020-05-29 * @Modified By: */public class MainClass {
       public static void main(String[] args) {
           Box box = new Box();        Producer producer = new Producer(box);        Consumer consumer = new Consumer(box);        Thread thread1 = new Thread(producer, "生产者");        Thread thread2 = new Thread(consumer, "消费者");        thread1.start();        thread2.start();    }}

package Milk;/** * @Author: TEAM-AG * @Description: BOX * @Date: Created in 10:58 2020-05-29 * @Modified By: */public class Box {
       private int milk;    private boolean state = false;    public void put(int milk){
           System.out.println("put begin");        synchronized (this){
               if (state){
                   try{
                       System.out.println("put wait");                    wait();                }catch (InterruptedException e){
                       e.printStackTrace();                }                System.out.println("put wait end");            }            this.milk = milk;            System.out.println("送奶工将第" + this.milk + "瓶牛奶放入奶箱");            this.state = true;            notifyAll();        }        System.out.println("put end");    }    public void get() {
           System.out.println("get begin");        synchronized (this) {
               if (!state) {
                   try {
                       wait();                } catch (InterruptedException e) {
                       e.printStackTrace();                }            }            System.out.println("用户拿到第" + this.milk + "瓶牛奶");            this.state = false;            notifyAll();        }        System.out.println("get end");    }}

package Milk;/** * @Author: TEAM-AG * @Description: Producer * @Date: Created in 10:58 2020-05-29 * @Modified By: */public class Producer implements Runnable {
       private Box box;    public Producer(Box box) {
           this.box = box;    }    @Override    public void run() {
           for (int i=1; i<=5; i++){
               box.put(i);        }    }}

package Milk;/** * @Author: TEAM-AG * @Description: Consumer * @Date: Created in 10:58 2020-05-29 * @Modified By: */public class Consumer implements Runnable {
       private Box box;    public Consumer(Box box) {
           this.box = box;    }    @Override    public void run() {
           for (int i=1; i<=5 ;i++){
               box.get();        }    }}

更多信息

📍IDEA_Debug

https://www.bilibili.com/video/BV1LJ41187hu?p=1

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