IntelliJ IDEA Debug调试案例二

柔情只为你懂 2022-06-08 04:23 179阅读 0赞

*   *  第一个debug
        
         *  代码块
         *  Run
            
             *  分析错误
         *  Debug
            
             *  分析错误
         *  正确代码
     *  第二个debug
        
         *  代码块
         *  Run
            
             *  分析错误
         *  Debug
            
             *  分析错误
         *  正确代码

## 第一个debug ##

> java.text.ParseException: Unparseable date  
> **日期解析异常**

### 代码块 ###

@RunWith(SpringRunner.class)
    @SpringBootTest
    public class LogParserTest { 
        SimpleDateFormat sdf =   new SimpleDateFormat( " yyyy-MM-dd HH:mm:ss " );
    
        @Autowired
        LogParser logParser;
        List<LogModel> logs = null;
    
        @Before
        public void before() {
            logs = new ArrayList<>();
    
            try {
                LogModel logModel1 = new LogModel(sdf.parse("2017-09-07 11:32:43"), "Notepad_AddLogmessage execution started-4");
                LogModel logModel2 = new LogModel(sdf.parse("2017-09-01 10:32:43"), "Notepad_AddLogmessage execution-3");
                LogModel logModel3 = new LogModel(sdf.parse("2017-01-07 13:32:43"), "Notepad_AddLogmessage execution-1");
                LogModel logModel4 = new LogModel(sdf.parse("2017-01-07 16:32:43"), "Notepad_AddLogmessage execution ended-2");
                logs.add(logModel1);
                logs.add(logModel2);
                logs.add(logModel3);
                logs.add(logModel4);
    
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    
        @Test
        public void parse() throws Exception {
            //logParser.parse(logs);
            System.out.println(logs.get(0).getMessage());
        }
    }

### Run： ###

java.text.ParseException: Unparseable date: "2017-09-07 11:32:43"
        at java.text.DateFormat.parse(DateFormat.java:366)
        at com.dxc.leap.raas.uipath.orchestrator.service.LogParserTest.before(LogParserTest.java:37)

**图1：**  
![这里写图片描述][SouthEast]

**图2：**  
![这里写图片描述][SouthEast 1]

#### 分析错误 ####

检查日期格式：2017-09-07 11:32:43 对应 yyyy-MM-dd HH:mm:ss  
当时不理解为什么会出错，于是选择debug运行

### Debug ###

![这里写图片描述][SouthEast 2]

#### 分析错误 ####

当时debug运行完还是没找到错误源头，之后无意中发现SimpleDateFormat构造的时间格式前后有空格，所以无法解析。

> new SimpleDateFormat( ” yyyy-MM-dd HH:mm:ss ” );

### 正确代码 ###

去掉日期格式中的前后空格

SimpleDateFormat sdf = new SimpleDateFormat( "yyyy-MM-dd HH:mm:ss" );

## 第二个debug ##

> java.lang.NullPointerException  
> **空指针异常**

### 代码块 ###

@RunWith(SpringRunner.class)
    @SpringBootTest
    public class LogParserTest { 
        SimpleDateFormat sdf =   new SimpleDateFormat( "yyyy-MM-dd HH:mm:ss" );
        @Autowired
        LogParser logParser;
        List<LogModel> logs = null;
    
        @Before
        public void before() {
            try {
                LogModel logModel1 = new LogModel(sdf.parse("2017-09-07 11:32:43"), "Notepad_AddLogmessage execution started-4");
                LogModel logModel2 = new LogModel(sdf.parse("2017-09-01 10:32:43"), "Notepad_AddLogmessage execution-3");
                LogModel logModel3 = new LogModel(sdf.parse("2017-01-07 13:32:43"), "Notepad_AddLogmessage execution-1");
                LogModel logModel4 = new LogModel(sdf.parse("2017-01-07 16:32:43"), "Notepad_AddLogmessage execution ended-2");
                logs.add(logModel1);
                logs.add(logModel2);
                logs.add(logModel3);
                logs.add(logModel4);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    
        @Test
        public void parse() throws Exception {
            //logParser.parse(logs);
            System.out.println(logs.get(0).getMessage());
        }
    }

### Run ###

java.lang.NullPointerException
        at com.dxc.leap.raas.uipath.orchestrator.service.LogParserTest.before(LogParserTest.java:37)

![这里写图片描述][SouthEast 3]

#### 分析错误 ####

从错误提示中提示第37行空指针异常，那么意味着logs为null，再结合IntelliJ IDEA的运行提示中可以看出，第28行显示logs = null,就是说logs没有创建，需要new ArrayList（）。

### Debug ###

**图1：**  
![这里写图片描述][SouthEast 4]

**图2：**  
![这里写图片描述][SouthEast 5]

#### 分析错误 ####

从debug错误提示中可以看出，logs为null。

### 正确代码 ###

创建logs而不是声明logs，添加代码行logs = new ArrayList<>();  
代码如下：

@RunWith(SpringRunner.class)
    @SpringBootTest
    public class LogParserTest { 
        SimpleDateFormat sdf =   new SimpleDateFormat( "yyyy-MM-dd HH:mm:ss" );
        @Autowired
        LogParser logParser;
        List<LogModel> logs = null;
    
        @Before
        public void before() {
            try {
                logs = new ArrayList<>();
                LogModel logModel1 = new LogModel(sdf.parse("2017-09-07 11:32:43"), "Notepad_AddLogmessage execution started-4");
                LogModel logModel2 = new LogModel(sdf.parse("2017-09-01 10:32:43"), "Notepad_AddLogmessage execution-3");
                LogModel logModel3 = new LogModel(sdf.parse("2017-01-07 13:32:43"), "Notepad_AddLogmessage execution-1");
                LogModel logModel4 = new LogModel(sdf.parse("2017-01-07 16:32:43"), "Notepad_AddLogmessage execution ended-2");
                logs.add(logModel1);
                logs.add(logModel2);
                logs.add(logModel3);
                logs.add(logModel4);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    
        @Test
        public void parse() throws Exception {
            //logParser.parse(logs);
            System.out.println(logs.get(0).getMessage());
        }

再次debug运行后：  
![这里写图片描述][SouthEast 6]

此时logs不再是为null

[SouthEast]: /images/20220608/40fe3cdd68f04c40bb6ccdba3601f8aa.png
[SouthEast 1]: /images/20220608/dccf11cad3ed4a2683e2b914f7535a03.png
[SouthEast 2]: /images/20220608/053e8f929e3442d2b64e186b785e554e.png
[SouthEast 3]: /images/20220608/b1e8011d50da4dc48ad8d295f5d6a96d.png
[SouthEast 4]: /images/20220608/91ca217ec95a4b13903733c783598472.png
[SouthEast 5]: /images/20220608/9f9e6a3d83d848d792a65bad289ebb24.png
[SouthEast 6]: /images/20220608/8b0bc3b2f2cc488582c8b655cb766de2.png