Idea breakpoint debugging skills, multiple dynamic diagram package teaching package meeting.

One . How to start breakpoint debugging ？

With the development in depth , I feel more and more that efficient debugging methods are very important , But we usually type some code , Who will calm down and learn some debugging skills that seem useless ？ But this is exactly the difference between novice and veteran .

Breakpoint debugging is very simple , Just click idea Bugs above , Start debugging , As shown below .

This is certainly not the focus of this article , Just start .

Two . There are so many buttons in the debugging interface ？

Let's first introduce the interface .
I marked these areas Number , Let's focus on .

1. Return to the breakpoint location

1 Button No , This one doesn't use much , If you want to go back to the breakpoint from other places , Just click , as follows GIF Shown .

2. Step over

2 Button No , Speaking human words is to carry out line by line , Will not enter the method , As shown below .

3. Stepping into

3 Button No , You can enter our customized method , If it is the method of other class libraries, it will not enter , As shown below .

4,5. Forced entry , Step out

4 Number 5 Button No , The former can enter the deep method , Including the official source code , The latter is from the corresponding method , The demonstration is as follows .

6. Fallback breakpoint

6 Button No. 1 is very special , If your code doesn't call methods elsewhere , So it's gray , Can't use , There is only a deeper way , To be able to use , In fact, that is Regret , Many times, when debugging, we accidentally press it a little faster , It's easy to miss the place you want to see , Can I restart again ？ No , Use this drop frame That's all right. , The demonstration is as follows .

You can see , Here's the next step add, But it's not finished , Press this button , Again, before calling the method , But for operations such as database insertion , In fact, there is no retreat , The fallback here is only possible because the stack information is recorded .

But be careful , If one of your methods is called , If you want to go back, there is no way .

7. The breakpoint jumps to the cursor

7 Button No It doesn't use much , Mainly to quickly jump to the line pointed by the cursor , As shown below .

8. Expression evaluation

8 Button No. is used to calculate the expression , We simulate getting collections from a database , Query the corresponding element with an expression , As shown below .

9. Recovery procedure

9 The No. button is called Resume Program, It can jump to the specified breakpoint , We are 10 Xing He 100 Add a breakpoint to each line , You need to click this button to jump to 100 Line? ？ The answer is once , The first breakpoint will be at 10 Okay, stop , Click the change button to fly directly 90 Go to the first place 100 That's ok , As shown below .

10. Stop program

10 Button No. is to stop debugging , But notice , Even if you stop debugging , The program will continue to run , How do you want him to stop at the breakpoint ？ I'll talk about it later .

11. View all breakpoints

11 When button No. 1 is turned on, there is something else , The basic functions are shown in the figure below , It's mainly about setting up , View breakpoint information , Let's see , I will talk about the practical methods below .

12. Disable breakpoints

12 Button No. 1 is simple , Disable breakpoints temporarily , It is convenient for the program to continue , General coordination Resume Program.

13. other

13 No. is not a button , It's an area , There are many variables stored in it , It's convenient for us to check .

14 Button No. 1 was actually ignored by me before , This time take it out and talk about , stay watch It can monitor the changes of variables , Some students said , You can also see the variable column in the middle , But pull it out alone , It seems more convenient , The demonstration is as follows .

3、 ... and . There are so many debugging breakpoints ？

Ordinary line breakpoint debugging is omitted here , After all, it is the simplest , Everyone will .

1. Method breakpoint

Method breakpoints are not used for ordinary methods , The best use is on the interface , When we are debugging the source code , If a breakpoint is made on the interface , Go down again , You can jump directly to the implementation method of the implementation class , We don't need to find one by one .

In the case , There's an interface DemoInterface, It has two implementation classes , Let's take a look at the effect , The demonstration is as follows .

Be careful , Method breakpoint is a diamond symbol .

In fact, you can directly break points on interface methods , Jump directly to the corresponding implementation method , This is to slow down the demo .

2. Property breakpoint

Attribute breakpoints are set on attributes , We don't have to getter setter Break in the way , Put a breakpoint on the attribute , A small eye sign will appear , As shown below .

Right click on the eye to set .
We usually go through getter,setter Method set , So I will stay on these two methods .

to glance at GIF Show me .

3. Exception Breakpoint

The null pointer appears on the line BUG, We want to quickly locate where the null pointer appears , What should be done , The answer is , Exception Breakpoint ！ The demonstration is as follows .

Be careful , Abnormal breakpoint is a sign of lightning .

You can see , We made a null pointer breakpoint in the global , Whenever a null pointer appears , It will stop there , It's so convenient ！

4. Terminate breakpoint

We said earlier , Even if you stop the program , It won't let the code we run later cancel execution , Then I must cancel the execution, ok ？ Of course you can , Demo such as , Right click on the method stack , There is one Force Return, Then click Resumer Program, You can directly terminate and return .

5. Conditional breakpoints

I want to break when a certain condition is met , And don't want to go step by step , Is there any way ？ Of course. , Right click on the breakpoint , stay condition Fill in the corresponding conditions , The demonstration is as follows .

6. Flow breakpoint

When we use streams , It's hard to see what's done in the middle , But in fact idea Just help us solve , I use breakpoints to debug the following code , Show you .

In fact, you just need to find this button

 List<Integer> list = new ArrayList<>(Arrays.asList(1, 3, 3, 4, 4, 4, 5, 6, 78));
        List<Integer> collect = list.stream()
        		// First filter even numbers , Go back to the heavy , Back to the assembly 
                .filter(s -> s % 2 == 0)
                .distinct()
                .collect(Collectors.toList());

7. Multithreaded breakpoint

Show you two situations , Debugging under multithreading , Debug under scheduled tasks .

This demonstration is relatively simple , Maybe some students don't think so , You can try , If you use the default All To debug multithreaded programs , Maybe a thread ran away , No stay , This method can capture all running threads .

There is a benefit of debugging scheduled tasks like this , Even if we are in the process of debugging, the next task is time , And will not execute , Prevent interference caused by multiple scheduled task execution , I started the program one minute before the demonstration , every other 10 Print every second , But because the thread execution is suspended , Click the Resumer Program, It is found that there is no further implementation , But wait 10 Execute in seconds .

8. Remote breakpoint

This is ignored , Because there is really no remote breakpoint , If you have time to add , I feel dispensable .

In fact, everyone's life is a world , Even the most ordinary person has to fight for the world he lives in .