idea breakpoint debugging

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

public class Test {
    public static void main(String[] args) {
        List<String> list =  new ArrayList<>();
        list.add("张三");
        list.add("李四");
        list.add("王五");
        String result = getResult(list);

        System.out.println(result);
    }

    public static String getResult (List<String> list){
        if (list == null|| list.size() == 0){
            return  null;
        }

        StringBuilder sb = new StringBuilder();
            for(String s : list){
                sb.append(s).append(" ");
            }
        Result = sb.toString String (); 

        return result.substring (0, result.length () -. 1); 
    } 


} 
to write such a program.　

Shortcut
 Alt + F8 to add a breakpoint Ctrl + D is quickly copy a row 



of small insects Debug --- that is

 under little insects can single-step operation. 

Each time you press F8, the program execution from the breakpoint, line by line, until the end of the run. 

resume 

 skip to the next breakpoint directly from the current breakpoint.

View all breakpoints

  

 

 

 Ban all breakpoints:

In the process of debugging, breakpoints do not know which problem. A line of code bug, want to skip all breakpoints,

 

After clicking the breakpoint changes from red to gray, then press F9 to jump over all the breaks you, will not stop 


conditional breakpoints

Assuming this break point, string s need only meet the content breakpoint Zhang

Ctrl + Shift + F8  

Conditions will come out a window

 

Enter java expression

Zhang string s content only meet breakpoint

 

After setting, to meet the conditions will stay,

list.add ( "Joe Smith"); stopover, the other did not stay. If the conditional breakpoint removed, it will stay.

 

 

Expression evaluation:

In the process of debugging breakpoints, after a certain breakpoint To see what the result is a calculated value

After starting debug, select the list. Then Alt + F8

Press Enter

We can see the value in the current list

 

 Run to the specified line:

 

Alt + F9 to run the specified breakpoint from the line.

 

 

setValue: set value

String result = getResult (list); 
Press F2 null fill in the list

 

To test

if (list == null|| list.size() == 0){
    return  null;
}
这段函数的输出是否一致