Process control statement structure:

1. Sequential structure

2. Branch Structure:

if… Else series, switch.. A case series

3. Loop structure: Some statements that need to be repeated

(1) the for loop

for(;;) {loop body blocks, that is, code that needs to be executed repeatedly; } for(initialize expression; Cyclic condition expression; Iterating expression){loop body statement block, that is, code that needs to be executed repeatedly; }Copy the code
  1. Two for loops; Must write, no more, no less
  2. Initialize an expression, usually by declaring a loop variable, and initialize
  3. The expression of a loop condition is used to control the end of the loop. If the condition is true, the loop can be used; if the condition is not true, the loop should be ended
  4. An iterative expression used to modify the value of a loop variable
  5. Execution process :(1) first execute the initialization expression (2) judge the loop condition expression, if the condition is true, continue the loop, otherwise end the loop.
  6. (1) The body statement of the for loop may not be executed once, that is, the first judgment condition is not valid; (2) The for loop may loop indefinitely, the loop condition may not be written, or the condition may never hold.
  7. Break: Indicates the end of the current loop in switch

(2) the while loop

We can consider using a while loop when the number of loops is not obvious and only the conditions of the loop are known. You can also use “for”.

Grammatical structure

While (loop condition){loop body statement block; }Copy the code

Note:

  1. The loop condition written in while() must be Boolean; if true, the loop body is executed; otherwise, the loop is terminated
  2. While () does not follow;

Execution process:

  1. The while() loop executes {} if the condition is true; otherwise, it terminates.
  2. After executing the body block, return to 1

Remind:

  • The body of a while loop may not be executed at all.

(3)do… The while loop

When this scenario is encountered: the loop body is executed at least once. Consider using do… while

Grammatical structure:

Do {loop body statement block; }while(loop condition); // Don't forget the semicolon after while()Copy the code

Description:

  1. While if the condition is true, repeat the body of the loop. If the condition is not true, end the loop
  2. While (loop condition); Behind;

Execution process:

  1. Execute the loop body block in do{} once
  2. Then judge the condition of the while. If the condition is true, continue, otherwise end
  3. If true, execute the loop body block in do{} again, then repeat 2 and 3

Remind:

  • do… The body block of the while structure executes once anyway, at least once.

    break:

    (1)switch

    (2) Loop: for,while,do… The while. Function: Ends the current switch or loop

Continue :(rarely used in actual development)

It can only be used in loops

Role: To end this cycle early and continue the preparation for the next cycle (e.g., conditional judgment)

The idea of shortcuts

Error message: Alt + Enter

Quickly copy down a line: CTRL + D

Delete a row (select row) :

CTRL + X (Cut)

CTRL + y (Delete)

To pop up the search box: Double-click Shift

Switch two lines of code: CTRL + Shift +↑/↓

Note:

Single-line comment: CTRL + /

Multi-line comments: CTRL + Shift +/

(Press Cancel again)

Quick formatting: CTRL + Alt + L

Automatically declare variables: CTRL + Alt + V

Rename variables, methods, etc:

​ shift + F6

Rename a class:

​ alt + enter

Or click refactor->rename on the. Java file

Capitalization of whole words:

​ ctrl + shift + U

Shortcut template for code:

  1. The main or PSVM

    public static void main(String[] args) {}
Copy the code

  2. sout

    System.out.println();
Copy the code

  3. fori

    for (int i = 0; i < ; i++) {
            
        }
Copy the code

  4. Customize shortcut templates

    Editor – > Postfix Completion;

    Editor -> Live Template (define -> Java application in Java) custom templates

    Debug: code debugging

    I have a bug.

    Single step debugging:

    1. Set the breakpoint

      Breakpoint: The program stops at a breakpoint

    2. Run, select Debug to run

    3. Select the corresponding button

Step Over: Run this line (F8)

Step Into: Goes Into the called method

(The red one is generally used for source code, force-entry; Usually debug your code in blue.)

Step out: Step out from the trace method (shift + F8)

Resume Program: From previous breakpoint to next breakpoint (F9)

Stop “Class name” : stop debugging

Cancel all breakpoints: the red dot has a slash