control statement

[Mandatory] In a switch block, each case is either terminated by break/return, etc., or a comment indicates which case the program will continue to execute; in a switch block, a default statement must be included and placed at the end , even with empty code.
[Mandatory] Braces must be used in if/else/for/while/do statements. Even if there is only one line of code, avoid single-line coding:if (condition) statements;
[Mandatory] In high concurrency scenarios, avoid using "equals" as a condition for mid or exit.
- Note: If the concurrency control is not handled properly, the "breakdown" condition is replaced by the greater or lesser interval judgment condition.
- Counter example: When it is judged that the number of remaining prizes is equal to 0, the distribution of prizes will be terminated, but due to a parallel processing error, the number will instantly become a negative number, so the event cannot be terminated.

[Recommended] When expressing abnormal branches, use the if-else method less.

Recommended way:

if (condition) {
    ...
    return obj;
}
// 接着写else的业务逻辑代码;

Note: If you have to use if()…else if()…else… to express logic, [mandatory] To avoid the difficulty of subsequent code maintenance, please do not exceed 3 layers.

Positive example: The logic judgment code of if-else with more than 3 layers can be implemented by using guard statements, strategy patterns, state patterns, etc. The examples of guard statements are as follows:

public void today() {
    if (isBusy()) {
        System.out.println(“change time.”);
        return;
    }
    if (isFree()) {
        System.out.println(“go to travel.”);
        return;
    }
    // 也是皮，只有不忙不闲的时候来学习
    System.out.println(“stay at home to learn Alibaba Java Coding Guidelines.”);
    return;
}

[Recommended] In addition to common methods (such as getXxx/isXxx), do not execute other complex statements in conditional judgments, and assign the result of complex logical judgments to a meaningful Boolean variable name to improve readability.

Java Coding Standard 7 (Programming Specifications - Control Statements)

control statement

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