Java Error: Java12 Switch Expression Error, How to Handle and Avoid

Java 12 Switch expression is a new feature that Java programmers prefer to use. It greatly simplifies the writing of code and also increases the readability of the code. However, regular Switch statements may generate some errors in Java 12, and this article will explain how to handle and avoid these errors.

Switch expression is a new syntax form that is more compact and convenient than the regular Switch statement. The following is a regular Switch statement:

int dayOfWeek = 2;
String day;

switch (dayOfWeek) {
    case 1:
        day = "Monday";
        break;
    case 2:
        day = "Tuesday";
        break;
    case 3:
        day = "Wednesday";
        break;
    case 4:
        day = "Thursday";
        break;
    case 5:
        day = "Friday";
        break;
    default:
        day = "Weekend";
        break;
}

After using the Switch expression, it can be simplified to the following form:

int dayOfWeek = 2;
String day = switch (dayOfWeek) {
    case 1 -> "Monday";
    case 2 -> "Tuesday";
    case 3 -> "Wednesday";
    case 4 -> "Thursday";
    case 5 -> "Friday";
    default -> "Weekend";
};

In Java 12, the Switch expression supports two forms: Lambda form and regular case form. The lambda form usually separates conditions and expressions by arrow symbols (->), while the regular case form uses colons (:) to separate conditions and expressions.

However, the Switch expression may have some errors in Java 12, mainly due to the upgrade of the Switch statement in Java 12, resulting in improper use, lack of necessary syntax elements, or the intention to use it in Java 12. Issues arise when migrating code from earlier versions to Java 12.

Here are some ways to handle and avoid Switch expression errors:

1. Avoid mixing Lambda and regular case forms

Although Switch expressions are supported Lambda form and regular case form, but they cannot be mixed. Using different forms in the same Switch expression may cause compilation errors.

2. Using the Break statement

In the Switch statement, each case statement block must usually end with a break statement. This rule also applies to Switch expressions. However, sometimes we may forget to add a break statement, resulting in compilation errors. To avoid this error, we can use the yield statement instead of the break statement.

3. Using the Default statement

When using a Switch expression, if a default statement is not provided, the compiler will generate a warning. If an unhandled condition occurs in a Switch expression, the program will throw a compilation error.

4. Avoid using complex expressions

In a Switch expression, each condition must be a constant expression. If the expression is too complex, compilation errors may occur. To avoid this error, we should avoid using complex expressions as much as possible and define them as constants whenever possible.

5. Avoid using nested Switch expressions

Although Switch expressions can be used nested like regular Switch statements, in Java 12, nested Switch expressions The expression may cause the compiler to generate errors. To avoid this error, we should avoid using nested Switch expressions whenever possible.

In short, the Switch expression in Java 12 is a very useful new feature that can greatly simplify the work of Java programmers. However, there are some mistakes to avoid when using it so you can get the most out of it. Therefore, programmers should use Switch expressions with caution and follow best practices regarding Switch expressions.

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