What does val mean in java

The val keyword in Java is used to declare immutable local variables, that is, their value cannot be changed once assigned. Features are: Immutability: Once initialized, the val variable cannot be reassigned. Local scope: val variables are only visible within the block of code in which they are declared. Type inference: The Java compiler will infer the type of the val variable based on the assigned expression. Local variables only: val can only be used to declare local variables, not class fields or method parameters.

val in Java

In Java, the val keyword is used for declaration Immutable local variables. This means that once a value is assigned to a val variable, its value cannot be changed.

Features

• Immutability: Once initialized, the val variable cannot be reassigned.
• Local scope: val variables are only visible within the code block in which they are declared.
• Type inference: The Java compiler will infer the type of the val variable based on the assigned expression.
• Local variables only: val can only be used to declare local variables, not class fields or method parameters.

Usage

The val keyword is similar to the final keyword, but applies to local variables. The syntax is as follows:

val variableName = expression;

Where:

• variableName is the name of the val variable.
• expression is the expression to be assigned.

Benefits

The benefits of using the val keyword include:

• Enhanced code security: Prevents accidental modification of variables, thereby reducing the risk of errors.
• Improve readability: Explicitly indicates that variables are immutable, making the code easier to understand.
• Avoid concurrency issues: In a multi-threaded environment, the val variable provides thread-safe access to immutable variables.

Example

public class Example {
    public static void main(String[] args) {
        val number = 10;
        // 以下代码将导致编译错误，因为 number 不可变
        // number = 20;
    }
}

In the above example, the val variable number is initialized to 10 and its value cannot be changed.

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