static final String 初始化值

The static final keyword is used to declare a constant variable in Java. When a variable is declared as static final, it means that the variable cannot be changed once it is assigned a value. The value of a static final variable is initialized only once, either at the time of declaration or in a static initializer block.

The initialization value of a static final variable can be any valid constant expression in Java. For example, it can be a literal value (e.g., 10, "hello"), or a result of a calculation (e.g., 2 + 3). It can also be a reference to an object, as long as the object is immutable.

Here is an example of declaring and initializing a static final variable:

public class MyClass {
    public static final int MAX_VALUE = 100;
    public static final String DEFAULT_NAME = "John Doe";
}

In this example, the MAX_VALUE variable is assigned the value 100, and the DEFAULT_NAME variable is assigned the value "John Doe". These values cannot be changed throughout the execution of the program.

It's important to note that the initialization of a static final variable can also be done inside a static initializer block, which is a block of code enclosed in curly braces and preceded by the static keyword. This allows for more complex initialization logic if needed.

public class MyClass {
    public static final int MAX_VALUE;
    
    static {
        // Some complex initialization logic
        MAX_VALUE = calculateMaxValue();
    }
    
    private static int calculateMaxValue() {
        // Complex calculation logic
        return 100;
    }
}

In this example, the MAX_VALUE variable is initialized inside a static initializer block using a custom method calculateMaxValue(). This method can perform complex calculations to determine the value of MAX_VALUE before it is assigned.

Overall, the initialization value of a static final variable can be any valid constant expression, and it cannot be changed once assigned