Common ways to set Java enumeration type values

Common methods for setting values ​​of Java enumeration types

Java enumeration type (enum) is a special class type used for Represents a fixed and finite set of values. Each value of an enumeration type is a constant and can only take on those values ​​specified when the enumeration type is defined.

Common methods for enumeration types to explicitly set values ​​are:

1. Direct assignment

public enum Color {
    RED,
    GREEN,
    BLUE
}

Color color = Color.RED;

This method It is the simplest, directly assigning the constant of the enumeration type to the variable.

2. Using constructors

public enum Color {
    RED(255, 0, 0),
    GREEN(0, 255, 0),
    BLUE(0, 0, 255);

    private int red;
    private int green;
    private int blue;

    private Color(int red, int green, int blue) {
        this.red = red;
        this.green = green;
        this.blue = blue;
    }
}

Color color = new Color(255, 0, 0);

This approach allows you to specify additional information when creating the enumeration value. For example, in the code above, each color value contains its red, green, and blue components.

3. Use the valueOf() method

public enum Color {
    RED,
    GREEN,
    BLUE
}

Color color = Color.valueOf("RED");

This method allows you to use strings to create enumeration values. This is useful when you need to parse an enumeration value from a string.

4. Use the ordinal() method

public enum Color {
    RED,
    GREEN,
    BLUE
}

Color color = Color.RED;
int ordinal = color.ordinal();

This method returns the order of the enumeration value in the enumeration type. This is useful when you need to compare enumeration values.

5. Use compareTo() method

public enum Color {
    RED,
    GREEN,
    BLUE
}

Color color1 = Color.RED;
Color color2 = Color.GREEN;
int comparison = color1.compareTo(color2);

This method compares the size of two enumeration values. If the first enumeration value is greater than the second enumeration value, a positive number is returned; if the first enumeration value is less than the second enumeration value, a negative number is returned; if the two enumeration values ​​are equal, then Return 0.

Other common methods of enumeration types

In addition to the above methods, enumeration types also provide many other common methods, including:

• name() The method returns the name of the enumeration value.
• toString() method returns the string representation of the enumeration value.
• equals() method compares two enumeration values ​​for equality.
• hashCode() The method returns the hash code of the enumeration value.

These methods are very useful in daily use of enumeration types.

Usage scenarios of enumeration types

Enumeration types have many usage scenarios in Java, including:

• Represents a fixed set of And limited values, such as color, gender, status, etc.
• Control the flow of the program, such as state machine, menu, etc.
• As a data structure, such as collections, mappings, etc.
• As parameter type or return value type to improve the readability and maintainability of the code.

Enumeration types are a very useful tool that can help you write more robust and readable code.

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