How do Java enum types work with switch statements?

The enumeration type is a data type that defines a collection of constants in Java. Together with the switch statement, the following functions can be achieved: Clearly represent the value range: The enumeration type is used to define a set of immutable constant values ​​to improve code readability. Matching different enumeration constants: The switch statement allows different operations to be performed based on the enumeration constants to achieve refined control. Handle different scenarios: Through enumeration types and switch statements, various situations can be flexibly handled in actual scenarios, such as different notification types sending different email contents.

The use of Java enumeration types with switch statements

The enumeration type is a very useful data type in Java, which can define a set of constant. When used with switch statements, enumeration types can make code clearer, readable, and maintainable.

Using enumeration types

To use enumeration types, you need to create an enumeration class using the enum keyword. For example:

public enum Color {
    RED,
    GREEN,
    BLUE
}

This enumeration class defines three constants: RED, GREEN, and BLUE.

Use switch statement

The switch statement can perform different operations based on enumeration constants. The syntax is as follows:

switch (enumValue) {
    case CONSTANT1:
        // 按常量1执行的操作
        break;
    case CONSTANT2:
        // 按常量2执行的操作
        break;
    default:
        // 默认情况下执行的操作
        break;
}

For example, we can use the switch statement to print different messages based on color enumeration:

Color color = Color.RED;

switch (color) {
    case RED:
        System.out.println("颜色是红色");
        break;
    case GREEN:
        System.out.println("颜色是绿色");
        break;
    case BLUE:
        System.out.println("颜色是蓝色");
        break;
    default:
        System.out.println("无效颜色");
}

Practical case

Mailbox notification system

In an email notification system, we need to send different types of notifications to users. We can use enumeration types to define notification types, and use switch statements to send corresponding email content according to notification types:

public enum NotificationType {
    WELCOME,
    PASSWORD_RESET,
    ORDER_STATUS
}

// 发送邮件的方法
public void sendEmail(NotificationType notificationType) {
    switch (notificationType) {
        case WELCOME:
            // 发送欢迎邮件
            break;
        case PASSWORD_RESET:
            // 发送密码重置邮件
            break;
        case ORDER_STATUS:
            // 发送订单状态邮件
            break;
        default:
            // 处理无效通知类型
            break;
    }
}

// 使用示例
NotificationType notificationType = NotificationType.WELCOME;
sendEmail(notificationType);

By using enumeration types and switch statements, we can easily handle different types of notifications, and Provide customized email content.

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