How to use Pattern Matching for type matching and destructuring in Java 14

How to use Pattern Matching for type matching and destructuring in Java 14

Introduction:
In Java 14, an important new feature is introduced, namely Pattern Matching. Pattern Matching allows developers to perform type matching and destructuring operations in conditional statements, thereby simplifying code writing and reading. This article will introduce how to use Pattern Matching for type matching and destructuring in Java 14, and illustrate it with code examples.

1. Type matching
In previous Java versions, we often needed to use the instanceof operator to determine whether an object belongs to a specific type, and then perform corresponding operations. In Java 14, the introduction of Pattern Matching makes type matching more concise and intuitive.

The sample code is as follows:

public static void process(Object obj) {
    if (obj instanceof String s) {
        System.out.println("对象是一个字符串：" + s);
        // 在此可以直接使用s进行相关操作
    } else if (obj instanceof Integer i) {
        System.out.println("对象是一个整数：" + i);
        // 在此可以直接使用i进行相关操作
    } else {
        System.out.println("对象不是字符串也不是整数！");
    }
}

In the above example, we use the syntax that combines the instanceof operator and Pattern Matching, that is, converting the object to the corresponding type and assigning a value while judging the type. Give a new variable s or i. In this way, we can directly use the new variables in the conditional statement to perform related operations, avoiding the trouble of type conversion again.

2. Application of destructuring
In addition to type matching, Pattern Matching also supports destructuring operations on objects, that is, decomposing the field values ​​​​of the object into multiple variables for more convenient operations.

The sample code is as follows:

record Point(int x, int y) {}

public static void destructurePoint(Point p) {
    if (p instanceof Point(x, y)) { // 构造解构
        System.out.println("点的坐标是：" + x + ", " + y);
    }
}

In the above example, we defined a Point class and used the new record keyword in Java 14 to define an immutable data class. Then, in the destructurePoint method, we use the syntax of the instanceof operator and Pattern Matching to decompose the field value of the p object into two variables x and y. In this way, we can directly use x and y to perform related operations without Field values ​​need to be obtained through ordinary getter methods.

Summary:
Through the above introduction and sample code, we can see that in Java 14, the introduction of Pattern Matching provides us with a more concise and intuitive way to perform type matching. and deconstruction operations. It not only greatly simplifies the writing and reading of code, but also improves the readability and maintainability of code. Therefore, in development, we should make full use of the function of Pattern Matching to improve the quality and efficiency of the code.

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