Interpretation of Java documentation: Usage analysis of hasNext() method of Scanner class

The Scanner class is a commonly used input class in Java. It can read input from the console or file. There are many useful methods in the Scanner class, among which the hasNext() method is one of the commonly used methods.

The hasNext() method is a Boolean method in the Scanner class, used to determine whether there is another input item in the input stream. If there is another input item in the input stream, this method returns true, otherwise it returns false. Its syntax structure is as follows:

public boolean hasNext()

hasNext() method is mainly used to detect input and avoid abnormal conditions. When using Scanner for input, we need to continuously detect the input. If you simply read the input, such as using the next() method, the program will throw a NoSuchElementException when the input ends. Therefore, before reading, we need to check whether there is any input to avoid abnormal termination of the program.

The following is a specific code example using the hasNext() method:

import java.util.Scanner; public class Main { public static void main(String[] args) { // 创建一个 Scanner 对象 Scanner scanner = new Scanner(System.in); // 持续读取输入 while (scanner.hasNext()) { // 读取当前输入 String input = scanner.next(); // 输出读取的内容 System.out.println(input); } // 关闭 Scanner 对象 scanner.close(); } }

In the above code, we use the Scanner class to read the user's input and continuously read the input through the while loop . In each loop, we first use the hasNext() method to detect whether there is another input item in the input stream. If so, we then use the next() method to read the input and output its content. The loop ends when there is no more input.

In short, the hasNext() method is one of the most commonly used methods in the Scanner class. It is detected when reading input, which can effectively avoid exceptions in the program when there is no input. Therefore, when using the Scanner class, we need to keep in mind the importance of using the hasNext() method.

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