Use java's Scanner.hasNextLine() function to determine whether there is another line of input

Use java's Scanner.hasNextLine() function to determine whether there is another line of input

In Java programming, we often need to read input from users or files. The Scanner class is a commonly used input class in Java, and it provides many convenient methods to read input. Among them, the Scanner.hasNextLine() function is a very important method, which can be used to determine whether there is another line of input. Next we will introduce the usage of this function in detail and attach corresponding code examples.

Scanner.hasNextLine() function is a method of the Scanner class, used to check whether there is the next line of data in the input source. This function returns a Boolean value, true means there is still the next line of input, false means there is no next line of input. In practical applications, we can use this function to design the input process to ensure that we do not perform read operations when there is no input.

The following is a sample code using the Scanner.hasNextLine() function:

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        // 创建Scanner对象，用于读取输入
        Scanner scanner = new Scanner(System.in);

        System.out.println("请输入一些内容，以空行结束：");
        
        // 使用Scanner.hasNextLine()函数判断是否还有下一行输入
        while (scanner.hasNextLine()) {
            // 读取下一行输入
            String line = scanner.nextLine();
            
            // 如果读取到的是空行，则结束循环
            if (line.equals("")) {
                break;
            }
            
            // 处理读取到的输入数据
            System.out.println("你输入的内容是：" + line);
        }
        
        // 关闭Scanner对象
        scanner.close();
    }
}

In the above sample code, we first create a Scanner object for reading input. Then, by using the Scanner.hasNextLine() function, we can continuously read the next line of input in the loop. When we enter a blank line, the program will exit the loop and end the input process.

The advantage of using the Scanner.hasNextLine() function is that it can avoid reading operations when there is no input and prevent exception errors in the program. At the same time, using this function can easily design the input process, allowing us to fully control the timing of input.

In summary, the Scanner.hasNextLine() function is an important method in Java to determine whether there is another line of input. We can use it when we need to read input. By judging whether there is another line of input, we can reasonably control the input process and improve the robustness and user-friendliness of the program. I hope this article can help you understand and use the Scanner.hasNextLine() function.

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