java read data from console

Java uses the java.util.Scanner class to read input from the console: read data from the console by creating a Scanner object and passing it into System.in (standard input stream):

// 从控制台读取一个字符串和一个整数的例子
import java.util.Scanner;

public class Main {
    
    
    public static void main(String[] args) {
    
    
        Scanner scanner = new Scanner(System.in); // 创建Scanner对象
        System.out.print("Input your name: "); // 打印提示
        String name = scanner.nextLine(); // 读取一行输入并获取字符串
        System.out.print("Input your age: "); // 打印提示
        int age = scanner.nextInt(); // 读取一行输入并获取整数
        System.out.printf("Hi, %s, you are %d\n", name, age); // 格式化输出
    }
}

operation result:

This type of input method is often used in written examination questions. Here is a simple example: design a program to input the scores of the last exam and the scores of this exam, and then output the percentage of score improvement, retaining two decimal places (for example, 10.55% ).

public class scanner {
    
    
    public static void main(String[] args) {
    
    
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter your last test score:");
        float lastScore = scanner.nextFloat();
        if (lastScore == 0){
    
    
            System.out.println("The last test score cannot be 0");
            return;
        }
        System.out.print("Enter your score for this test:");
        float thisScore = scanner.nextFloat();
        float improvementPercentage = (thisScore - lastScore) / lastScore;
        System.out.printf("The percentage of improvement in grades = %.2f%%",improvementPercentage * 100);
    }
}

operation result: