In Java programming, how to stop subsequent code execution when student ID is repeated?

Java programs: Avoid student ID duplication and optimize code execution

This article discusses how to effectively deal with the problem of duplicate IDs when entering student information in Java programs, and avoid repeated input of other information.

Problem: After the existing code detects duplication of student ID, it will continue to perform subsequent name, age, and address entry processes.

Improvement: By improving data structure and code logic, stop subsequent operations immediately when ID duplication is detected.

Solution:

HashMap is used to store student information and use student ID as key to achieve efficient ID repetitive checks. The modified code is as follows:

 import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class StudentManager {

    private static Map<string student> studentMap = new HashMap();

    public static int addStudent() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Please enter student ID:");
        String studentId = scanner.next();

        if (studentMap.containsKey(studentId)) {
            System.out.println("Student ID already exists, failed to add!");
            return 0; // ID is repeated, return immediately}

        Student student = new Student();
        student.setId(studentId);
        System.out.print("Please enter the student name:");
        student.setName(scanner.next());
        System.out.print("Please enter the student's age:");
        student.setAge(scanner.nextInt());
        System.out.print("Please enter the student address:");
        student.setAddress(scanner.next());

        studentMap.put(studentId, student);
        System.out.println("Student information was added successfully!");
        return 1;
    }


    public static class Student {
        private String id;
        private String name;
        private int age;
        private String address;

        //getter and setter methods
        public String getId() { return id; }
        public void setId(String id) { this.id = id; }
        public String getName() { return name; }
        public void setName(String name) { this.name = name; }
        public int getAge() { return age; }
        public void setAge(int age) { this.age = age; }
        public String getAddress() { return address; }
        public void setAddress(String address) { this.address = address; }
    }

    public static void main(String[] args) {
        addStudent();
    }
}</string>

Code explanation:

1. Use HashMap: studentMap to store student information using HashMap , the key is the student ID, and the value is Student object. HashMap provides containsKey() method, which can quickly and efficiently check whether the ID exists.

2. Check the ID in advance: Before entering other information, use studentMap.containsKey(studentId) to check whether the ID already exists. If it exists, print the error message and return immediately, stopping subsequent operations.

3. Static variable: studentMap is declared as a static variable, ensuring that data can be retained when addStudent() method is called multiple times.

With these improvements, the program can stop immediately when the ID is detected, avoiding unnecessary input operations and improving code efficiency and user experience.

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