Java实现学生信息查询方法详解

public class Student {
    private String id;
    private String name;
    private int age;
    private double score;

    public Student(String id, String name, int age, double score) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.score = score;
    }

    // Getter 和 Setter 方法
    public String getId() { return id; }
    public String getName() { return name; }
    public int getAge() { return age; }
    public double getScore() { return score; }

    @Override
    public String toString() {
        return "Student{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", score=" + score +
                '}';
    }
}

import java.util.ArrayList;
import java.util.List;

List<Student> students = new ArrayList<>();
students.add(new Student("001", "张三", 20, 85.5));
students.add(new Student("002", "李四", 19, 92.0));
students.add(new Student("003", "王五", 21, 78.0));

// 按学号查询
public Student findByID(String id) {
    for (Student s : students) {
        if (s.getId().equals(id)) {
            return s;
        }
    }
    return null; // 未找到
}

// 按姓名关键字查询（返回列表）
public List<Student> findByName(String keyword) {
    List<Student> result = new ArrayList<>();
    for (Student s : students) {
        if (s.getName().contains(keyword)) {
            result.add(s);
        }
    }
    return result;
}

// 查询成绩高于某分数的学生
public List<Student> findByScoreAbove(double threshold) {
    return students.stream()
                   .filter(s -> s.getScore() >= threshold)
                   .toList();
}