4.21

构造方法vs普通方法

构造方法

import java.util.Scanner;
public class Main
{
    public static void main(String[] args)
    {
        Scanner in=new Scanner(System.in);
        Student std;
        String name=in.next();
        int age=in.nextInt();
        String sex=in.next();
        std=new Student(name,sex,age);//构造方法的好处，创建对象同时自动赋值
        System.out.println(std);
    }
}
class Student
{
    private String name;
    private String sex;
    private int age;
    public Student(String name,String sex,int age)//1.方法名和类名必须相同2.无返回值
    {
        this.name=name;
        this.sex=sex;
        this.age=age;
    }
    public String toString()
    {
        return "Student [name='"+name+"', sex='"+sex+"', age="+age+"]";
    }
}

数组类

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        Team[] teams = new Team[5];
        for (int i = 0; i < 5; i++) {
            teams[i] = new Team(); // 创建对象

            teams[i].setTeamId(i + 1); // 编号1~5

            String intro = scanner.nextLine(); // 输入介绍
            teams[i].setIntroduction(intro);
        }

        for (int i = 0; i < 5; i++) {
            System.out.println("参赛队伍" 
                + teams[i].getTeamId() 
                + ": " 
                + teams[i].getIntroduction());
        }

        scanner.close();
    }
}

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        // 1️⃣ 输入数组长度
        int n = sc.nextInt();
        sc.nextLine(); // 吃掉换行

        // 2️⃣ 创建数组
        Person[] arr = new Person[n];

        // 3️⃣ 输入每个人信息
        for (int i = 0; i < n; i++) {
            String name = sc.nextLine();
            int age = sc.nextInt();
            sc.nextLine(); // 吃掉换行

            arr[i] = new Person(name, age);
        }

        // 4️⃣ 输出所有人信息
        for (int i = 0; i < n; i++) {
            System.out.println(arr[i]);
        }

        // 5️⃣ 查询
        String target = sc.nextLine();

        boolean found = false;

        for (int i = 0; i < n; i++) {
            if (arr[i].getName().equals(target)) {
                System.out.println(arr[i]);
                found = true;
                break;
            }
        }

        if (!found) {
            System.out.println("not found");
        }

        sc.close();
    }
}