第二本书 二章（课后题）

package com.opp.homework2.demo1;

public class Demo1 {
    public void seasons(int num) {


        if (num == 2 || num == 3 || num == 4) {

            System.out.println("春季");
 }
        if (num == 5 || num == 6 || num == 7) {

            System.out.println("夏季");
 }
        if (num == 8 || num == 9 || num == 10) {

            System.out.println("秋季");
 }
        if (num == 12 || num == 11 || num == 1) {

            System.out.println("冬季");
 }
    }
}

package com.opp.homework2.demo1;

import java.util.Scanner;

public class MyMain {
    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
 System.out.println("请输入月份：");
        int number=scanner.nextInt();
 Demo1 demo1 =new Demo1();
 demo1.seasons(number);

 }
}

package com.opp.homework2.demo2;

public class MyMain {
    public static void main(String[] args) {
            QuessMachine qm=new QuessMachine();
qm.initial();
qm.guess();

}
}

package com.opp.homework2.demo2;

import java.util.Scanner;

public class QuessMachine {


    int num,guessNum;

    public void initial(){
        num=(int)(Math.random()*100);
 System.out.println(num);
 }
    public void guess(){
        Scanner scanner=new Scanner(System.in);
        boolean flag=false;
        do {
            System.out.println("请输入您的猜测价格：");
 guessNum = scanner.nextInt();
            if (guessNum > num) {
                System.out.println("再小些");
 } else if (guessNum < num) {
                System.out.println("再大些");
 } else {
                System.out.println("猜对了");
 flag=true;
 }
        }while (!flag);
 }
}

package com.opp.homework2.demo3;

import java.util.Arrays;

public class Demo3 {
    public void insertArray(int[] arr, int index, int value) {
        int[] newArr = Arrays.copyOf(arr, 8);
        for (int i = newArr.length - 1; i > index; i--) {
            newArr[i] = newArr[i - 1];
 }
        newArr[index] = value;
        for (int a : newArr) {
            System.out.println(a);
 }
    }
}

/*未想完

package com.opp.homework2.demo3;

import java.util.Scanner;

public class MyMain {
    public static void main(String[] args) {
        Demo3 demo3 = new Demo3();
        int[] arr = {3, 64, 15, 36, 72, 38, 29};
        for (int b:arr) {
            System.out.println(b);
 }
        Scanner scanner = new Scanner(System.in);
 System.out.println("请输入要插入的位置：");
        int index = scanner.nextInt();
 System.out.println("请输入要插入的数字：");
        int value = scanner.nextInt();
 demo3.insertArray(arr, index, value);
 }
}

*/

package com.opp.homework2;

import java.util.Scanner;

public class MyMain {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (in.hasNextInt()) {
            int n = in.nextInt();
            int m = in.nextInt();

 Student[] stu = new Student[n];  //创建n个学生对象的数组
 double[] avg = new double[m];    //各科的平均成绩
 int i, j;
            int sum, num = 0;

            for (i = 0; i < n; i++) {
                sum = 0;
 stu[i] = new Student(m);
                for (j = 0; j < m; j++) {    //依次读入一个学生的各科成绩
 stu[i].grade[j] = in.nextInt();
 sum += stu[i].grade[j];             //一个学生实例的成绩总和
 avg[j] += stu[i].grade[j];          //各科的总成绩
 }
                stu[i].setAvg(sum * 1.0 / m);   //设置该学生的平均成绩
 }
            for (j = 0; j < m; j++) {   //各科的总成绩取平均
 avg[j] /= n;
 }

            boolean flag;
 //计算各科成绩均大于等于平均成绩的学生数量
 for (i = 0; i < n; i++) {
                flag = true;
                for (j = 0; j < m; j++) {
                    if (stu[i].grade[j] < avg[j]) {
                        flag = false;
                        break;
 }
                }
                
 if (flag) {
                    num++;
 }
            }

            
 for (i = 0; i < n - 1; i++) {
                System.out.printf("%.2f ", stu[i].avg);
 }
            System.out.printf("%.2f", stu[n - 1].avg);
 System.out.println();
            for (i = 0; i < m - 1; i++) {
                System.out.printf("%.2f ", avg[i]);
 }
            System.out.printf("%.2f", avg[m - 1]);
 System.out.println();
 System.out.println(num);
 System.out.println();
 }

    }

    public static class Student {
        double avg;
        double[] grade;

 //Student类的构造函数
 public Student(int m) {
            grade = new double[m];  //实例化每个Student的成绩数组
 }

        public void setAvg(double avg) {
            this.avg = avg;
 }
    }

}

package com.opp.unit2.homework2.demo4;

import java.util.Scanner;

public class MyMain {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String chioce;
        StudentBiz studentBiz = new StudentBiz();

        do {
            /**
             * 写入数值，带入数组
             */
            Student student = new Student();
            System.out.println("请输入学号：");
            student.id=scanner.nextInt();
            System.out.println("请输入JAVA成绩：");
            student.javaScores = scanner.nextDouble();
            System.out.println("请输入C3成绩：");
            student.CScores = scanner.nextDouble();
            System.out.println("请输入DB成绩：");
            student.dbScores = scanner.nextDouble();
            studentBiz.addScores(student);
            System.out.println("是否继续？(y/n)");
            chioce = scanner.next();
        } while ("y".equals(chioce));
        studentBiz.showavgs();
    }
}

package com.opp.unit2.homework2.demo4;

public class Student {
    /**
     * 定义学生属性
     */

    public double javaScores;
    public double CScores;
    public double dbScores;
    public double avg;
    public int id;

    /**
     * 定义显示学生方法
     */
    public void showInfo() {
        System.out.println("学生"+id+"平均成绩为:" + (avg = (javaScores + CScores + dbScores) / 3));
    }
}

package com.opp.unit2.homework2.demo4;


public class StudentBiz {
    /**
     * 学生管理类
     */
    Student[] avgs = new Student[10];

    /**
     * 添加学生信息（成绩）
     *
     * @param avg
     * @date 将学生数据作为元素存入数组（变成参数插入）
     */
    public void addScores(Student avg) {
        for (int i = 0; i < avgs.length; i++) {
            if (avgs[i] == null) {
                avgs[i] = avg;
                break;
            }
        }
    }

    /**
     * 展示每个学生的3科平均分
     */
    public void showavgs() {
        System.out.println("学生平均分为：");
        for (int i = 0; i < avgs.length; i++) {
            if (avgs[i] != null) {
                avgs[i].showInfo();
            }
        }
    }


}