java之day5

Posted 2020-10-03 哈喽杏红

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温故

package day5;

import java.util.Scanner;

public class Score {
    //构造函数（不管写不写，都有这个函数，隐藏着）
    public Score(){
        System.out.println("实例化对象调用了我");
    }
    int sum;//和
    double avg;//平均分
    
    //一个方法只能return一个值
    //求和的方法    下面int是返回值的类型
    public int sum(){
        Scanner scanner = new Scanner(System.in);
        for (int i = 0; i < 3; i++) {
            System.out.println("请输入第"+(i+1)+"个学员成绩");
            int score = scanner.nextInt();
            sum += score;
        }
        return sum;
    }
    //求平均分的方法
    public double avg(){
        //int result = sum();
        //return (double)result/3    OR
        Scanner scanner = new Scanner(System.in);
        for (int i = 0; i < 3; i++) {
            System.out.println("请输入第"+(i+1)+"个学员成绩");
            int score = scanner.nextInt();
            sum += score;
        }
        return (double)sum/3;
    }
    //求和和平均分 用数组
    public double[] getAvgAndSum(){
        double [] results = new double[2];
        Scanner scanner = new Scanner(System.in);
        for (int i = 0; i < 3; i++) {
            System.out.println("请输入第"+(i+1)+"个学员成绩");
            int score = scanner.nextInt();
            sum += score;
        }
        results[0] = sum;
        results[1] = sum/3;
        return results;
    }
}

package day5;


public class ScoreCalc {

    public static void main(String[] args) {
        //由类来产生对象（实例化），会调用构造函数
        Score score1 = new Score();
        //对象生成以后，可以调用对象里的各个属性和方法
        
        int sum = score1.sum();
        System.out.println(sum);
        double avg = score1.avg();
        System.out.println(avg);
        
        double[] sum1 = score1.getAvgAndSum();
        System.out.println(sum1[0]);
        System.out.println(sum1[1]);
        
    }

}

==============================================================================================================

package day51;

public class Score {
    //属性
    int math;
    int chinese;
    int english;
    int sum;
    double avg;
    
    //构造函数    与类同名，没有返回值，作用：数据的初始化
    //与test页面中的实例化对象同时数据初始化相对应
    public Score(int math,int chinese,int english){
        this.math = math;
        this.chinese = chinese;
        this.english = english;
    }
    
    //方法
    //求和
    public int sum(){
        sum = math + chinese + english;
        return sum;
    }
    //求平均分
    public double avg(){
        avg = (math + chinese + english)/3.0;
        return avg;
    }
    
}

package day51;

import java.util.Scanner;

public class ScoreTest {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("请输入数学成绩");
        int math = in.nextInt();
        System.out.println("请输入语文成绩");
        int chinese = in.nextInt();
        System.out.println("请输入英语成绩");
        int english = in.nextInt();
        
//        int sum = math +chinese +english;
//        System.out.println("总成绩为"+sum);
//        System.out.println("平均成绩"+sum/3.0);
//        OR下面所有
        
        //单纯的实例化对象
//        Score score = new Score();
//        score.math = math;
//        score.chinese = chinese;
//        score.english = english;
//        OR可以传参简便化，即下面这一行代码
        
        //实例化对象的同时进行数据的初始化
        Score score = new Score(math, chinese, english);
        
        double result1 = score.avg();
        double result2 = score.sum();
        System.out.println("平均成绩为"+result1);
        System.out.println("总成绩为"+result2);
    }
}

==================================================================================================================

package day52;

import java.util.Arrays;
import java.util.Scanner;

public class shuzu {
    //2：把方法封装进类
    public String[] one(String[] name){
        Arrays.sort(name);
        return name;
    }
}

package day52;

import java.io.FilePermission;
import java.io.StringBufferInputStream;
import java.util.Arrays;
import java.util.Scanner;

public class shuzuTest{
    public static void main(String[] args) {
        //1:准备数据
        System.out.println("请输入5个数");
        String[]name = new String[5];
        Scanner in = new Scanner(System.in);
        for (int i = 0; i < 5; i++) {
            name[i] = in.next();
        }
        //3：调用类的方法（先实例化出对象）
        shuzu one = new shuzu();
        String[] two = one.one(name);
        for (int i = 0; i < 5; i++) {
            System.out.print(two[i]+"  ");
        }
        //OR    整成字符串
        //System.out.println(Arrays.toString(two));
    }
}

=================================================================================================================

传对象

package day53;

public class Score {
    int math;
    int chinese;
    int english;
}

package day53;

public class Sum {
    //传对象
    public int sum(Score a){
        return (a.math+a.chinese+a.english);
    }
}

package day53;

import java.util.Scanner;

public class Test {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        Score fen = new Score();
        System.out.println("请输入数学成绩");
        fen.math = in.nextInt();
        System.out.println("请输入语文成绩");
        fen.chinese = in.nextInt();
        System.out.println("请输入英语成绩");
        fen.english = in.nextInt();
        
        Sum he = new Sum();
        int sum1 = he.sum(fen);
        System.out.println(sum1);
    }
    
}

======================================================================================================================

package day54;

public class Student {
    String name;
    int age;
    double height;
}

package day54;

public class StudentManager {
    public double heightAvg(Student[] H){
        double sum = 0;
        for (int i = 0;i<5;i++){
            sum = sum + H[i].height;
        }
        return sum/5;
    }
}

package day54;

import java.util.Scanner;

public class StudentTest {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        Student[] stu = new Student[5];
        for (int i = 0; i < 5; i++) {
            System.out.println("输入"+(i+1)+"个身高");
            stu[i] = new Student();
            stu[i].height = in.nextDouble();
        }
        
        StudentManager stum = new StudentManager();
        double avg = stum.heightAvg(stu);
        System.out.println(avg);
    }
}

===============================================================================================================

package day55;

public class User {
    String name;
    String pwd;
    String sex;
    int age;
    String resignDate;
    String degree;
    public  User() {
        
    }
    public User(String name,String pwd,String sex,int age,String resignDate,String degree){
        this.name = name;
        this.pwd = pwd;
        this.sex = sex;
        this.age = age;
        this.resignDate = resignDate;
        this.degree = degree;
    }
    
    public void showMessage(){
        System.out.println("大家好！我是"+name+"，今年"+age+"岁");
        System.out.println("我是"+resignDate+"注册的，目前的等级是："+degree);
    }
}

package day55;

import java.util.Scanner;

public class UserTest {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        User user = new User();
        System.out.println("请输入你的昵称");
        user.name = scanner.next();
        System.out.println("请输入你的密码");
        user.pwd = scanner.next();
        System.out.println("请输入你的性别");
        user.sex = scanner.next();
        System.out.println("请输入你的年龄");
        user.age = scanner.nextInt();
        System.out.println("请输入你的注册时间");
        user.resignDate = scanner.next();
        System.out.println("请输入你的等级");
        user.degree = scanner.next();
        user.showMessage();
    }
}

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