Java入门基础之习题集

练习一

package day4;

import java.util.Scanner;

public class First {
public void show(){
System.out.println("\t欢迎使用我行我素购物管理系统");
System.out.println("\t1.登录管理系统");
System.out.println("\t2.退出");
System.out.println("**********************************");
System.out.print("请选择，输入数字：");
System.out.println();
Scanner input = new Scanner(System.in);
int a = input.nextInt();
if(a==1){
Second i= new Second();
i.show();
}
}
public static void main(String[] args) {
First a = new First();
a.show();
}
}

package day4;

import java.util.Scanner;

public class Second {
public void show(){
System.out.println("\t欢迎使用我行我素购物主菜单");
System.out.println("\t\t1.客户管理系统");
System.out.println("\t\t2.真情回馈");
System.out.println("**********************************");
System.out.print("请选择，输入数字或者按0返回上一级菜单：");
System.out.println();
Scanner input = new Scanner(System.in);
int b = input.nextInt();
if(b==0){
First j = new First();
j.show();
}
else if(b==2){
Third k = new Third();
k.show();
}
}

}

package day4;

import java.util.Scanner;

public class Third {
public void show(){
System.out.println("\t欢迎使用我行我素购物购物管理系统>真情回馈");
System.out.println("\t\t1.幸运大抽奖");
System.out.println("\t\t2.幸运抽奖");
System.out.println("**************************************");
System.out.print("请选择，输入数字或者按0返回上一级菜单：");
System.out.println();
Scanner input = new Scanner(System.in);
int b = input.nextInt();
if(b==0){
Second j = new Second();
j.show();
}
}

}

练习二

package Day5;

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

package Day5;

public class Second {
public double avg(First []a){
double sum = 0;
for (int i = 0; i < 5; i++) {
sum=sum+a[i].height;
}
return sum/5;
}
}

package Day5;

import java.util.Scanner;

public class Third {

public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner input = new Scanner(System.in);
First stu[] = new First[5];
for (int i = 0; i < 5; i++) {
System.out.println("请输入第"+(i+1)+"名学生的身高（cm）：");
stu[i] = new First();
stu[i].height = input.nextDouble();
}
Second aSecond = new Second();
double avg = aSecond.avg(stu);
System.out.println("***这五名学生的平均身高为："+avg+"cm***");
}

}

练习三

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));
}
}

练习四

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();
}
}