【记录】Java 练习题10.18

记录

Java练习题

第三章练习题
共四个练习

1：仿照学生类，编写一个手机类，并测试。

MobilePhone.java

package practice1;

public class MobilePhone {
     
	private final String name;	//只能在三个地方初始化赋值	成员变量被final修饰后没有默认值
	/*{
		this.name = "HuaWei";
	}这个是在程序块赋值*/
	//这里用构造方法赋值
	public MobilePhone(String name) {
     
		this.name = name;
	}
	public final void introduce() {
     
		final String color;		//局部变量没有默认值
		System.out.println("The mobile phone's name is:"+name);
		color = "black";
		System.out.println("The mobile phone's color is:"+color);
	}
}

HuaweiPhone.java

package practice1;

public class HuaweiPhone extends MobilePhone {
     
	public HuaweiPhone(String name) {
     	//子类中会默认调用父类不带参数的构造方法，若父类中没有不带参数的构造方法，则需要显式调用，即此代码
		super(name);	//调用父类中带参数的构造方法
	}/**/
	/*public void introduce() {	//子类不能重写父类中被final修饰过的方法
		
	}*/
}

Test1.java

package practice1;

public class Test1 {
     
	//测试类
	public static void main(String[] args) {
     
		MobilePhone mp1 = new MobilePhone("XiaoMi");
		mp1.introduce();
		HuaweiPhone hp1 = new HuaweiPhone("Huawei");
		hp1.introduce();
		MobilePhone mp2 = new HuaweiPhone("Iphone");	//这就是多态，具体还不知道有什么用法
		mp2.introduce();
	}
}

2：

1.定义一个电视机类，实现电视机的基本功能（换台，调整音量，开关），并测试。

TV.java

package practice2_1;

public class TV {
     
	int channel = 0;
	int volume = 0;
	int tvswitch = 0;
	/*1.定义一个电视机类，实现电视机的基本功能（换台，调整音量，开关），并测试。*/
	//1. Define a TV set, realize the basic functions of the TV set (channel change, 
	//volume adjustment, switch), and test it.
	public void ChannelChange(int channel) {
     
		this.channel = channel;
		System.out.println("现在是"+channel+"台");
	}
	public void VolumeAdjustment(int volumechange) {
     
		if(volumechange == 1) {
     
			if(volume >= 3) {
     
				System.out.println("已经是最大音量!");
				return ;
			}
			this.volume++;
		}
			
		else if(volumechange == 0) {
     
			if(volume <= 0) {
     
				System.out.println("已经是最低音量!");
				return ;
			}
			this.volume--;
		}
			
		else 
			System.out.println("Error!");
		System.out.println("现在音量是"+this.volume);
	}
	public void Switch(int tvswitch) {
     
		if(tvswitch == 1) {
     
			System.out.println("电视打开!");
		}
		else if(tvswitch == 0) {
     
			System.out.println("电视关闭!");
		}
		else 
			System.out.println("Error!");
		this.tvswitch = tvswitch;
	}
}

Test2_1.java

package practice2_1;
import java.util.Scanner;

public class Test2_1 {
     
	public static void main(String[] args) {
     
		TV tv = new TV();
		System.out.println("现在有一台关闭的电视!");
		int select = 1;
		@SuppressWarnings("resource")		//我也不知道是啥。。。不加这个的话inTo会有一个小警告
		Scanner inTo = new Scanner(System.in);
		System.out.println("1.打开电视!");
		System.out.println("0.离开!");
		System.out.println("请选择：");
		select = inTo.nextInt();
		tv.Switch(select);
		if(select == 0) {
     
			System.out.println("已退出!");
			return;
		}
		else {
     
			while(select != 0) {
     
				System.out.println("1.换台!");
				System.out.println("2.调音量!");
				System.out.println("0.关电视!");
				System.out.println("请选择：");
				select = inTo.nextInt();
				switch(select) {
     
					case 1:
						int channel = 0;
						System.out.println("请输入台数：");
						channel = inTo.nextInt();
						tv.ChannelChange(channel);
						break;
					case 2:
						int volume = 0;
						System.out.println("1.增大音量!");
						System.out.println("0.减小音量!");
						volume = inTo.nextInt();
						tv.VolumeAdjustment(volume);
						break;
					case 0:
						tv.Switch(select);
						System.out.println("已退出!");
						break;
				}
			}
		}
	}
}

后来才发现课本上有例题。。。
下面是课本例题代码

TV.java

package practice2_1_again;

public class TV {
     
	int channel;	//电视频道
	void setChanner(int m) {
     
		if(m>1) {
     
			channel = m;
		}
	}
	int getChannel() {
     
		return channel;
	}
	void showProgram() {
     
		switch(channel) {
     
		case 1:
			System.out.println("综合频道");
			break;
		case 2:
			System.out.println("经济频道");
			break;
		case 3:
			System.out.println("文艺频道");
			break;
		case 4:
			System.out.println("国际频道");
			break;
		case 5:
			System.out.println("体育频道");
			break;
		default:
			System.out.println("不能收看"+channel+"频道");
		}
	}
}

Chineses.java

package practice2_1_again;

public class Chineses {
     
	TV homeTV;
	void buyTV(TV tv) {
     
		homeTV = tv;
	}
	void remoteControl(int m) {
     
		homeTV.setChanner(m);
	}
	void seeTV() {
     
		homeTV.showProgram();
		System.out.println("用户买回的电视是在"+homeTV.getChannel()+"频道");
	}
}

Example4_5.java

package practice2_1_again;

public class Example4_5 {
     
	public static void main(String[] args) {
     
		TV haierTV = new TV();
		haierTV.setChanner(5);
		System.out.println("卖给用户的haierTV目前的频道是"+haierTV.getChannel());
		Chineses zhangsan = new Chineses();
		zhangsan.buyTV(haierTV);
		System.out.println("zhangsan开始看电视节目");
		zhangsan.seeTV();
		int m = 2;
		System.out.println("zhangsan用遥控器将买回的电视更改到"+m+"频道");
		zhangsan.remoteControl(m);
		System.out.println("现在卖给用户的haierTV目前的频道是"+haierTV.getChannel());
		System.out.println("zhangsan再看电视节目");
		zhangsan.seeTV();
	}
}

2.设计一个分数类，分数的分子和分母用两个整型数表示，类中定义方法对分数进行加、减、乘、除运算。定义分数类对象，运算并输出运算结果。

Fractions.java

package practice2_2;

public class Fractions {
     
	public int fson;
	public int fmom;
	//求分子分母的最大公约数
	public int gcd(int a,int b) {
     
		if(a < b) {
     
			int c = a;
			a = b;
			b = c;
		}
		int r = a % b;
		while(r != 0) {
     
			a = b;
			b = r;
			r = a % b;
		}
		return b;
	}
	public void fAdd(int fson1,int fmom1,int fson2,int fmom2) {
     
		int fm = fmom1*fmom2;
		fson1 = fson1*fmom2;
		fson2 = fson2*fmom1;
		int fs = fson1+fson2;
		int g = gcd(fs, fm);
		System.out.println("最大公约数："+g);
		fs = fs / g;
		fm = fm / g;
		System.out.println("加法运算后结果中分子为："+fs);
		System.out.println("加法运算后结果中分母为："+fm);
		System.out.println("即分数为："+fs+"/"+fm);
	}
	public void fSub(int fson1,int fmom1,int fson2,int fmom2) {
     
		int fm = fmom1*fmom2;
		fson1 = fson1*fmom2;
		fson2 = fson2*fmom1;
		int fs = fson1-fson2;
		int g = gcd(fs, fm);
		fs = fs / g;
		fm = fm / g;
		System.out.println("减法运算后结果中分子为："+fs);
		System.out.println("减法运算后结果中分母为："+fm);
		System.out.println("即分数为："+fs+"/"+fm);
	}
	public void fMul(int fson1,int fmom1,int fson2,int fmom2) {
     
		int fm = fmom1*fmom2;
		int fs = fson1*fson2;
		int g = gcd(fs, fm);
		fs = fs / g;
		fm = fm / g;
		System.out.println("乘法运算后结果中分子为："+fs);
		System.out.println("乘法运算后结果中分母为："+fm);
		System.out.println("即分数为："+fs+"/"+fm);
	}
	public void fDiv(int fson1,int fmom1,int fson2,int fmom2) {
     
		int fm = fmom1*fson2;
		int fs = fson1*fmom2;
		int g = gcd(fs, fm);
		fs = fs / g;
		fm = fm / g;
		System.out.println("除法运算后结果中分子为："+fs);
		System.out.println("除法运算后结果中分母为："+fm);
		System.out.println("即分数为："+fs+"/"+fm);
	}
}

Test2_2.java

package practice2_2;
import java.util.Scanner;

public class Test2_2 {
     
	public static void main(String[] args) {
     
		Fractions fractions =  new Fractions();
		@SuppressWarnings("resource")
		Scanner inTo = new Scanner(System.in);
		int fson1 = 0;
		int fson2 = 0;
		int fmom1 = 0;
		int fmom2 = 0;
		System.out.println("请输入第一个分数的分子：");
		fson1 = inTo.nextInt();
		System.out.println("请输入第一个分数的分母：");
		fmom1 = inTo.nextInt();
		System.out.println("请输入第二个分数的分子：");
		fson2 = inTo.nextInt();
		System.out.println("请输入第二个分数的分母：");
		fmom2 = inTo.nextInt();
		System.out.println("运算...");
		fractions.fAdd(fson1, fmom1, fson2, fmom2);
		fractions.fSub(fson1, fmom1, fson2, fmom2);
		fractions.fMul(fson1, fmom1, fson2, fmom2);
		fractions.fDiv(fson1, fmom1, fson2, fmom2);
	}
}

3：设计一个雇员类，创建雇员类对象，统计雇员的出勤人数。

属性包括：编号、姓名、年龄、职务、部门、出勤人数
方法包括：构造方法、输出信息的方法、签到方法

Employee.java

package practice3;
import java.util.Scanner;

public class Employee {
     
	Scanner inTo = new Scanner(System.in);
	public String[] num = new String[1024];		//编号 用数组来存储一组数据
	public String[] name = new String[1024];	//姓名
	public String[] age = new String[1024];		//年龄		//本来是int类型的，因为输入时会出问题，所以也换成了String
	public String[] position = new String[1024];		//职务
	public String[] department = new String[1024]; 	//部门
	public int attendance_data = 0;	//出勤人数
	public Employee() {
     		//构造方法
		
	}
	public void inFormation() {
     
		System.out.println("出勤人数："+attendance_data);
		for(int i = 0;i<attendance_data;i++) {
     
			System.out.println("编号："+num[i]);
			System.out.println("姓名："+name[i]);
			System.out.println("年龄："+age[i]);
			System.out.println("职务："+position[i]);
			System.out.println("部门："+department[i]);
		}
	}
	public void sign() {
     
		int i = 0;
		/*System.out.println("请输入出勤人数：");
		attendance_data = inTo.nextInt();*/
		for(i = 0;i<2;i++) {
     
			System.out.println("请输入编号：");
			num[i] = inTo.nextLine();
			System.out.println("请输入姓名：");
			name[i] = inTo.nextLine();
			System.out.println("请输入年龄：");
			age[i] = inTo.nextLine();
			System.out.println("请输入职务：");
			position[i] = inTo.nextLine();
			System.out.println("请输入部门：");
			department[i] = inTo.nextLine();
			System.out.println("如果你是最后一个签到的人请输入over，如果不是请输入1");
			String flag = inTo.nextLine();	//这个和age的处境一样，不是String类型输入时会出问题
			if(flag.equals("over")) break;	//字符串比较需要用equals方法
		}
		attendance_data = i+1;
	}
}

Test3.java

package practice3;

public class Test3 {
     
	public static void main(String[] args) {
     
		Employee employee = new Employee();
		System.out.println("开始签到...");
		employee.sign();
		System.out.println("签到完毕!");
		employee.inFormation();
	}
}

4：仿照超市购物的例子编写一个学生借书的程序。

提示：
•思考需要定义的类，例如：本程序需要用到学生、借书卡、书等对象，最后实现借书的过程，如果有指定的书，则输出“***借到了***书”，否则输出“没有借到书”。
•还需要认真思考每个类中有哪些属性和方法，能够更好的完成这个程序。

只能说，完全没找到超市购物的例子。。。
下面代码只是个表面

Student.java

package practice4;

public class Student {
     
	public String studentName;
	public Student(String studentName) {
     
		this.studentName = studentName;
	}
	public String printName() {
     
		return this.studentName;
	}
}

Book.java

package practice4;

public class Book {
     
	public String bookName;
	public Book(String bookName) {
     
		this.bookName = bookName;
	}
	public String printName() {
     
		return this.bookName;
	}
}

LibraryCard.java

package practice4;

public class LibraryCard {
     
	public String privilege;
	public LibraryCard(String privilege) {
     
		this.privilege = privilege;
		System.out.println("您的借书卡拥有权限："+privilege);
	}
	public void printlnPrivilege() {
     
		System.out.println("借书卡拥有权限："+privilege);
	}
}

Test4.java

package practice4;

public class Test4 {
     
	public static void main(String[] args) {
     
		Student student = new Student("HaoLong");
		Book book = new Book("DataStructure");
		LibraryCard libraryCard = new LibraryCard("Root privilege");
		System.out.println("借书同学："+student.printName());
		System.out.println("要借书名称："+book.printName());
		System.out.println("借书需要权限：Root privilege");
		libraryCard.printlnPrivilege();
		if(libraryCard.privilege.equals("Root privilege"))
			System.out.println(student.studentName+"借到了"+book.bookName);
		else 
			System.out.println(student.studentName+"没借到"+book.bookName);
	}
}

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