Java 习题（面向对象）

1.（面向对象基础）写一个Worker 类，并创建多个Worker 对象。

为Worker 类添加四个属性，
<1>int 类型的id，表示工人的编号；
<2>String 类型的name，表示工人的姓名；
<3>int 类型的age，表示工人的年龄；
<4>double 类型的salary，表示工人的工资。
为Worker 类添加两个构造方法，
<1>公开无参构造方法；
<2>接受四个参数的构造方法，四个参数分别为int、字符串、int 和double类型。
为Worker 类添加两个work 方法，一个无参，打印工人姓名工作8小时另一个带整数参数，打印工人姓名以及工作的时间（为多少小时）。

package com.fxm.test;
public class Test1{
	public static void main(String[] args){
		Worker w = new Worker(10086,"xiaobai",18,1800);
		w.work();
		w.work(6);
	}
}
class Worker{
	int id;
	String name;
	int age;
	double salary;
	public Worker(){
		
	}
	public Worker(int id,String name,int age,double salary){
		this.id = id;
		this.name = name;
		this.age = age;
		this.salary = salary;
	}
	public void work(){
		System.out.println(name+" 工作8小时");
	}
	public void work(int hours){
		System.out.println(name+" 工作 "+hours+" 小时");
	}
}

2 ** 、完成如下代码：

public class WorkerArrayTest{ public static void main(String[] args){
//1 、创建一个元素为Worker类型的数组长度为 3
//2 、创建 3 个Worker对象并保存到数组中
//3 、遍历数组，并调用每一个Worker对象的无参work方法
//4 、调用oldWorker函数
}
//写一个函数oldWorker遍历数组返回其中年纪最大的Worker对象
/ / 形参为Worker[]类型返回值为Worker类型
}

package com.fxm.test;
public class Test2{
	public static void main(String[] args){
		Worker[] ws = new Worker[3];
		ws[0] = new Worker("xiaobai",18);
		ws[1] = new Worker("xiaohei",20);
		ws[2] = new Worker("xiaohong",19);
		for(int i = 0; i < ws.length; i++){
			ws[i].work();
		}
		Worker max = oldWorker(ws);
		System.out.println(max.name+"-->"+max.age);
	}
	public static Worker oldWorker(Worker[] ws){
		Worker max = ws[0];
		for(int i = 0; i < ws.length; i++){
			if(max.age < ws[i].age){
				max = ws[i];
			}					
		}
		return max;
	}
}
class Worker{
	String name;
	int age;
	public void work(){}
	public Worker(String name,int age){
		this.name = name;
		this.age = age;
	}
}

3 *** 、定义一个Company类，该类中有一个Worker[]类型属性，保存多个Worker对象。完成如下代码：
public class Company{ Worker[] ws = new Worker[16]; int count = 0; / / 记录ws中有效的元素个数
//完成添加Worker方法
public void addWorker(Worker w){
//如果ws已满，扩容
//添加 w
//将count递增 1
}
//完成方法
返回每月公司需要支付的薪资
public double getAllSalaries(){ / / 遍历数组，并计算总额 }
//完成方法
判断一个给定的 W o r k e r 对象是否属于当前公司（通过 i d 判断） public boolean contains(Worker w){
//遍历数组进行判断
} }

package com.fxm.test;
public class Test3{
	public static void main(String[] args){
		Company c = new Company();
		//添加员工
		Worker w1 = new Worker(1,"zhang3",18,18000.0);
		Worker w2 = new Worker(2,"li4",20,20000.0);
		Worker w3 = new Worker(3,"wang5",16,16000.0);
		
		c.addWorker(w1);
		c.addWorker(w2);
		
		double sum  = c.getAllSalaries();
		System.out.println(sum);
		
		System.out.println(c.contains(w1));
		System.out.println(c.contains(w3));
	}
}
class Company{
	Worker[] ws = new Worker[16];
	int count = 0;
	public void addWorker(Worker w){
		if(count == ws.length){
			ws = java.util.Arrays.copyOf(ws,ws.length << 1);
		}
		ws[count] = w;
		count++;
	}
	public double getAllSalaries(){
		double sum = 0.0;
		for(int i = 0; i < count; i++){
			sum += ws[i].salary;
		}
		return sum;
	}
	public boolean contains(Worker w){
		for(int i = 0; i < count; i++){
			if(ws[i].id == w.id){
				return true;
			}
		}
		return false;
	}
}

4.（封装）已知一个类Student 代码如下：

class Student{
	String name;
	int age;
	String address;
	String zipCode;
	String mobile; 
	}

把Student 的属性都作为私有，并提供get/set 方法以及适当的构造方法。
为Student 类添加一个getPostAddress 方法，要求返回Student 对象的地址和邮编。

package com.fxm.test;
public class Test4{
	public static void main(String[] args){
		Student s = new Student();
		s.setName("xiaobai");
		s.setAddress("nanyang");
		s.setZipCode("474250");
		s.study(6);
		System.out.println(s.getPostAddress());
	}
}
class Student{
	private String name;
	private int age;
	private String address;
	private String zipCode;
	private String mobile;
	public String getName(){
		return name;
	}
	public void setName(String newName){
		name = newName;
	}
	public int getAge(){
		return age;
	}
	public void setAge(int newAge){
		age = newAge;
	}
	public String getAddress(){
		return address;
	}
	public void setAddress(String newAddress){
		address = newAddress;
	}
	public String getZipCode(){
		return zipCode;
	}
	public void setZipCode(String newZipCode){
		zipCode = newZipCode;
	}
	public String getMobile(){
		return mobile;
	}
	public void setMobile(String newMobile){
		mobile = newMobile;
	}
	public void study(int hours){
		System.out.println(name+"ѧϰ"+hours+"Сʱ");
	}
	public String getPostAddress(){
		return address+zipCode;
	}
}

5、 *** .使用day07的Teacher类和Student类
类 Clazz //该类对象表示一个班级
属性
Teacher t
Student[] ss = new Student[10];//保存多个Student对象
int count;//表示有效元素个数
方法：
addStudent(Student s);//添加Student对象
removeStudent(int id);//根据id移除Student对象 updateStudent(Student s);//更新Student对象
queryStudent(int id);//根据id查询Student对象

package com.fxm.test;
public class Test5{
	public static void main(String[] args){
		Clazz c = new Clazz();
		Student s1 = new Student(1,"xiao1hei",16,'男');
		Student s2 = new Student(2,"xiao2hei",16,'男');
		Student s3 = new Student(3,"xiao3hei",16,'男');
		Student s4 = new Student(4,"xiao4hei",16,'男');
		
		c.addStudent(s1);
		c.addStudent(s2);
		c.addStudent(s3);
		c.addStudent(s4);
		
		s4.age = 18;
		c.updateStudent(s4);
		Student s = c.queryStudent(4);
		System.out.println(s.name+"-->"+s.age);
		
		c.removeStudent(4);
		System.out.println(c.queryStudent(4));
		
	}
}
class Student{
	int id;
	String name;
	int age;
	char sex;
	public Student(int id,String name,int age,char sex){
		this.id = id;
		this.name = name;
		this.age = age;
		this.sex = sex;
	}
	public void study(){
		System.out.println(name+"学习8小时");	
	}
	public void study(int hours){
		System.out.println(name+"学习"+hours+"小时");
	}
}

class Teacher{
	int id;
	String name;
	String course;
	public void teach(){
		System.out.println(name+"教"+course);
	}
}

class Clazz{
	Student[] ss = new Student[10];
	Teacher t;
	int count;
	
	public void addStudent(Student s){
		if(ss.length == count){
			ss = java.util.Arrays.copyOf(ss,ss.length << 1);
		}
		ss[count] = s;
		count++;
	}
	public void removeStudent(int id){
		int index = -1;
		for(int i = 0; i < count; i++){
			if(ss[i].id == id){
				index = i;
				break;
			}
		}
		if(index == -1){
			return;
		}
		System.arraycopy(ss,index+1,ss,index,count-index-1);
		count--;
	}
	public boolean updateStudent(Student s){
		for(int i = 0; i < count; i++){
			if(ss[i].id == s.id){
				ss[i] = s;
				return true;
			}
		}
		return false;
	}
	public Student queryStudent(int id){
		for(int i = 0; i < count; i++){
			if(ss[i].id == id){
				return ss[i];
			}
		}
		return null;
	}
}

6、按类图要求写出所有的类
Instrument表示乐器类，play方法打印输出”弹奏乐器”
Wind继承Instrument，重写play方法，打印输出”弹奏Wind”
并提供另外一个playWind方法，打印输出”调用wind的play2方法”
Brass继承Instrument，重写play方法，打印输出”弹奏Brass”
并提供另外一个playBrass方法，打印输出”调用Brass的play2方法”

package com.fxm.test;
public class Test6{
    public static void main(String args[]){
        Wind w = new Wind();
		w.play();
		w.playWind();
		Brass b = new Brass();
		b.play();
		b.playBrass();
	}
}
class Instrument{
	public void play(){
		System.out.println(" 弹奏乐器");
	}
}
class Wind extends Instrument{
	public void play(){
		System.out.println(" 弹奏Wind");
	}
	public void playWind(){
		System.out.println(" 调用Wind的play2方法");
	}
}
class Brass extends Instrument{
	public void play(){
		System.out.println(" 弹奏Brass");
	}
	public void playBrass(){
		System.out.println(" 调用Brass的play2方法");
	}
}

7.（封装、继承）有以下几个类，根据下面的继承关系，用 Java 代码实现。
a) Circle 类（圆形），属性：半径；方法：求周长、求面积
b) Rect 类（矩形），属性：长、宽；方法：求周长、求面积
c) Square 类（正方形），属性：边长；方法：求周长、求面积
提示：
1）三个子类各自有其属性，圆：radius半径矩形：length长 width宽正方形： length边长;
2）父类中的周长(girth)和面积(area)的方法统一返回0.0，在三个子类中重写两个方法
圆周长公式：3.142r 面积公式：3.14rr
矩形周长公式：(length+width)2 面积公式 lengthwidth
正方形：周长公式 length4 面积公式 lengthlength

package com.fxm.test;
public class Test7{
    public static void main(String args[]){
        Circle c = new Circle();
		c.area();
		c.girth();
	}
}
class Shape{
	public double area(){		
		return 0.0;
	}
	public double girth(){
		return 0.0;
	}
}
class Circle extends Shape{
	double radius;
	public Circle(){}
	public Circle(double radius){
		this.radius = radius;
	}
	public void setRadius(double radius){
		this.radius = radius;
	}
	public double getRadius(){
		return radius;
	}
	public double area(){
		return (3.14*radius*radius);
	}
	public double girth(){
		return (6.28*radius);
	}
}
class Rect extends Shape{
	private double length;
	private double width;
	public void Rect(){}
	public void Rect(double length,double width){
		this.length = length;
		this.width = width;
	}
	public void setLength(double length){
		this.length = length;
	}
	public void setWidth(double width){
		this.width = width;
	}
	public double getLength(){
		return length;
	}
	public double getWidth(){
		return width;
	}
	public double area(){
		return (length*width);
	}
	public double girth(){
		return ((length+width)*2);
	}
}
class Square extends Shape{
	private double length;
	public void setLength(double length){
		this.length = length;
	}
	public double getLength(){
		return length;
	}
	public double area(){
		return (length*length);
	}
	public double girth(){
		return (length*4);
	}
}

8.（封装、继承、super）某公司的雇员分为以下若干类：

Employee：这是所有员工总的父类，属性：员工的姓名,员工的生日月份。方法：getSalary(intmonth) 根据参数月份来确定工资，如果该月员工过生日，则公司会额外奖励100 元。

SalariedEmployee：Employee 的子类，拿固定工资的员工。属性：月薪

HourlyEmployee： Employee 的子类，按小时拿工资的员工，每月工作超出160 小时的部分按照1.5 倍工资发放。属性：每小时的工资、每月工作的小时数

SalesEmployee：Employee 的子类，销售人员，工资由月销售额和提成率决定。属性：月销售额、提成率

BasePlusSalesEmployee：SalesEmployee 的子类，有固定底薪的销售人员，工资由底薪加上销售提成部分。属性：底薪。

根据要求创建 SalariedEmployee 、 HourlyEmployees 、SaleEmployee 和 BasePlusSalesEmployee四个类的对象各一个，并计算某个月这四个对象的工资。
注意：要求把每个类都做成完全封装，不允许非私有化属性。

package com.fxm.test;

public class Employee {
	
	public Employee(String name, int month){
		this.name = name;
		this.month = month;
	}
	
	public float get_Salary(int month){
		//如果月份为员工生日月份，则增加100
		if(month == this.month){
			return 100;
		}
		else{
			return 0;
		}
	}
	
	private String name;
	private int month;
	
	public static void main(String[] args) {
		Employee a[] = new Employee[4];
		
		a[0] = new SalariedEmployee("A", 2, 1000);
		a[1] = new HourlyEmployee("B", 3, 2000, 200);
		a[2] = new SalesEmployee("C", 4, 50000, (float) 0.1);
		a[3] = new BasedPlusSalesEmployee("D", 5, 50000, (float) 0.1, 1000);
		
		System.out.println("A的工资为" + a[0].get_Salary(2));
		System.out.println("B的工资为" + a[1].get_Salary(2));
		System.out.println("C的工资为" + a[2].get_Salary(2));
		System.out.println("D的工资为" + a[3].get_Salary(2));
	}
}

class SalariedEmployee extends Employee{
	public SalariedEmployee(String name, int month, float salary)
	{
		super(name, month);
		this.salary = salary;	
	}
	
	@Override
	public float get_Salary(int month)
	{
		return salary + super.get_Salary(month);  
	}
	
	private float salary;
}
class HourlyEmployee extends Employee
{
	public HourlyEmployee(String name, int month, float salary, int hour)
	{
		super(name, month);
		this.salary = salary;
		this.hour = hour;
	}
	
	@Override
	public float get_Salary(int month)
	{
		//大于160小时的情况
		if (hour > 160)
		{
			return (float) (salary * 160 + (hour - 160) * salary * 1.5 
					+ super.get_Salary(month));
		}
		else
		{
			return salary * hour + super.get_Salary(month);
		}
	}
	
	private float salary;  //每小时工资
	private int hour;    //每月工作的小时数
}
 
//销售人员
class SalesEmployee extends Employee
{
	public SalesEmployee(String name, int month, float sale, float bonus)
	{
		super(name, month);
		this.sale = sale;
		this.bonus = bonus;
	}
	
	@Override
	public float get_Salary(int month)
	{
		return sale * bonus + super.get_Salary(month);
	}
	
	private float sale;  //销售额
	private float bonus;  //提成率
}
 
//有固定底薪的销售人员
class BasedPlusSalesEmployee extends SalesEmployee
{
	public BasedPlusSalesEmployee(String name, int month, float sale,
			float bonus, float baseSalary)
	{
		super(name, month, sale, bonus);
		this.baseSalary = baseSalary;
	}
	
	@Override
	public float get_Salary(int month)
	{
		return baseSalary + super.get_Salary(month);
	}
	
	private float baseSalary; //底薪
}

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