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面向对象编程练习题

news 2025/10/28 7:58:38

package oop_Homework;public class Homework01 {public static void main(String[] args) {Person[] persons = new Person[3];//初始化Person对象数组，有三个person对象persons[0] = new Person("smith",10,"java工程师");persons[1] = new Person("tom",50,"大数据工程师");persons[2] = new Person("mary",30,"PHP工程师");//输出对象数组for (int i = 0; i < persons.length; i++) {System.out.println(persons[i]);//默认对象的。tostring（），方法已经重写  tostring 已经重写输出对象的属性}System.out.println("========冒泡排序后========");Person tmp = null;//临时变量，用于交换数据for (int i = 0; i < persons.length - 1; i++) {for (int j = 0; j < persons.length - i; j++) {//按照 age 从大到小 进行排序，如果 前面人的 age 小于后面人的年龄 就交换if (persons[i].getName().length() > persons[i + 1].getName().length()){tmp = persons[i + 1];persons[i + 1] = persons[i];persons[i] = tmp;}}}for (int i = 0; i < persons.length; i++) {System.out.println(persons[i]);//默认对象的。tostring（），方法已经重写  tostring 已经重写输出对象的属性}}
}
class Person{private String name;private int age;private String job;public Person(String name, int age, String job) {this.name = name;this.age = age;this.job = job;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public String getJob() {return job;}public void setJob(String job) {this.job = job;}@Overridepublic String toString() {return "Person{" +"name='" + name + '\'' +", age=" + age +", job='" + job + '\'' +'}';}
}

同类同包不同包子类不同包非子类

public 可以可以可以可以

protect 可以可以可以不可以

默认可以可以不可以不可以

private 可以不可以不可以不可以

public公共同包同类子类不同包都可使用

private受保护同包同类子类可以使用不同包不可使用

默认修饰符同包同类可以使用子类不可使用不同包不可使用

private私有同类可以使用同包同类不同包不可使用

package oop_Homework.Homework03;public class Homework03 {public static void main(String[] args) {Professor professor = new Professor("老高",50,"高级职称",12000,1.3);a_Professor aProfessor = new a_Professor("老中", 49, "中级职称", 11000, 1.2);Lectuer lectuer = new Lectuer("老讲", 48, "初级职称", 10000, 1.1);professor.introduce();aProfessor.introduce();lectuer.introduce();}
}
class Teacher{private String name;private int age;private String post;private double salary;private double grade;public Teacher(String name, int age, String post, double salary, double grade) {this.name = name;this.age = age;this.post = post;this.salary = salary;this.grade = grade;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public String getPost() {return post;}public void setPost(String post) {this.post = post;}public double getSalary() {return salary;}public void setSalary(double salary) {this.salary = salary;}public double getGrade() {return grade;}public void setGrade(double grade) {this.grade = grade;}public void introduce(){System.out.println("name:" + name + "age:" +  age + "post:" + post + "salary:" + salary + "grade:" + grade);}
}

package oop_Homework.Homework04;public class Emlpoyee {private String name;private double salary;private double days;private double grade;public Emlpoyee(String name, double salary, double days, double grade) {this.name = name;this.salary = salary;this.days = days;this.grade = grade;}public String getName() {return name;}public void setName(String name) {this.name = name;}public double getSalary() {return salary;}public void setSalary(double salary) {this.salary = salary;}public double getDays() {return days;}public void setDays(double days) {this.days = days;}public double getGrade() {return grade;}public void setGrade(double grade) {this.grade = grade;}public void sumsal(){System.out.println(name + " 工资=" + salary*days*grade);}
}

package oop_Homework.Homework04;public class worker extends Emlpoyee{public worker(String name, double salary, double days, double grade) {super(name, salary, days, grade);}@Overridepublic void sumsal() {super.sumsal();}
}

package oop_Homework.Homework04;public class manager extends Emlpoyee{private double bonus;public manager(String name, double salary, double days, double grade, double bonus) {super(name, salary, days, grade);this.bonus = bonus;}public double getBonus() {return bonus;}public void setBonus(double bonus) {this.bonus = bonus;}@Overridepublic void sumsal() {System.out.println("经理" + getName() + "工资是=" + (bonus + (getSalary()*getDays()*getGrade())));}
}

package oop_Homework.Homework04;public class Homework04 {public static void main(String[] args) {worker worker01 = new worker("老张", 200, 26, 1);manager manager01 = new manager("老李", 300,26, 1.2,1000);worker01.sumsal();manager01.sumsal();}
}

package Homework05;public class Employee {private String name;private String job;private double sal;public Employee(String name, String job, double sal) {this.name = name;this.job = job;this.sal = sal;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getJob() {return job;}public void setJob(String job) {this.job = job;}public double getSal() {return sal;}public void setSal(double sal) {this.sal = sal;}public void yearsal(){System.out.println("全年的工资是：" + (12*getSal()));}
}

package Homework05;public class Worker extends Employee{public Worker(String name, String job, double sal) {super(name, job, sal);}@Overridepublic void yearsal() {System.out.println(getName() + getJob());super.yearsal();}
}

package Homework05;public class Teacher extends Employee{private double classSal;private double classDay;public Teacher(String name, String job, double sal, double classSal, double classDay) {super(name, job, sal);this.classSal = classSal;this.classDay = classDay;}public double getClassSal() {return classSal;}public void setClassSal(double classSal) {this.classSal = classSal;}public double getClassDay() {return classDay;}public void setClassDay(double classDay) {this.classDay = classDay;}@Overridepublic void yearsal() {System.out.println(getName() + getJob() + "全年的工资是：" + (classDay*classSal + 12 * getSal()) );}
}

package Homework05;public class Scientist extends Employee{private double bonus;public Scientist(String name, String job, double sal, double bonus) {super(name, job, sal);this.bonus = bonus;}public double getBonus() {return bonus;}public void setBonus(double bonus) {this.bonus = bonus;}@Overridepublic void yearsal() {System.out.println(getName() + getJob() + "全年工资是:" + (getBonus() + 12 * getSal()));}
}

package Homework05;import com.sun.deploy.util.Waiter;public class Homework05 {public static void main(String[] args) {Peasant peasant = new Peasant("johe", "农民", 4500);peasant.yearsal();Worker worker = new Worker("sam", "工人", 4000);worker.yearsal();Teacher teacher = new Teacher("chuanpu", "教师", 4000, 25, 100);teacher.yearsal();Scientist scientist = new Scientist("tagna", "科学家", 5000, 10000);scientist.yearsal();}
}

super可以调用父类的属性和方法，但是得有访问权限

this指从本类开始查找，本来没有开始查找父类的

package Homework07;public class Test {String name = "rose";Test(){System.out.println("Test");}Test(String name){this.name = name;}
}
class Demo extends Test{String name = "Jack";Demo(){super();System.out.println("Demo");}Demo(String s){super(s);}public void test(){System.out.println(super.name);System.out.println(this.name);}public static void main(String[] args) {new Demo().test();new Demo("john").test();}
}

Test
Demo
rose
Jack
john
Jack

package Homework08;public class BankAccount {private double balance;public BankAccount(double initialBalance){this.balance = initialBalance;}public void deposit(double amount){balance += amount;}public void withdraw(double amount){balance -= amount;}public double getBalance() {return balance;}public void setBalance(int balance) {this.balance = balance;}
}

package Homework08;public class CheckingAccount extends BankAccount{public CheckingAccount(double initialBalance) {super(initialBalance);}@Overridepublic void deposit(double amount) {super.deposit(amount - 1);}@Overridepublic void withdraw(double amount) {super.withdraw(amount + 1);}
}

package Homework08;public class SavingAccount extends BankAccount{private int count = 3;private double rate = 0.01;public void earnMonthlyInterest(){//每个月初，我们将统计上个月的利率，同时将count = 3count = 3;super.deposit(getBalance() * rate);}@Overridepublic void deposit(double amount) {//判断是否还可以免手续费if (count > 0){super.deposit(amount);}else {super.deposit(amount - 1);//1 块转入银行}count--;//减去一次}@Overridepublic void withdraw(double amount) {if (count > 0){super.withdraw(amount);}else {super.deposit(amount + 1);}count --;}public SavingAccount(double initialBalance) {super(initialBalance);this.count = count;}public int getCount() {return count;}public void setCount(int count) {this.count = count;}public double getRate() {return rate;}public void setRate(double rate) {this.rate = rate;}
}

package Homework08;public class Homework08 {public static void main(String[] args) {
//        CheckingAccount checkingAccount = new CheckingAccount(1000);
//        checkingAccount.deposit(10);
//        checkingAccount.withdraw(9);
//        System.out.println(checkingAccount.getBalance());SavingAccount savingAccount = new SavingAccount(1000.0);savingAccount.deposit(100);savingAccount.deposit(100);savingAccount.deposit(100);System.out.println(savingAccount.getBalance());savingAccount.deposit(100);System.out.println(savingAccount.getBalance());savingAccount.earnMonthlyInterest();System.out.println(savingAccount.getBalance());savingAccount.withdraw(100);savingAccount.withdraw(100);savingAccount.withdraw(100);System.out.println(savingAccount.getBalance());savingAccount.deposit(100);System.out.println(savingAccount.getBalance());}
}

package Homework09;public class Point {private double x;private double y;public Point(double x, double y) {this.x = x;this.y = y;}public double getX() {return x;}public void setX(double x) {this.x = x;}public double getY() {return y;}public void setY(double y) {this.y = y;}
}

package Homework09;public class LabeledPoint extends Point{private String label;public LabeledPoint(double x, double y, String label) {super(x, y);this.label = label;}
}

package Homework09;public class Homework09 {public static void main(String[] args) {LabeledPoint blackpeace = new LabeledPoint(128, 213.9, "blackpeace");}
}

package Homework10;public class Doctor {private String name;private int age;private String job;private char gender;private double sal;public Doctor(String name, int age, String job, char gender, double sal) {this.name = name;this.age = age;this.job = job;this.gender = gender;this.sal = sal;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public String getJob() {return job;}public void setJob(String job) {this.job = job;}public char getGender() {return gender;}public void setGender(char gender) {this.gender = gender;}public double getSal() {return sal;}public void setSal(double sal) {this.sal = sal;}public boolean equals(Object obj){if (this == obj){return true;}if (!(obj instanceof Doctor)){return false;}//向下转型，因为obj的运行类型是Doctor或者是其子类型Doctor doctor = (Doctor)obj;return this.name.equals(doctor.name) && this.age == doctor.age && this.gender == doctor.gender && this.job.equals(doctor.job) && this.sal == doctor.sal;}
}

package Homework10;public class Homework10 {public static void main(String[] args) {Doctor doctor1 = new Doctor("jack", 20, "牙科医生", '男', 20000);Doctor doctor2 = new Doctor("jack", 20, "牙科医生", '男', 20000);System.out.println(doctor1.equals(doctor2));}
}

package Homework11;public class Person {public void run(){System.out.println("person run");}public void eat(){System.out.println("person eat");}
}

package Homework11;public class Student extends Person{@Overridepublic void run() {System.out.println("Student run");}public void study(){System.out.println("Student study...");}
}
/*答案：
* 向上转型:父类的引用指向子类对象
* Person p = new Student();
* p.run(); //student run;
* p.eat(); //person eat;
*
* 向下转型：把指向子类对象的父类引用，转成指向子类对象的子类引用
* Student s = (Student)p;
* s.run();//student run;
* s.study();//student study...
* s.eat();//person eat
* */

package Homework12;public class Person {private String name;private char sex;private int age;public Person(String name, char sex, int age) {this.name = name;this.sex = sex;this.age = age;}public String getName() {return name;}public void setName(String name) {this.name = name;}public char getSex() {return sex;}public void setSex(char sex) {this.sex = sex;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}//编写一个 play 方法，把共有的输出内容写道父类public String play(){return name + "爱玩";}//返回一个基本信息/** 姓名：张飞* 年龄：30* 性别：男* */public String basicInfo(){return "姓名： " + name + "\n年龄： " + age + "性别： " + sex;}@Overridepublic String toString() {return "Person{" +"name='" + name + '\'' +", sex=" + sex +", age=" + age +'}';}
}

package Homework12;public class Student extends Person{private String stu_id;public Student(String name, char sex, int age, String stu_id) {super(name,sex,age);this.stu_id = stu_id;}public String getStu_id() {return stu_id;}public void setStu_id(String stu_id) {this.stu_id = stu_id;}//我承诺会好好学习 javapublic void study(){System.out.println(getName() + "我承诺会好好学习 java");}//学生爱玩@Overridepublic String play() {return super.play() + "足球";}public void printInfo() {System.out.println("学生的信息：");System.out.println(basicInfo());System.out.println("学号： " + stu_id);study();System.out.println(play());}@Overridepublic String toString() {return "Student{" +"stu_id='" + stu_id + '\'' +'}' + super.toString();}
}

package Homework12;public class Teacher extends Person{private int work_age;public Teacher(String name, char sex, int age, int work_age) {super(name,sex,age);this.work_age = work_age;}public void setWork_age(int work_age) {this.work_age = work_age;}//承诺会好好教书public void teach(){System.out.println(getName() + "我承诺会好好教书");}//老师爱玩@Overridepublic String play() {return super.play() + "象棋";}public void printInfo(){System.out.println("老师的信息： ");System.out.println(super.basicInfo());System.out.println("工龄： " + work_age);teach();System.out.println(play());}@Overridepublic String toString() {return "Teacher{" +"work_age=" + work_age +'}' + super.toString();}
}

package Homework12;public class Homework12 {public static void main(String[] args) {Student student = new Student("小明", '男', 15, "00023102");student.printInfo();Teacher teacher = new Teacher("小王", '男', 34, 7);System.out.println("------------------------------------------");teacher.printInfo();//定义多态数组，里面保存2个学生和2个老师，要求按年龄从高到低排序Person[] persons = new Person[4];persons[0] = new Student("jack", '男', 10, "10086");persons[1] = new Student("mary", '男', 10, "10011");persons[2] = new Teacher("jeason", '男', 36, 10);persons[3] = new Teacher("scott", '男', 56, 29);//创建对象Homework12 homework12 = new Homework12();homework12.bubbleSort(persons);//输出排序后的数组System.out.println("-----排序后的数组-----");for (int i = 0; i < persons.length; i++) {System.out.println(persons[i]);}System.out.println("====================");for (int i = 0; i < persons.length; i++) {homework12.test(persons[i]);}}public void test(Person p){if (p instanceof Student){((Student)p).study();} else if (p instanceof Teacher) {((Teacher)p).teach();}else {System.out.println("do nothing......");}}public void bubbleSort(Person[] persons){Person temp = null;for (int i = 0; i < persons.length; i++) {for (int j = 0; j < persons.length - 1 - i; j++) {if (persons[j].getAge() < persons[j + 1].getAge()){temp = persons[j];persons[j] = persons[j + 1];persons[j + 1] = temp;}}}}
}

package Homework14;public class Homework14 {public static void main(String[] args) {C c = new C();}
}
class A{public A(){System.out.println("我是A类");}
}
class B extends A{public B(){System.out.println("我是B类的无参构造");}public B(String name){System.out.println(name + "我是B类的有参构造");}
}
class C extends B{public C(){this("Hello");System.out.println("我是c类的无参构造");}public C(String name){super("hahah");System.out.println("我是C类的有参构造");}
}

我是A类
hahah我是B类的有参构造
我是C类的有参构造
我是c类的无参构造