Java-黑马Java学习作业-day09面向对象（综合练习）

学习视频链接：https://www.bilibili.com/video/BV17F411T7Ao

文章目录

• • 题目1-对象数组汽车
  • 题目2-对象数组手机
  • 题目3-对象数组女朋友
  • 题目4-复杂对象数组操作

题目1-对象数组汽车

​ 定义数组存储3部汽车对象。

​ 汽车的属性：品牌，价格，颜色。

​ 创建三个汽车对象，数据通过键盘录入而来，并把数据存入到数组当中。

• Car类

package cn.kox.homework01;/*** @ClassName: Car* @Author: Kox* @Data: 2023/1/19* @Sketch:*/
public class Car {private String brand;private int price;private String color;public Car() {}public Car(String brand, int price, String color) {this.brand = brand;this.price = price;this.color = color;}public String getBrand() {return brand;}public void setBrand(String brand) {this.brand = brand;}public int getPrice() {return price;}public void setPrice(int price) {this.price = price;}public String getColor() {return color;}public void setColor(String color) {this.color = color;}
}

• 测试类

package cn.kox.homework01;import java.util.Scanner;/*** @ClassName: Test* @Author: Kox* @Data: 2023/1/19* @Sketch: 题目1*/
public class Test {public static void main(String[] args) {Car[] arr = new Car[3];Scanner sc = new Scanner(System.in);for (int i = 0; i < arr.length; i++) {Car c = new Car();System.out.printf("请输入第%s个汽车的品牌：", i + 1);String brand = sc.next();c.setBrand(brand);System.out.printf("请输入第%s个汽车的价格：", i + 1);int price = sc.nextInt();c.setPrice(price);System.out.printf("请输入第%s个汽车的颜色：", i + 1);String color = sc.next();c.setColor(color);arr[i] = c;}for (int i = 0; i < arr.length; i++) {Car car = arr[i];System.out.printf("%s,%s,%s", car.getBrand(), car.getPrice(), car.getColor());System.out.println();}}
}

题目2-对象数组手机

​ 定义数组存储3部手机对象。

​ 手机的属性：品牌，价格，颜色。

​ 要求，计算出三部手机的平均价格

• Phone类

package cn.kox.homework02;/*** @ClassName: Phone* @Author: Kox* @Data: 2023/1/19* @Sketch:*/
public class Phone {private String brand;private int price;private String color;public Phone() {}public Phone(String brand, int price, String color) {this.brand = brand;this.price = price;this.color = color;}public String getBrand() {return brand;}public void setBrand(String brand) {this.brand = brand;}public int getPrice() {return price;}public void setPrice(int price) {this.price = price;}public String getColor() {return color;}public void setColor(String color) {this.color = color;}
}

• 测试类

package cn.kox.homework02;/*** @ClassName: Test* @Author: Kox* @Data: 2023/1/19* @Sketch: 题目2*/
public class Test {public static void main(String[] args) {Phone p1 = new Phone("小米", 100, "白色");Phone p2 = new Phone("苹果", 150, "蓝色");Phone p3 = new Phone("红米", 50, "红色");Phone[] arr = new Phone[3];arr[0] = p1;arr[1] = p2;arr[2] = p3;int sum = 0;for (int i = 0; i < arr.length; i++) {Phone phone = arr[i];sum += phone.getPrice();}int avg = sum / arr.length;System.out.println(avg);}
}

题目3-对象数组女朋友

​ 定义数组存储4个女朋友的对象

​ 女朋友的属性：姓名、年龄、性别、爱好

​ 要求1：计算出四女朋友的平均年龄

​ 要求2：统计年龄比平均值低的女朋友有几个？并把她们的所有信息打印出来。

• Girlfriend类

package cn.kox.homework03;/*** @ClassName: Girlfriend* @Author: Kox* @Data: 2023/1/19* @Sketch:*/
public class Girlfriend {private String name;private int age;private String gender;private String hobby;public Girlfriend() {}public Girlfriend(String name, int age, String gender, String hobby) {this.name = name;this.age = age;this.gender = gender;this.hobby = hobby;}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 getGender() {return gender;}public void setGender(String gender) {this.gender = gender;}public String getHobby() {return hobby;}public void setHobby(String hobby) {this.hobby = hobby;}
}

• 测试类

package cn.kox.homework03;/*** @ClassName: Test* @Author: Kox* @Data: 2023/1/19* @Sketch:*/
public class Test {public static void main(String[] args) {Girlfriend[] arr = new Girlfriend[4];Girlfriend g1 = new Girlfriend("a", 1, "女", "aa");Girlfriend g2 = new Girlfriend("b", 2, "女", "bb");Girlfriend g3 = new Girlfriend("c", 3, "女", "cc");Girlfriend g4 = new Girlfriend("d", 4, "女", "dd");arr[0] = g1;arr[1] = g2;arr[2] = g3;arr[3] = g4;int sum = 0;for (int i = 0; i < arr.length; i++) {Girlfriend girlfriend = arr[i];sum += girlfriend.getAge();}int avg = sum / arr.length;int count = 0;for (int i = 0; i < arr.length; i++) {Girlfriend girlfriend = arr[i];if (girlfriend.getAge() < avg) {System.out.printf("name:%s, age:%s, gender:%s, hobby:%s", girlfriend.getName(), girlfriend.getAge(), girlfriend.getGender(), girlfriend.getHobby());System.out.println();count++;}}System.out.println(count);}
}

题目4-复杂对象数组操作

​ 定义数组存储3个学生对象。

​ 学生的属性：学号，姓名，年龄。

​ 要求1：添加的时候需要进行学号的唯一性判断。

​ 要求2：添加完毕之后，遍历所有学生信息。

​ 要求3：通过id删除学生信息

​ 如果存在，则删除，如果不存在，则提示删除失败。

​ 要求4：删除完毕之后，遍历所有学生信息。

​ 要求5：id为2的学生，年龄+1岁

• Student类

package cn.kox.homework04;/*** @ClassName: Student* @Author: Kox* @Data: 2023/1/19* @Sketch:*/
public class Student {private int id;private String name;private int age;public Student() {}public Student(int id, String name, int age) {this.id = id;this.name = name;this.age = age;}public int getId() {return id;}public void setId(int id) {this.id = id;}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;}
}

• 测试类

package cn.kox.homework04;/*** @ClassName: Test* @Author: Kox* @Data: 2023/1/19* @Sketch:*/
public class Test {public static void main(String[] args) {Student[] arr = new Student[3];Student s1 = new Student(1, "a", 18);Student s2 = new Student(2, "b", 19);Student s3 = new Student(3, "c", 20);arr[0] = s1;arr[1] = s2;arr[2] = s3;System.out.println("---分割线（添加学生对象）---");// 添加学生对象Student s4 = new Student(4, "d", 21);boolean flag = idJudge(arr, s4.getId());if (flag) {System.out.println("学号重复");} else {int index = arrJudge(arr);if (index == arr.length) {Student[] newArr = creatArr(arr);newArr[index] = s4;printArr(newArr);} else {arr[index] = s4;printArr(arr);}}System.out.println("---分割线（根据id删除信息）---");// 通过id删除学生对象int delId = 3;int delIndex = getIndex(arr, delId);if (delIndex > -1) {arr[delIndex] = null;} else {System.out.println("没有这个学号删除失败！");}printArr(arr);System.out.println("---分割线（查询id加年龄）---");int selectId = 2;int selectIndex = getIndex(arr, selectId);if (selectIndex > -1) {arr[selectIndex].setAge(arr[selectIndex].getAge() + 1);} else {System.out.println("不存在！");}printArr(arr);}public static boolean idJudge(Student[] arr, int id) {for (int i = 0; i < arr.length; i++) {if (arr[i] != null) {if (arr[i].getId() == id) {return true;}}}return false;}public static int arrJudge(Student[] arr) {int count = 0;for (int i = 0; i < arr.length; i++) {if (arr[i] != null) {count++;}}return count;}public static Student[] creatArr(Student[] arr) {Student[] newArr = new Student[arr.length + 1];for (int i = 0; i < arr.length; i++) {newArr[i] = arr[i];}return newArr;}public static void printArr(Student[] arr) {for (int i = 0; i < arr.length; i++) {if (arr[i] != null) {System.out.printf("id: %s, name: %s, age: %s", arr[i].getId(), arr[i].getName(), arr[i].getAge());System.out.println();}}}public static int getIndex(Student[] arr, int id) {for (int i = 0; i < arr.length; i++) {if (arr[i] != null) {if (arr[i].getId() == id) {return i;}}}return -1;}}

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