Java期末复习题之封装-编程知识

点击返回标题->23年Java期末复习-CSDN博客

第1题.

定义一个类Person,定义name和age私有属性，定义有参的构造方法对name和age进行初始化。在测试类中创建该类的2个对象，姓名、年龄分别为lili、19和lucy、20，在屏幕打印出2个对象的姓名和年龄。

public class Main {public static void main(String[] args) {Person p1 = new Person("lily",19);Person p2 = new Person("lucy",20);System.out.println(p1.toString());System.out.println(p2.toString());}
}
class Person{private String name;private int age;//有参构造给对象赋值Person(String name,int age){this.name = name;this.age = age;}//toString返回由name和age组成的预定字符串public String toString() {return "Person{" +"name='" + name + '\'' +", age=" + age +'}';}
}

第2题.

首先定义一个计算长方形面积的类rectangleClass，要求类中有一个定义长方形左上角和右下角座标的构造函数，以及一个通过长方形右下角座标与左上角座标计算长方形面积,并实例化两个长方形进行测试.

public class Main {public static void main(String[] args) {rectangleClass rec1 = new rectangleClass(-5, 3, -3, 1);rectangleClass rec2 = new rectangleClass(2, -3, 4, -6);System.out.println("rec1" + rec1.getPoint() + "其面积为：" + rec1.getArea());System.out.println("rec2" + rec2.getPoint() + "其面积为：" + rec2.getArea());}
}
class rectangleClass {int x1, y1, x2, y2;//有参构造，定义长方形左上角和右下角座标rectangleClass(int x1, int y1, int x2, int y2) {this.x1 = x1;this.x2 = x2;this.y1 = y1;this.y2 = y2;}//返回计算的面积double getArea() {return Math.abs(x1 - x2) * Math.abs(y1 - y2);}//获取当前长方形左上角点和右下角点的坐标String getPoint() {return "左上角坐标为:(" + this.x1 + "," + this.y1 + ")，" + "右下角角坐标为:(" + this.x2 + "," + this.y2 + ")，";}
}

第3题.

设计一个表示图书的Book类，它包含图书的书名、作者、月销售量等私有属性，另有两个构造方法（一个不带参数，另一个带参数），成员方法setBook( ) 和printBook()分别用于设置和输出书名、作者、月销售量等数据。并设计相应的测试Book类的应用程序主类，测试并显示输出提供所有功能的结果。

public class Main {public static void main(String[] args) {//b1采取有参构造实例化对象并赋值的形式Book b1 = new Book("三体", "刘慈欣", 114514);b1.printBook();//b2采取无参构造实例化对象，调用setBook()成员方法赋值的形式Book b2 = new Book();b2.setBook("龙族", "江南", 10086);b2.printBook();}
}
class Book {private String name, author;private int sale_volume;//无参构造Book() {System.out.println("无参构造被调用");}//有参构造Book(String name, String author, int sale_volume) {System.out.println("有参构造被调用");this.name = name;this.author = author;this.sale_volume = sale_volume;}//设置书本信息void setBook(String name, String author, int sale_volume) {this.name = name;this.author = author;this.sale_volume = sale_volume;}//打印书本信息void printBook() {System.out.printf("书名：%s    作者：%s   月销售量：%d\n", this.name, this.author, this.sale_volume);}
}

第4题.

请创建一个银行帐户类，要求如下：（１）类包括帐户名、帐户号、存款额等私有属性；（3）有三个参数的构造方法（２）可实现余额查询，存款和取款的操作。（３）创建该类的对象，验证以上两项。

import java.util.Scanner;
public class Main {public static void main(String[] args) {Scanner sc = new Scanner(System.in);Bank b1 = new Bank("张三", "123456", 100);int input;do {//循环弹出菜单并请求选择menu();input = sc.nextInt();switch (input) {case 1:b1.getBalance();break;case 2:b1.save_money();break;case 3:if(b1.getBalance()==0){System.out.println("你的账户余额为0，无分文可取！");break;}b1.withdraw_money();break;case 0:System.out.println("已退出，欢迎再次使用！");break;default:System.out.println("该选项尚未开发……");break;}} while (input != 0);}public static void menu() {//打印菜单System.out.println("************************");System.out.println("****** 1.查询余额 ********");System.out.println("****** 2.存款    ********");System.out.println("****** 3.取款    ********");System.out.println("****** 0.退出账户 ********");}static class Bank {private String account_name, account_number;private int balance;public Bank(String account_name, String account_number, int balance) {this.account_name = account_name;this.account_number = account_number;this.balance = balance;}int getBalance() {//余额查询System.out.printf("用户名：%s，当前余额：%d\n", this.account_name, this.balance);return this.balance;}void save_money() {//存钱int save;Scanner sc = new Scanner(System.in);while (true) {System.out.println("你要存多少钱？请输入->");save = sc.nextInt();if (save <= 0) {System.out.println("请输入合理的存款数！");continue;}break;}this.balance += save;System.out.printf("完成存款，本次存款共计%d元，当前余额%d\n", save, this.balance);}void withdraw_money() {//取钱int withdraw;Scanner sc = new Scanner(System.in);while (true) {System.out.println("你要取多少钱？请输入->");withdraw = sc.nextInt();if (withdraw <= 0) {System.out.println("请输入合理的取款数！");continue;} else if (withdraw > this.balance) {System.out.println("你没用这么多钱可供取款！");continue;}break;}this.balance -= withdraw;System.out.printf("完成取款，本次取款共计%d元，当前余额%d\n", withdraw, this.balance);}}
}