自测代码（方法与面向对象的应用【求区间质数、求100个随机数中的最小数、阶乘、图书管理类的应用】）-2021-7-21

MyClass类

package com.qianfeng.day07;

public class MyClass {
	
	//输出三角形的行数
	public void printTriangle(int n) {
		for (int i = 1; i <= n; i++) {
			for (int j = 0; j < 2*i-1; j++) {
				System.out.print("*");
			}
			System.out.println();
		}
	}
	
	//返回区间[left,right]中质数的个数
	public int primeNumber(int left, int right) {
		int number = 0;
		for (int i = left; i <= right; i++) {
			int j;
			for (j = 2; j < i; j++) {
				if (i%j == 0) {
					break;
				}
			}
			if (i == j) {
				number++;
			}
		}
		return number;
	}
	
	//返回100个随机数中的最小值
	public int randomNumber(int n) {
		int min;
		int[] number = new int[100];
		for (int i = 0; i < 100; i++) {
			number[i] = (int)(Math.random()*n+1);
		}
		min = number[0];
		for (int i = 0; i < number.length; i++) {
			if (number[i] < min) {
				min = number[i];
			}
		}
		return min;
	}
	
	//求一个数的阶乘
	public int factorial(int n) {
		int number = 1;
		for (int i = 1; i <= n; i++) {
			number = number * i;
		}
		return number;
	}
}

LibraryManager类

package com.qianfeng.day07;

public class LibraryManager {
	
	String[] bookNames = new String[10];
	double[] price = new double[10];
	
	public LibraryManager() {
		this.bookNames[0] = "老人与海";
		this.price[0] = 32;
		this.bookNames[1] = "活着";
		this.price[1] = 27;
		this.bookNames[2] = "红与黑";
		this.price[2] = 21;
		this.bookNames[3] = "西游记";
		this.price[3] = 26;
		this.bookNames[4] = "水浒传";
		this.price[4] = 28;
		this.bookNames[5] = "三国演义";
		this.price[5] = 30;
		this.bookNames[6] = "红楼梦";
		this.price[6] = 36;
		this.bookNames[7] = "小王子";
		this.price[7] = 38;
		this.bookNames[8] = "悲惨世界";
		this.price[8] = 40;
		this.bookNames[9] = "巴黎圣母院";
		this.price[9] = 42;
	}
	
	//1.根据传入的书名查找某本书的价格并返回给用户（如果图书不存在则显示没有这本书）
	public double inquire(String bookName) {
		double price = 0;
		for (int i = 0; i < 10; i++) {
			if (bookName == this.bookNames[i]) {
				price = this.price[i];
			}
		}
		if (price == 0) {
			System.out.println("查无此书");
		}
		return price;
	}
	
	//2.向客户展示目前所有的图书信息
	public void printBook() {
		for(int i = 0; i < 10; i++) {
			System.out.println("第" + (i+1) + "本书为：" + this.bookNames[i] + ",价格为：" + this.price[i]);
		}
	}
	
	//3.显示单价最高的前3本书的信息（书名和价格）
	public void maxPrice() {
		double temp;
		//备份价格表
		double[] xprice = new double[10];
		for (int i = 0; i < xprice.length; i++) {
			xprice[i] = this.price[i];
		}
		//冒泡排序选出最大的三个数在数组最后
		for (int i = 0; i < 3; i++) {
			for (int j = 0; j < 10-1; j++) {
				if (xprice[i] > xprice[i+1]) {
					temp = xprice[i];
					xprice[i] = xprice[i+1];
					xprice[i+1] = temp;
				}
			}
		}
		System.out.println("价格最高的三本书信息如下：");
		//将最大的三个价格与原来价格表进行比较，选出其对应书籍
		for (int i = 9; i > 6; i--) {
			for (int j = 0; j < 10; j++) {
				if (xprice[i] == this.price[j]) {
					System.out.print("本书为：" + this.bookNames[j]);
				}
			}
			System.out.println(",价格为：" + xprice[i]);
			
		}
		
	}
	
	//4.根据传入的书名删除这本书，删除完成后显示一下最新的图书情况
	public void deleteBook(String bookName) {
		int index = 0;
		for (int i = 0; i < 10; i++) {
			if (bookName == this.bookNames[i]) {
				index = i;
			}
		}
		for (int i = index; i < 9; i++) {
			this.bookNames[i] = this.bookNames[i+1];
			this.price[i] = this.price[i+1];
		}
		for (int i = 0; i < 9; i++) {
			System.out.println(this.bookNames[i] + "价格为：" + this.price[i]);
		}
	}

}

work类（测试类）

package com.qianfeng.day07;

public class Work {
	public static void main(String[] args) {
		MyClass myClass = new MyClass();
		//输出三角形行数
		System.out.println("输入的行数是：5");
		myClass.printTriangle(5);
		System.out.println();
		//返回区间质数的个数
		System.out.println("区间是[1,100]");
		System.out.println("有："+ myClass.primeNumber(1, 10) + "个质数");
		System.out.println();
		//返回一百个随机数的最小值
		System.out.println("随机数设置为：1000");
		System.out.print("最小的那个随机数为：");
		System.out.println(myClass.randomNumber(1000));
		System.out.println();
		//返回一个数的阶乘
		System.out.print("5!=");
		System.out.println(myClass.factorial(5));
		System.out.println("\n\n");
		
		//测试图书管理类
		LibraryManager libraryManager = new LibraryManager();
		System.out.print("查询的书是红与黑，价格为：");
		System.out.println(libraryManager.inquire("红与黑"));
		System.out.println();
		
		System.out.println("所有书籍信息为");
		libraryManager.printBook();
		System.out.println();
		
		libraryManager.maxPrice();
		System.out.println();
		
		System.out.println("删除的书籍为活着");
		libraryManager.deleteBook("活着");
		
	}

}