商品类（ArrayList实现）

       使用ArrayList实现库存管理系统
       定义商品类，属性：商品名(proName)、商品尺寸(proSize)、商品价格(proPrice)、库存量(proNum)
定义商品操作类，方法：查看库存、修改库存、添加库存商品

public class Product {
	int proId;
	String proName;
	double proSize;
	double proPrice;
	int proNum;
	
	public Product() {
		
	}
	
	public Product(int proId, String proName, double proSize, double proPrice, int proNum) {
		super();
		this.proId = proId;
		this.proName = proName;
		this.proSize = proSize;
		this.proPrice = proPrice;
		this.proNum = proNum;
	}
	
	public int getProId() {
		return proId;
	}

	public void setProId(int proId) {
		this.proId = proId;
	}

	public String getProName() {
		return proName;
	}

	public void setProName(String proName) {
		this.proName = proName;
	}

	public double getProSize() {
		return proSize;
	}

	public void setProSize(double proSize) {
		this.proSize = proSize;
	}

	public double getProPrice() {
		return proPrice;
	}

	public void setProPrice(double proPrice) {
		this.proPrice = proPrice;
	}

	public int getProNum() {
		return proNum;
	}

	public void setProNum(int proNum) {
		this.proNum = proNum;
	}
	

	@Override
	public String toString() {
		
		return "  " + proId + "          " + proName + "       " + proSize + "         " + proPrice
				+ "      " + proNum ;
	}
}



/*
*/商品操作类
import java.util.ArrayList;
import java.util.Scanner;

public class ProductOper {
	private ArrayList<Product> pros= new  ArrayList<Product>();
	Scanner input = new Scanner (System.in);
	
	//菜单
	
	public void menu() {
		System.out.println();
		System.out.println("--------库存管理-------");
		System.out.println("1.查看库存清单");
		System.out.println("2.修改商品库存数量");
		System.out.println("3.退出");
		System.out.println("请输入要执行的操作序号：");
	}
	
	//添加库存
	public boolean addProduct(Product pro) {
		if(pros!=null) {
			pros.add(pro);
			return true;
		}
		return false;
	}
	
	//1.查看库存清单
	public void showProduct() {
		System.out.println("－－－－－－－－－商城库存清单－－－－－－－－－");
		System.out.println("编号"+"   "+"品牌型号"+"      "+"尺寸"+"          "+"价格"+"        "+"库存数");
		for(Product pro : pros) {
			System.out.println(pro);
		}
	}
	
	//2.修改商品库存数量	
	public boolean updateStudent(int proId,int proNum) {
		if(pros!=null) {
			//遍历查找要修改的对象
			for(int i=0;i<pros.size();i++) {
				Product p = pros.get(i);			
				if(p.proId == proId) {
					p.proNum = proNum ;
				}					
		    }
			return true;
	    }
        return false;	
	}
}


import java.util.Scanner;

public class ProductTest {
	public static void main(String[] args) {
		ProductOper proOp = new ProductOper();
		Scanner input = new Scanner (System.in);
		
		//1.添加库存
		for(int i=1;i<5;i++) {
			Product pro = new Product();
			pro.proId = i+0;
			pro.proName = "三星"+i;
			pro.proSize = 10.2+i;
			pro.proPrice = 4599+0.11+(i%2);
			pro.proNum = 10+i*2;
			boolean boo = proOp.addProduct(pro);
			if(boo) {
				
			}	
		}
		int number = 0;
		do {
			proOp.menu();
			number = input.nextInt();
			if(number!=3) {
				switch(number) {
				case 1://1.查看库存清单
					proOp.showProduct();
					break;
				case 2://2.修改商品库存数量
					Product pro = new Product();
					System.out.println("请输入你要修改的商品编号：");
					pro.proId=input.nextInt();
					System.out.println("请输入你要修改的库存数量：");
					pro.proNum=input.nextInt();
					boolean boo =proOp.updateStudent(pro.proId, pro.proNum);
					if(boo) {
						System.out.println("修改成功！");
					}
					break;
				}
			}
		}while(number!=3);//字符串判断是否相等使用equals
		System.out.println("程序结束！")		           
		}   
}

运行结果如下：