用java编写以下内容 生产制造企业开发一个零部件的库存管理系统。目前企业生产两种产品:零部件(part) 和组件 (asscembly)。 (1) 定义零部件类， (2) 增加目录类，属性包括: 零部件编号、零部件名称及零部件价格;

以下是Java代码实现：

零部件类：

public class Part {
    private int partNumber;
    private String partName;
    private double partPrice;

    public Part(int partNumber, String partName, double partPrice) {
        this.partNumber = partNumber;
        this.partName = partName;
        this.partPrice = partPrice;
    }

    public int getPartNumber() {
        return partNumber;
    }

    public void setPartNumber(int partNumber) {
        this.partNumber = partNumber;
    }

    public String getPartName() {
        return partName;
    }

    public void setPartName(String partName) {
        this.partName = partName;
    }

    public double getPartPrice() {
        return partPrice;
    }

    public void setPartPrice(double partPrice) {
        this.partPrice = partPrice;
    }
}

目录类：

import java.util.ArrayList;
import java.util.List;

public class Catalog {
    private List<Part> parts = new ArrayList<>();

    public void addPart(Part part) {
        parts.add(part);
    }

    public Part findPart(int partNumber) {
        for (Part part : parts) {
            if (part.getPartNumber() == partNumber) {
                return part;
            }
        }
        return null;
    }
}

使用示例：

public class Main {
    public static void main(String[] args) {
        Catalog catalog = new Catalog();

        Part part1 = new Part(1, "part1", 10.0);
        Part part2 = new Part(2, "part2", 20.0);
        Part part3 = new Part(3, "part3", 30.0);

        catalog.addPart(part1);
        catalog.addPart(part2);
        catalog.addPart(part3);

        Part foundPart = catalog.findPart(2);
        if (foundPart != null) {
            System.out.println("Part found: " + foundPart.getPartName());
        } else {
            System.out.println("Part not found");
        }
    }
}

输出结果：

Part found: part2