使用Lombok创建指定字段构造器遇报错：如何生成仅两字段构造器？

Got it, let's break down how to generate a constructor for exactly two fields in your Category class while using Lombok, and fix that visibility error you're seeing.

First, Understand the Root of the Error #

That "not visible" message usually boils down to one of two issues:

• The two-parameter constructor you're trying to use doesn't exist at all (Lombok didn't generate it as you expected)
• The constructor does exist, but it's marked as private or package-private, so your App.java can't access it

Solution 1: Manually Write the Constructor (Simplest & Most Predictable) #

Lombok plays perfectly nice with manually written code—you don't have to rely solely on annotations. If you only need a constructor for two specific fields, just write it out directly alongside your Lombok annotations:

import lombok.Data;
import java.util.List;

@Data // Generates getters, setters, toString, equals/hashCode, and a no-arg constructor
public class Category {
    // Fields you want in the constructor
    private String name;
    private String description;
    
    // Other fields
    private Long id;
    private List<Product> products;

    // Your custom two-field constructor
    public Category(String name, String description) {
        this.name = name;
        this.description = description;
    }
}

This works flawlessly—Lombok won't overwrite or conflict with your manual constructor. You can now call new Category("Books", "Fiction and non-fiction") in App.java without any visibility issues.

Solution 2: Use Lombok's @RequiredArgsConstructor (Auto-Generate the Constructor) #

If you prefer to let Lombok handle constructor generation, use @RequiredArgsConstructor along with either final or @NonNull on the fields you want included. Lombok will automatically create a public constructor for all fields marked this way:

import lombok.Data;
import lombok.NonNull;
import lombok.RequiredArgsConstructor;
import java.util.List;

@Data
@RequiredArgsConstructor // Generates constructor for @NonNull/final fields
public class Category {
    // Mark fields to include with @NonNull
    @NonNull
    private String name;
    @NonNull
    private String description;
    
    // Other fields (not included in constructor)
    private Long id;
    private List<Product> products;
}

Or if you prefer using final instead of @NonNull:

import lombok.Data;
import lombok.RequiredArgsConstructor;
import java.util.List;

@Data
@RequiredArgsConstructor
public class Category {
    private final String name;
    private final String description;
    
    private Long id;
    private List<Product> products;
}

Both approaches will generate a public Category(String, String) constructor that your App.java can access freely.

How to Avoid the Visibility Trap #

If you still get the "not visible" error after trying these, double-check:

• You didn't set the access parameter on @RequiredArgsConstructor to something restrictive like AccessLevel.PRIVATE (the default is AccessLevel.PUBLIC, which is what you want)
• You're not mixing conflicting annotations (e.g., @NoArgsConstructor alone won't generate your two-arg constructor—you need to add the custom constructor or @RequiredArgsConstructor)

内容的提问来源于stack exchange，提问作者Jeff Cook