Java

Question

我想问一下，因为我在这方面还很陌生，这是制作文档对象深层副本的正确方法吗，我不知道我是否正确地实现了字段复制。

package model;

public class Document implements Cloneable {
    //fields
    private String author;
    private String date;
    private double versionID;
    private String contents;


    public Document(String author,String date,double versionID,String contents) {
         this.author=author;
         this.date=date;
         this.versionID=versionID;
         this.contents=contents;        
    }

    //getters-setters

    }
    //making the deep-copy clone all obj ref to Document
    @Override
    public Object clone() throws CloneNotSupportedException {
        Document doc =(Document)super.clone();
        doc.author=this.author;
        doc.date=this.date;
        doc.versionID=this.versionID;
        doc.contents=this.contents;

        return doc;
    }   

}

Answer 1

你的对象只有原始类型和不可变字符串，所以 Document doc =(Document)super.clone(); 就足够了，你不必单独赋值。但这有点冒险，因为如果您向字段中添加一个可变对象，那么不单独复制该对象会导致问题。已经有关于使用一些现有库进行深度复制的扩展讨论，例如：How do you make a deep copy of an object in Java?

Java - 原型，深拷贝

Java - Prototype , making a deep copy

prototype

deep-copy