如何将值从一个 Java 类复制到具有相同属性的另一个类

Question

这是我的类结构：（省略了 getter 和 setter）public class A {     public List<QuestionTemplate> qTemplateList;}public class QuestionTemplate {    public List<QuestionList> qList;}public class QuestionList {    public String questionText;    public String questionChoice;}----------------------------------------------------public class B {     public List<QuestionTemplate> qTemplateList;}public class QuestionTemplate {    public List<QuestionList> qList;}public class QuestionList {    public String questionText;    public String questionChoice;} 我想手动将数据从 B 类复制到 A 类，手动复制字段而不是使用任何类型的映射器。我尝试遍历列表并尝试从一个列表复制到另一个列表（从最内部的列表开始但遇到了很多问题。请原谅我是新手。我试过了。请帮忙。

Answer 1

此代码需要 Java 7 或更高版本。

选项 A 通过迭代手动复制数据：

    A a = new A();

    ..

    List<QuestionTemplate> templateListCopy = new LinkedList<>();

    for (QuestionTemplate template : a.qTemplateList) {

        List<QuestionList> questionListCopy = new LinkedList<>();

        for (QuestionList question : template.qList) {

            QuestionList questionCopy = new QuestionList();

            questionCopy.questionText = question.questionText;

            questionCopy.questionChoice = question.questionChoice;

            questionListCopy.add(questionCopy);

        }

        QuestionTemplate questionTemplateCopy = new QuestionTemplate();

        questionTemplateCopy.qList = questionListCopy;

        templateListCopy.add(questionTemplateCopy);

    }

    B b = new B();

    b.qTemplateList = templateListCopy;

选项 B 修改类并添加复制方法，使实现代码不那么混乱：

class A {

    public List<QuestionTemplate> qTemplateList;

    public A copy() {

        A copy = new A();

        List<QuestionTemplate> questionTemplateListCopy = new ArrayList<>(qTemplateList.size());

        for (QuestionTemplate questionTemplate : qTemplateList) {

            questionTemplateListCopy.add(questionTemplate.copy());

        }

        copy.qTemplateList = questionTemplateListCopy;

        return copy;

    }

}

class QuestionTemplate {

    public List<QuestionList> qList;

    public QuestionTemplate copy() {

        QuestionTemplate copy = new QuestionTemplate();

        List<QuestionList> qListCopy = new ArrayList<>(qList.size());

        for (QuestionList questionList : qList) {

            qListCopy.add(questionList.copy());

        }

        copy.qList = qListCopy;

        return copy;

    }

}

class QuestionList {

    public String questionText;

    public String questionChoice;

    public QuestionList copy() {

        QuestionList copy = new QuestionList();

        copy.questionText = questionText;

        copy.questionChoice = questionChoice;

        return copy;

    }

}

执行：

A a = new A();

..

B b = new B();

b.qTemplateList = a.copy().qTemplateList;

Answer 2

请参考此 通过反射将一个类中的字段的所有值复制到另一个类

那里已经回答了类似的问题。