java - 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(从最里面的列表开始，但遇到了很多问题。请原谅，因为我是新手。我尝试过。请帮助。

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，以使实现代码更容易混淆:

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;
    }
}

实现:

A a = new A();

..

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