這是我的類結構：（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;} 我想手動將數據從 B 類復制到 A 類，手動復制字段而不是使用任何類型的映射器。我嘗試遍歷列表并嘗試從一個列表復制到另一個列表（從最內部的列表開始但遇到了很多問題。請原諒我是新手。我試過了。請幫忙。
1 回答
三國紛爭
TA貢獻1804條經驗 獲得超7個贊
此代碼需要 Java 7 或更高版本。
選項 A 通過迭代手動復制數據：
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;
選項 B 修改類并添加復制方法，使實現代碼不那么混亂：
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;
}
}
執行：
A a = new A();
..
B b = new B();
b.qTemplateList = a.copy().qTemplateList;
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