c#如何比较替换成列表<class>从另一个</class>

Question

I have little problem checking and storing new data from an old one. I have a class structured like this:

public class class1
{
    public List<Class2> class2List {get,set}
    ...
}
public class class2
    {
        public Class3 class3 {get,set}
        ...
    }
public class class3
    {
        public string name {get,set}
        public int index {get,set}
        ...
    }

I want to create a method that will take a class 2 input and check if indexes are the same as old class1, if yes i want to store it. I try to do sme linQ to solve my problem but I am not an expert and I am a little stuck...

public static void SaveNewDataOnlyIfSameIndex(class1 workingData, List<class2> newdata)
    {
        List<class3> LocalWorkingDataClass3 = new List<class3>();
        foreach(class2 item in workingData.class2)
            {
                LocalWorkingDataClass3.add(item.class3);
            }
        List<int> LocalWorkingDataIndex = new List<int>();
        foreach(class3 item2 in LocalWorkingDataClass3 )
            {
                LocalWorkingDataIndex.add(item2.index);
            }
        List<class3> LocalEqualClasstoReplace = new List<class3>();
        LocalEqualClasstoReplace = newdata.Where(File => LocalWorkingDataIndex.Equals(File.Index));
    }

Answer 1

i can't understand very well what you need, but you can try to do something like this, using Linq:

public static void SaveNewDataOnlyIfSameIndex(Class1 WorkingData, List<Class2> Newdata)
{
    List<int> LocalWorkingDataClass3Index = WorkingData.Class2List.Select(i => i.Class3.Index).ToList()
 
    List<Class3> LocalEqualClasstoReplace = new List<Class3>();
    LocalEqualClasstoReplace = newdata.Where(f => LocalWorkingDataClass3Index.Contains(f.Class3.Index));
}

Answer 2

Hi. First of all, I am not sure that i got your question.

    public class Class1
    {
        public List<Class2> class2List {get;set;}
    }
    public class Class2
    {
       public string name {get;set;}
       public int index {get;set;}
    }

    public void CompareAndReplace(ref Class1 orginalDataList, Class2 newData){
       var check=orginalDataList.class2List.FirstOrDefault(g=>g.index==newData.index);
       if(check!=null){
         check.name=newData.name;
       }
    }

   //example to use assuming to "orginalDataList" has some datas..
   
    CompareAndReplace(ref orginalDataList,new Class2{index=1,name="Hello"});