C＃如何使用另一个集合中的对象替换一个集合中的对象

Question

How do I replace objects in Collection1 with a matching object(by name and description) from Collection2?

Also the objects for the matching operation in Collection2 have to be within a certain range, say from 0-20. Objects with index > 20 in Collection2 need to be appended to Collection1.

Answer 1

    List<MyClass> mainList = new List<MyClass>();
    List<MyClass> childList = new List<MyClass>();

    foreach (MyClass myClass in childList)
    {
        int index = mainList.FindIndex(delegate(MyClass item) { return    (item.Name==myClass.Name && ; item.Description == myClass.Description);});
        mainList[index] = myClass;
    }

Try this one. I hope you get your desire result.

Answer 2

List<MyClass> originalCollection = new List<MyClass>();
List<MyClass> newStuff = new List<MyClass>();

foreach (var item in newStuff)
{
    int index = originalCollection.FindIndex(x => x.Name == item.Name && x.Description == item.Description);

    if (index < 0)
        continue;

    originalCollection[index] = item;
}

If your really want a 1-liner...

List<MyClass> originalCollection = new List<MyClass>();
List<MyClass> newStuff = new List<MyClass>();

originalCollection = newStuff.Concat(originalCollection.Where(x => !newStuff.Any(y => y.Description == x.Description && y.Name == x.Name)).ToArray()).ToList();

Answer 3

This is one way:

foreach (var item in collection2.Take(20)) // grab replacement range
{
    int index;
    if ((index = collection1.FindIndex(x => 
                                  x.Name == item.Name && 
                                  x.Description == item.Description)) > -1)
    {
        collection1[index] = item;
    }
}
collection1.AddRange(collection2.Skip(20)); // append the rest

It's highly likely that the code can be improved even more, if your intentions were a little more clear. There may be a cleaner way if the problem was better understood.

Answer 4

One way in extension Method

public static void Replace(this object[] elements, object oldObject, object newObject) {
var index = elements.IndexOf(oldObject);

if (index > 0) {
 elements[index] = newObject;
}}