C＃对象列表

Question

I'm not sure how to create a list of objects. I get "Non-invocable member ListObjects.TestObject.UniqueID' cannot be used like a method."

Any insight would be helpful.

The code for the object I'm trying to create a list of:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ListObjects
{
    class TestObject
    {
        public int UniqueID { get; set; }


    }
}

Main code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ListObjects
{
    class Program
    {
        static void Main(string[] args)
        {
            TestObject TestObject = new TestObject();
            List<TestObject> ObjectList = new List<TestObject>();

            ObjectList.Add(new TestObject().UniqueID(1));
            ObjectList.Add(new TestObject().UniqueID(10));
            ObjectList.Add(new TestObject().UniqueID(39));

        }
    }
}

Answer 1

public int UniqueID { get; set; } is not a method its a setter and you use it like a method

do this

ObjectList.Add(new TestObject()
{
    UniqueID = 1
});

Answer 2

I cannot rememer the syntax but it is from memory:

repalce this line:

ObjectList.Add(new TestObject().UniqueID(1));

with this line:

ObjectList.Add(new TestObject(){UniqueID = 1});

and do the same for all .Add lines you have.

Answer 3

You are using UniqueId like a method. It is a property and must be assigned. If you know you'll be assigning an ID when creating a TestObject, you should make the constructor support that, and use it accordingly. If not, use ObjectList.Add(new TestObject { UniqueID = 1 }); to assign the value without a constructor.

This is how I would handle the situation:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ListObjects
{
    class TestObject
    {
        public int UniqueID { get; set; }

        public TestObject(int uniqueId)
        {
            UniqueID = uniqueId;    
        }
    }
}

Main code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ListObjects
{
    class Program
    {
        static void Main(string[] args)
        {
            List<TestObject> ObjectList = new List<TestObject>();

            ObjectList.Add(new TestObject(1));
            ObjectList.Add(new TestObject(10));
            ObjectList.Add(new TestObject(39));

        }
    }
}

Answer 4

There's a couple of things going on here. You don't need an instance of the object to declare the list, just the type.

Also, UniqueID is a property, not a method. You assign values to them (or read values from them), you don't pass in values like a parameter for a method.

You can also initialize the list in one call, like this:

List<TestObject> ObjectList = new List<TestObject>() 
                 { new TestObject() { UniqueID = 1}, 
                   new TestObject() { UniqueID = 10 },
                   new TestObject() { UniqueID = 39 } };

This will result in a new List<T> where T is of type TestObject , and the list is initialized to 3 instances of TestObject , with each instance initialized with a value for UniqueID .

Answer 5

 TestObject TestObject = new TestObject();

Remove this line.

And edit following lines to this syntax

new TestObject { UniqueID = 39 }