Adding multiple objects to an ArrayList results in only the last item being added multiple times

Question

I'm trying to add objects to an ArrayList, but it seems that whenever I call the add method, the list is populated by only the last object that I add.

Here's how I add:

MyObject testObject1 = new MyObject();
testObject1.setType(0);
MyList.myList.add(testObject1);
MyObject testObject2 = new MyObject();
testObject2.setType(1);
MyList.myList.add(testObject2);

MyList is a class with a single ArrayList which is defined as follows:

public static ArrayList<MyObject> myList = new ArrayList<MyObject>();

MyObject is a class with some member variables and methods:

static int type;
public void setType(int inType) {
  type = inType;
}

I then list out the objects in MyList.myList as follows:

for (int i=0; i<MyList.myList.size(); i++) {
  Log.d(TAG, "Type is " + MyList.myList.get(i).getType());
}

It lists 2 objects, but the type is always 1.

What's up?

Thanks.

Jigar Joshi · Accepted Answer · 2014-06-24 06:59:18Z

3

because setType is static, which isn't associated with Object's state

MyObject.setType = 1;

remove static keyword from setType 's delcaration in MyObject class and set its value per instance

See

class member variable

answered Jun 24, 2014 at 6:59

Jigar Joshi

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4 Comments

user1118764 Over a year ago

Hi, I made a typo in the original posted code. I didn't actually call MyObject.setType(), but called the instance's setType instead, i.e. testObject1.setType(0) and testObject2.setType(1)

Jigar Joshi Over a year ago

post your setType method full body

user1118764 Over a year ago

Done. It's in the MyObject class.

Jigar Joshi Over a year ago

its the same thing you are assigning value to static variable, which is not per object but per class loaded, so all the instances share values, please re read my answer

vinayknl · Accepted Answer · 2014-06-24 07:52:00Z

0

static int type;
public void setType(int inType) {
  type = inType;
}

You should not be setting a static variable from an instance method.

int type;
public void setType(int inType) {
  type = inType;
}

Changing as above will fix your issue.

edited Jun 24, 2014 at 7:52

answered Jun 24, 2014 at 7:45

vinayknl

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