Image view with long press hint

HintedImageButton.java

package in.lib.view;

import android.content.Context;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.View;
import android.view.View.OnLongClickListener;
import android.widget.ImageView;
import android.widget.Toast;

/**
 * Extended image view to show the content description in a Toast view when
 * the user long presses.
 *
 * Note: `android:contentDescription` must be set in order for the toast to
 * work
 *
 * @author Callum Taylor <http://callumtaylor.net>
 */
public class HintedImageButton extends ImageButton implements OnLongClickListener
{
	private OnLongClickListener mOnLongClickListener;

	public HintedImageButton(Context context)
	{
		super(context);

		setOnLongClickListener(this);
	}

	public HintedImageButton(Context context, AttributeSet attrs)
	{
		super(context, attrs);

		setOnLongClickListener(this);
	}

	@Override public void setOnLongClickListener(OnLongClickListener l)
	{
		if (l == this)
		{
			super.setOnLongClickListener(l);
			return;
		}

		mOnLongClickListener = l;
	}

	@Override public boolean onLongClick(View v)
	{
		if (mOnLongClickListener != null)
		{
			if (!mOnLongClickListener.onLongClick(v))
			{
				handleLongClick();
				return true;
			}
		}
		else
		{
			handleLongClick();
			return true;
		}

		return false;
	}

	private void handleLongClick()
	{
		String contentDesc = getContentDescription().toString();
		if (!TextUtils.isEmpty(contentDesc))
		{
			int[] pos = new int[2];
			getLocationInWindow(pos);

			Toast t = Toast.makeText(getContext(), contentDesc, Toast.LENGTH_LONG);
			t.setGravity(Gravity.TOP | Gravity.LEFT, pos[0] - ((contentDesc.length() / 2) * 12), pos[1] - 128);
			t.show();
		}
	}
}

i have just started using android studio and in which activity should i paste this code ?
plz reply ASAP

in this line Toast t = Toast.makeText(getContext(), contentDesc, 1200); shouldn't 1200 replaced with Toast.LENGTH_LONG
or Toast.LENGTH_SHORT instead?