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POListView does not display with custom adapter class
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  1. POListView does not display with custom adapter class
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    copied!<p>I have an <code>Apple</code> class with two fields, <code>colour</code> and <code>rotation</code>, and an <code>AppleView</code> View which draws the apple in that colour and rotation in its <code>onDraw</code> method (this is a simplification of my actual code). The AppleView has a default apple (let's say, red and rotated by 0 degrees) which can be reassigned. Here is some pseudocode for the two classes:</p> <pre><code>public class Apple { int colour; int rotation; } public class AppleView extends View { Apple apple = getDefaultApple(); @Override protected void onDraw(Canvas canvas) { drawApple(canvas, apple); } } </code></pre> <p>I'd like to make a ListView of AppleViews from an ArrayList of apples. I create two layouts: a ListView (<code>R.layout.list_view</code>):</p> <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt; &lt;ListView xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:id="@android:id/list"&gt; &lt;/ListView&gt; </code></pre> <p>and a list item, which is just an <code>AppleView</code> (<code>R.layout.list_item</code>):</p> <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt; &lt;com.mypackage.AppleView xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/apple"&gt; &lt;/com.mypackage.AppleView&gt; </code></pre> <p>Finally, I extend <code>ListActivity</code> and use a custom adapter class to draw the list items:</p> <pre><code>public class MyListActivity extends ListActivity { ArrayList&lt;Apple&gt; apples = new ArrayList&lt;Apple&gt;(); public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.list_view); // Add 100 random apples to the list for demonstration. for (int i = 0; i &lt; 100; i++) { apples.add(getRandomApple()); } getListView().setAdapter(new MyAdapter(this, R.layout.list_item, apples)); } class MyAdapter extends ArrayAdapter&lt;Apple&gt; { public MyAdapter(Context context, int resourceID, ArrayList&lt;Apple&gt; items) { super(context, resourceID, items); } @Override public View getView(int position, View convertView, ViewGroup parent) { if (convertView == null) { convertView = getLayoutInflater().inflate(R.layout.list_item, parent, false); } // Change this AppleView's apple to the new ArrayList element at this position. AppleView appleView = (AppleView) convertView.findViewById(R.id.apple); appleView.apple = apples.get(position); return convertView; } } } </code></pre> <p>Although all the right methods are being called (i.e. getView and onDraw for each apple), the ListView does not display:</p> <p><img src="https://i.stack.imgur.com/2j6NP.png" alt="enter image description here"></p> <p>Where is the error in the above code? </p>
 

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