NullPointerException in Drawable mutate method of Android 1.6

, Android 1.6 . Android 1.6, :

android.graphics.drawable.StateListDrawable.java:
...
public Drawable mutate() {
    if (!mMutated && super.mutate() == this) {
        final int[][] sets = mStateListState.mStateSets;
        final int count = sets.length;
        mStateListState.mStateSets = new int[count][];
        for (int i = 0; i < count; i++) {
            mStateListState.mStateSets[i] = sets[i].clone(); //NPE causing line
        }
        mMutated = true;
    }
    return this;
}
...

mStateListState.mStateSets[i] = sets[i].clone(); //NPE causing line

clone() NullPointerException

Android > 1.6 :

public Drawable mutate() {
        if (!mMutated && super.mutate() == this) {
            final int[][] sets = mStateListState.mStateSets;
            final int count = sets.length;
            mStateListState.mStateSets = new int[count][];
            for (int i = 0; i < count; i++) {
                final int[] set = sets[i];
                if (set != null) {
                    mStateListState.mStateSets[i] = set.clone();
                }
            }
            mMutated = true;
        }
        return this;
    }

Android 1.6 . , mStateSets [i] :

android.graphics.drawable.DrawableContainer.DrowableContainerState:
... 
public final int addChild(Drawable dr) {
        final int pos = mNumChildren;

        if (pos >= mDrawables.length) {
            growArray(pos, pos+10); //Interesting line
        }

        dr.setVisible(false, true);
        dr.setCallback(mOwner);

        mDrawables[pos] = dr;
        mNumChildren++;
        mChildrenChangingConfigurations |= dr.getChangingConfigurations();
        mHaveOpacity = false;
        mHaveStateful = false;

        mConstantPadding = null;
        mPaddingChecked = false;
        mComputedConstantSize = false;

        return pos;
    }
...

xml. , mStateListState.mStateSets N * 10.

list_selector_background.xml, , android.R.drawable.list_selector_background:

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright (C) 2008 The Android Open Source Project

     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.
     You may obtain a copy of the License at

          http://www.apache.org/licenses/LICENSE-2.0

     Unless required by applicable law or agreed to in writing, software
     distributed under the License is distributed on an "AS IS" BASIS,
     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     See the License for the specific language governing permissions and
     limitations under the License.
-->

<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <item android:state_window_focused="false"
        android:drawable="@color/transparent" />

    <!-- Even though these two point to the same resource, have two states so the drawable will invalidate itself when coming out of pressed state. -->
    <item android:state_focused="true" android:state_enabled="false"
        android:state_pressed="true"
        android:drawable="@drawable/list_selector_background_disabled" />
    <item android:state_focused="true" android:state_enabled="false"
        android:drawable="@drawable/list_selector_background_disabled" />

    <item android:state_focused="true" android:state_pressed="true"
        android:drawable="@drawable/list_selector_background_transition" />
    <item android:state_focused="false" android:state_pressed="true"
        android:drawable="@drawable/list_selector_background_transition" />

    <item android:state_focused="true"
        android:drawable="@drawable/list_selector_background_focus" />

</selector>

6 ! , ? 1. list_selector_background.xml {Project}/res/drowable/ Android one :

<item android:state_window_focused="false"
    android:drawable="@color/transparent" />

<item android:state_window_focused="false" android:drawable="@android:color/transparent" />

• Android :

  list_selector_background_disabled.9.png list_selector_background_focus.9.png list_selector_background_longpress.9.png list_selector_background_pressed.9.png list_selector_background_transition.xml

• list_selector_background.xml, , (6 + 4 = 10):

  <item android:animationCache="true"
      android:drawable="@android:color/transparent" />
  
  <item android:animationCache="false"
      android:drawable="@android:color/transparent" />
  
  <item android:alwaysDrawnWithCache="false"
      android:drawable="@android:color/transparent" />
  
  <item android:alwaysDrawnWithCache="true"
      android:drawable="@android:color/transparent" />
  

. . .