有时候我们在给ImageButton加载背景图片的时候，会出现下面的异常：
1 org.xmlpull.v1.XmlPullParserException: Binary XML file line #3: <item> tag requires a 'drawable' attribute or child tag defining a drawable 2 at android.graphics.drawable.StateListDrawable.inflate(StateListDrawable.java:178) 3 at android.graphics.drawable.Drawable.createFromXmlInner(Drawable.java:867) 4 at android.graphics.drawable.Drawable.createFromXml(Drawable.java:804) 5 at com.android.layoutlib.bridge.impl.ResourceHelper.getDrawable(ResourceHelper.java:208) 6 at android.content.res.BridgeTypedArray.getDrawable(BridgeTypedArray.java:774) 7 at android.widget.ImageView.<init>(ImageView.java:119) 8 at android.widget.ImageButton.<init>(ImageButton.java:85) 9 at android.widget.ImageButton.<init>(ImageButton.java:81) 10 at sun.reflect.GeneratedConstructorAccessor23.newInstance(Unknown Source) 11 at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) 12 at java.lang.reflect.Constructor.newInstance(Unknown Source) 13 at android.view.LayoutInflater.createView(LayoutInflater.java:586) 14 at android.view.BridgeInflater.onCreateView(BridgeInflater.java:86) 15 at android.view.LayoutInflater.onCreateView(LayoutInflater.java:653) 16 at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:678) 17 at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:131) 18 at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:739) 19 at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64) 20 at android.view.LayoutInflater.rInflate(LayoutInflater.java:711) 21 at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:742) 22 at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64) 23 at android.view.LayoutInflater.rInflate(LayoutInflater.java:711) 24 at android.view.LayoutInflater.inflate(LayoutInflater.java:489) 25 at android.view.LayoutInflater.inflate(LayoutInflater.java:372) 26 ......
之所以会出现上面的异常，一般是在我们想给ImageButton动态加载图片，而用xml文件来设置切换按钮的背景。但是这种异常不影响程序运行，碰到这种异常有两个解决方法：
1.直接重启Eclipse，再打开布局文件就不会出项异常了。
2.如果你用的是纯颜色的背景，不是图片，那你不能直接在xml文件直接填写颜色值，需要values文件夹中color.xml（或是drawable.xml）设置颜色值，然后使用即可。