ListView doesn't show adapter

With this piece of code

            final ListView lw   =   (ListView) findViewById( R.id.book_list );
        lw.setVisibility(View.VISIBLE);

        ListView listBookView   =   (ListView) findViewById( R.id.book_list );
        ArrayList<HashMap<String, Object>> my_list  = new ArrayList<HashMap<String, Object>>();

        for ( int x=0; x< book_list.size(); x++)
        {
            String[] valori_book    =   book_list.get( x ).getObjVars();
            HashMap<String, Object> map = new HashMap<String, Object>();
            map.put("book", valori_book[ 0 ]);
            map.put("descr", valori_book[ 1 ] );

            my_list.add(map);
        }
        // ...
        SimpleAdapter showMenu = new SimpleAdapter(this, my_list, R.layout.activity_book_booklistmask,
                    new String[] { "book" , "descr" }, new int[] {R.id.nome_quaderno, R.id.descrizione_quaderno});
        listBookView.setAdapter(showMenu);

java.lang.IllegalStateException: android.widget.ListView is not a view that can be bounds by this SimpleAdapter

The logcat does开发者_运维问答n't write the error's row of my project so i don't know where check :/

E/AndroidRuntime(  904): java.lang.IllegalStateException: android.widget.ListView is not a  view that can be bounds by this SimpleAdapter
E/AndroidRuntime(  904):        at android.widget.SimpleAdapter.bindView(SimpleAdapter.java:195)
E/AndroidRuntime(  904):        at android.widget.SimpleAdapter.createViewFromResource(SimpleAdapter.java:126)
E/AndroidRuntime(  904):        at android.widget.SimpleAdapter.getView(SimpleAdapter.java:114)
E/AndroidRuntime(  904):        at android.widget.AbsListView.obtainView(AbsListView.java:1315)
E/AndroidRuntime(  904):        at android.widget.ListView.makeAndAddView(ListView.java:1727)
E/AndroidRuntime(  904):        at android.widget.ListView.fillDown(ListView.java:652)
E/AndroidRuntime(  904):        at android.widget.ListView.fillFromTop(ListView.java:709)
E/AndroidRuntime(  904):        at android.widget.ListView.layoutChildren(ListView.java:1580)
E/AndroidRuntime(  904):        at android.widget.AbsListView.onLayout(AbsListView.java:1147)
E/AndroidRuntime(  904):        at android.view.View.layout(View.java:7035)
E/AndroidRuntime(  904):        at android.widget.RelativeLayout.onLayout(RelativeLayout.java:909)
E/AndroidRuntime(  904):        at android.view.View.layout(View.java:7035)
E/AndroidRuntime(  904):        at android.widget.FrameLayout.onLayout(FrameLayout.java:333)
E/AndroidRuntime(  904):        at android.view.View.layout(View.java:7035)
E/AndroidRuntime(  904):        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1249)
E/AndroidRuntime(  904):        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1125)
E/AndroidRuntime(  904):        at android.widget.LinearLayout.onLayout(LinearLayout.java:1042)
E/AndroidRuntime(  904):        at android.view.View.layout(View.java:7035)
E/AndroidRuntime(  904):        at android.widget.FrameLayout.onLayout(FrameLayout.java:333)
E/AndroidRuntime(  904):        at android.view.View.layout(View.java:7035)
E/AndroidRuntime(  904):        at android.view.ViewRoot.performTraversals(ViewRoot.java:1045)
E/AndroidRuntime(  904):        at android.view.ViewRoot.handleMessage(ViewRoot.java:1727)
E/AndroidRuntime(  904):        at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(  904):        at android.os.Looper.loop(Looper.java:123)
E/AndroidRuntime(  904):        at android.app.ActivityThread.main(ActivityThread.java:4627)
E/AndroidRuntime(  904):        at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(  904):        at java.lang.reflect.Method.invoke(Method.java:521)
E/AndroidRuntime(  904):        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
E/AndroidRuntime(  904):        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
E/AndroidRuntime(  904):        at dalvik.system.NativeStart.main(Native Method)

From the SimpleAdapter documentation

A view that implements Checkable (e.g. CheckBox). The expected bind value is a boolean.

TextView. The expected bind value is a string and setViewText(TextView, String) is invoked.

ImageView. The expected bind value is a resource id or a string and setViewImage(ImageView, int) or setViewImage(ImageView, String) is invoked.

It would appear that passing an Object as the mapped object is not compatible with SimpleAdapter. Change the object type, or create a custom adapter (I recommend the later)