Ottenere ClassCastException quando si tenta di inserire RelativeLayout dianmicamente?

Question

 setContentView(R.layout.main2); 

     out= new ArrayList<TextView>(); 
     llay =(RelativeLayout) findViewById(R.id.displayPoll); 

     RelativeLayout.LayoutParams lparams = new RelativeLayout.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT); 
     RelativeLayout.LayoutParams lparams1 = new RelativeLayout.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT); 
     LayoutParams lpar = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT); 
     Log.v("my","rched"); 


     out.add(new TextView(this)); 
     out.get(0).setLayoutParams(lpar); 
     out.get(0).setId(1); 
     lparams1.addRule(RelativeLayout.ALIGN_BOTTOM,R.id.user_name); 
     llay.setLayoutParams(lparams1); 
     out.get(0).setText("Title "+0+"\n\n\n\n\n\n"); 
     my_poll.this.llay.addView(out.get(0)); 

      for (int i = 1; i < 3;i++)//mJsonArray.length(); i++) 
      { 
       out.add(new TextView(this)); 

       out.get(i).setLayoutParams(lpar); 
       out.get(i).setId(i+1); 
       Log.v("my","hey : "+out.get(i-1).getId()); 

       lparams.addRule(RelativeLayout.BELOW,out.get(i-1).getId()); 
       llay.setLayoutParams(lparams); 

       out.get(i).setText("Title "+i+"\n\n\n\n\n\n"); 

       llay.addView(out.get(i)); 

      } 

       Log.v("my","rasasched"); 

Eseguendo il programma sto ottenendo questo errore

04-06 20:30:49.372: E/AndroidRuntime(1093): FATAL EXCEPTION: main 
04-06 20:30:49.372: E/AndroidRuntime(1093): java.lang.ClassCastException: android.widget.RelativeLayout$LayoutParams 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at android.widget.ScrollView.onMeasure(ScrollView.java:301) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at android.view.View.measure(View.java:8171) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:245) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at android.view.View.measure(View.java:8171) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at android.widget.LinearLayout.measureVertical(LinearLayout.java:526) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at android.widget.LinearLayout.onMeasure(LinearLayout.java:304) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at android.view.View.measure(View.java:8171) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:3132) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at android.widget.FrameLayout.onMeasure(FrameLayout.java:245) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at android.view.View.measure(View.java:8171) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at android.view.ViewRoot.performTraversals(ViewRoot.java:801) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at android.view.ViewRoot.handleMessage(ViewRoot.java:1727) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at android.os.Handler.dispatchMessage(Handler.java:99) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at android.os.Looper.loop(Looper.java:123) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at android.app.ActivityThread.main(ActivityThread.java:4627) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at java.lang.reflect.Method.invokeNative(Native Method) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at java.lang.reflect.Method.invoke(Method.java:521) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at dalvik.system.NativeStart.main(Native Method) 

Questo è il im file XML utilizzando ..

<RelativeLayout 
android:id="@+id/displayPoll" 
android:layout_width="fill_parent" 
android:layout_height="fill_parent" 
android:background="@drawable/back_blue_grad" 
android:padding="0dp" > 


    <TextView 
    android:id="@+id/user_name" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_alignParentTop="true" 
    android:layout_centerHorizontal="true" 
    android:text="Priyank Bharad" 
    android:textColor="#fff" 
    android:textSize="28dp" 
    android:textStyle="bold" /> 
    <ImageView 
    android:id="@+id/p_image" 
    android:layout_width="35dp" 
    android:layout_height="35dp" 
    android:layout_marginRight="10dp" 
    android:src="@drawable/final_fb" 
    android:layout_toLeftOf="@id/user_name"/> 
</RelativeLayout> 

</ScrollView> 

Answer 1

L'errore qui è nella scelta della sottoclasse di LayoutParams.

La versione corretta del LayoutParams istanziare dipende dalla genitore della vista che si sta creando, non il tipo della vista stessa.

Date un'occhiata alla discarica logcat:

04-06 20:30:49.372: E/AndroidRuntime(1093): java.lang.ClassCastException: android.widget.RelativeLayout$LayoutParams 
04-06 20:30:49.372: E/AndroidRuntime(1093):  at android.widget.ScrollView.onMeasure(ScrollView.java:301) 

Android sta cercando di typecast l'istanza di RelativeLayout.LayoutParams a, ciò che credo dovrebbe essere ScrollView.LayoutParams, perché il vostro RelativeLayout si trova all'interno di un ScrollView.

La correzione dovrebbe essere quella di modificare il tipo di parametro di layout che si sta utilizzando su RelativeLayout su ScrollView.LayoutParams.