Android 尝试动态插入RelativeLayout时获取ClassCastException？
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Getting ClassCastException when trying to insert RelativeLayout dyanmically?
提问by Priyank Bharad
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");
By executing the program I am getting this error
通过执行程序，我收到此错误
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)
This is the XML file i m using..
这是我使用的 XML 文件..
<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>
回答by wsanville
The mistake here is in the choice of the subclass of LayoutParams.
这里的错误在于 的子类的选择LayoutParams。
The correct version of LayoutParamsto instantiate depends on the parentof the view you're creating, not the type of the view itself.
LayoutParams要实例化的正确版本取决于您正在创建的视图的父级，而不是视图本身的类型。
Take a look at the logcat dump:
看一下 logcat 转储：
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 is trying to typecast the instance of RelativeLayout.LayoutParamsto, what I believe should be ScrollView.LayoutParams, because your RelativeLayoutis inside of a ScrollView.
Android 正在尝试对 to 的实例进行类型转换RelativeLayout.LayoutParams，我认为应该是ScrollView.LayoutParams，因为您RelativeLayout在ScrollView.
The fix should be to change the layout params type that you're using on the RelativeLayoutto ScrollView.LayoutParams.
修复应该是更改您在RelativeLayoutto上使用的布局参数类型ScrollView.LayoutParams。
