[英]Exception while removing a view from a LinearLayout in Android
我試圖在將自定義視圖從 LinearLayout 容器中刪除之前對其進行動畫處理。 只有我不斷收到一個 NullPointerException ,我無法追蹤到任何特定的地方。
當我添加了兩個視圖並刪除了第一個視圖時,就會發生異常。
我的代碼是:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.form_alg);
fadeInAnimation = AnimationUtils.loadAnimation(getApplicationContext(),
R.anim.witness_fade_in);
list = (LinearLayout) this.findViewById(R.id.alg_list_getuigen);
addWitness = (ImageButton) this
.findViewById(R.id.alg_getuige_toevoegen);
addWitness.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
final View w = View.inflate(getApplicationContext(),
R.layout.form_getuige, null);
ImageButton button = (ImageButton) w
.findViewById(R.id.getuige_verwijderen);
button.setOnClickListener(new android.view.View.OnClickListener() {
@Override
public void onClick(View v) {
Log.d(TAG, "deleteView");
Animation fadeOutAnimation = AnimationUtils
.loadAnimation(getApplicationContext(),
R.anim.witness_fade_out);
fadeOutAnimation
.setAnimationListener(new AnimationListener() {
@Override
public void onAnimationEnd(
Animation animation) {
list.removeView(w);
list.invalidate();
}
@Override
public void onAnimationRepeat(
Animation animation) {
}
@Override
public void onAnimationStart(
Animation animation) {
}
});
w.setVisibility(View.VISIBLE);
w.startAnimation(fadeOutAnimation);
w.setVisibility(View.INVISIBLE);
}
});
Log.d(TAG, "addView");
w.setVisibility(View.INVISIBLE);
list.addView(w);
w.startAnimation(fadeInAnimation);
w.setVisibility(View.VISIBLE);
list.invalidate();
}
});
}
這是堆棧跟蹤:
07-03 03:17:30.335: WARN/dalvikvm(343): threadid=1: thread exiting with uncaught exception (group=0x40015560)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): FATAL EXCEPTION: main
07-03 03:17:30.365: ERROR/AndroidRuntime(343): java.lang.NullPointerException
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1372)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.view.ViewGroup.drawChild(ViewGroup.java:1644)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.view.View.draw(View.java:6986)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.widget.FrameLayout.draw(FrameLayout.java:357)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.widget.ScrollView.draw(ScrollView.java:1409)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.view.ViewGroup.drawChild(ViewGroup.java:1646)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.view.ViewGroup.drawChild(ViewGroup.java:1644)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.view.View.draw(View.java:6883)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.widget.FrameLayout.draw(FrameLayout.java:357)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.view.ViewGroup.drawChild(ViewGroup.java:1646)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.view.ViewGroup.drawChild(ViewGroup.java:1644)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.view.View.draw(View.java:6883)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.widget.FrameLayout.draw(FrameLayout.java:357)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at com.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:1862)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.view.ViewRoot.draw(ViewRoot.java:1522)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.view.ViewRoot.performTraversals(ViewRoot.java:1258)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.view.ViewRoot.handleMessage(ViewRoot.java:1859)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.os.Handler.dispatchMessage(Handler.java:99)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.os.Looper.loop(Looper.java:123)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at android.app.ActivityThread.main(ActivityThread.java:3683)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at java.lang.reflect.Method.invokeNative(Native Method)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at java.lang.reflect.Method.invoke(Method.java:507)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
07-03 03:17:30.365: ERROR/AndroidRuntime(343): at dalvik.system.NativeStart.main(Native Method)
我有同樣的問題。 您必須使用 Handler 來執行修改 UI 的代碼(在本例中為 removeView())。 我會添加一個 Handler 字段並在您的 onCreate() 方法中構造它。 然后,在 onAnimationEnd() 中,執行以下操作:
fHandler.post(new Runnable() {
@Override
public void run() {
list.removeView(w);
list.invalidate();
}
}
要刪除布局的所有子級,然后添加新的子級,請找到以下代碼
if (linearLayout.getChildCount() > 0)
{
linearLayout.removeAllViewsInLayout();
linearLayout.invalidate();
}
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