我正在开发一个Android应用程序,该应用程序要求我定义主LinearLayouts
中包含的某些LinearLayout
,这些布局数据是通过run_time动态获取的,但是Container Layout是在XML中静态声明的,我添加了动态创建的布局到主布局,但是我得到了NullPointerException
:
02-13 11:03:45.745: WARN/System.err(620): java.lang.NullPointerException
02-13 11:03:45.745: WARN/System.err(620): at com.example.solaceap.Media.initiatePopupWindow(Media.java:476)
02-13 11:03:45.755: WARN/System.err(620): at android.view.View.performClick(View.java:3480)
02-13 11:03:45.765: WARN/System.err(620): at android.view.View$PerformClick.run(View.java:13983)
02-13 11:03:45.765: WARN/System.err(620): at android.os.Handler.handleCallback(Handler.java:605)
02-13 11:03:45.765: WARN/System.err(620): at android.os.Handler.dispatchMessage(Handler.java:92)
02-13 11:03:45.775: WARN/System.err(620): at android.os.Looper.loop(Looper.java:137)
02-13 11:03:45.785: WARN/System.err(620): at android.app.ActivityThread.main(ActivityThread.java:4340)
02-13 11:03:45.785: WARN/System.err(620): at java.lang.reflect.Method.invokeNative(Native Method)
02-13 11:03:45.795: WARN/System.err(620): at java.lang.reflect.Method.invoke(Method.java:511)
02-13 11:03:45.795: WARN/System.err(620): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
02-13 11:03:45.805: WARN/System.err(620): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
02-13 11:03:45.805: WARN/System.err(620): at dalvik.system.NativeStart.main(Native Method)
这是我的代码:
主要布局:
<LinearLayout
android:id="@+id/music_popup"
android:layout_width="300dp"
android:layout_height="500dp"
android:background="@drawable/ac_overlay"
android:gravity="top"
android:orientation="vertical"
android:paddingBottom="12dp"
android:paddingTop="12dp" >
</LinearLayout>
这是动态声明的布局:
private View layout = null;
LinearLayout music_pop_up = (LinearLayout) findViewById(R.id.music_popup);
private void initiatePopupWindow(String section) {
layout = inflater.inflate(R.layout.music_popup,
(ViewGroup) findViewById(R.id.music_pop));
// create a 300px width and 470px height PopupWindow
pw = new PopupWindow(layout,
ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT, true);
// display the popup in the center
pw.showAtLocation(layout, Gravity.CENTER, 0, 0);
music_cancel = (Button) layout.findViewById(R.id.back_music);
music_cancel.setOnClickListener(onCancelClick);
get_music_albums();
}
public void get_music_albums(){
int albums_num = albums_arr.size();
for(int i = 0; i < albums_num; i++){
LinearLayout music_layout = new LinearLayout(this);
music_layout.setOrientation(LinearLayout.HORIZONTAL);
music_layout.setLayoutParams(music_lp);
music_pop_up.addView(music_layout); // this is where i got the Exception
ImageButton poster = new ImageButton(this);
poster.setTag(i);
poster.setLayoutParams(album_lp);
music_layout.addView(poster);
poster.setClickable(true);
poster.setAdjustViewBounds(true);
poster.setScaleType(ScaleType.CENTER_INSIDE);
poster.setBackgroundColor(Color.TRANSPARENT);
poster.setImageResource(R.drawable.media_poster);
TextView album_name = new TextView(this);
album_name.setLayoutParams(album_name_lp);
music_layout.addView(album_name);
album_name.setTextSize(13);
album_name.setTextColor(Color.WHITE);
album_name.setText("test");
TextView artist_name = new TextView(this);
artist_name.setLayoutParams(artist_name_lp);
music_layout.addView(artist_name);
artist_name.setTextSize(8);
artist_name.setTextColor(Color.CYAN);
artist_name.setText("test");
}
}
}
这就是我声明布局参数的方式:
// Declaring the Music LayoutParams
music_lp = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, 50);
music_lp.gravity = Gravity.LEFT;
music_lp.setMargins(20, 0, 0, 0);
// Declaring the Album LayoutParams
album_lp = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT, 1);
album_lp.gravity = Gravity.CENTER;
album_lp.setMargins(3, 3, 3, 3);
// Declaring the Album_Name LayoutParams
album_name_lp = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
album_name_lp.gravity = Gravity.CENTER;
// Declaring the Artist_Name LayoutParams
artist_name_lp = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
artist_name_lp.gravity = Gravity.BOTTOM;
最佳答案
好像您没有正确构建视图,
initiatePopupWindow(Media.java:476)在第476行崩溃
如果您不知道线性布局的大小,请考虑使用listview并在那里回收视图。
如果您不能使用listview,请在此行调试您的类,并检查为什么它仍然为空。