我有这个代码albumsactivity扩展listactivity。我想要做的是启用单击imgClick图像，该图像设置为可点击列表中的项目以显示弹出菜单但我得到运行时异常nullpointerexception。请帮我解决这个问题
@SuppressLint({ "NewApi", "ViewHolder" })
public class AlbumsActivity extends ListActivity {
ConnectionDetector cd;
AlertDialogManager alert = new AlertDialogManager();
private ProgressDialog pDialog;
JSONParser jsonParser = new JSONParser();
ArrayList<HashMap<String, String>> albumsList;
JSONArray albums = null;
EditText inputSearch;
ImageView imgClick;
SimpleAdapter adapter = null;
private static final String URL_ALBUMS = "http://api.androidhive.info/songs/album.php";
// ALL JSON node names
private static final String TAG_ID = "id";
private static final String TAG_NAME = "name";
private static final String TAG_SONGS_COUNT = "songs_count";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_albums);
cd = new ConnectionDetector(getApplicationContext());
// Check for internet connection
if (!cd.isConnectingToInternet()) {
alert.showAlertDialog(AlbumsActivity.this, "Internet Connection Error",
"Please connect to working Internet connection", false);
return;
}
albumsList = new ArrayList<HashMap<String, String>>();
inputSearch = (EditText) findViewById(R.id.inputSearch);
inputSearch.addTextChangedListener(new TextWatcher() {
@Override
public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
AlbumsActivity.this.adapter.getFilter().filter(cs.toString());
}
@Override
public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
int arg3) {
}
@Override
public void afterTextChanged(Editable arg0) {
}
});
new LoadAlbums().execute();
ListView lv = getListView();
lv.setOnItemClickListener(new android.widget.AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View view, int arg2,
long arg3) {
// on selecting a single album
// TrackListActivity will be launched to show tracks inside the album
Intent i = new Intent(getApplicationContext(), TrackListActivity.class);
// send album id to tracklist activity to get list of songs under that album
String album_id = ((TextView) view.findViewById(R.id.album_id)).getText().toString();
i.putExtra("album_id", album_id);
startActivity(i);
}
});
LayoutInflater inflater = getLayoutInflater();
inflater.inflate(R.layout.list_item_albums, null);
imgClick = (ImageView)findViewById(R.id.row_click_imageView1);
imgClick.setOnClickListener(viewClickListener);
}
OnClickListener viewClickListener = new OnClickListener(){
@Override
public void onClick(View v){
showPopupMenu(v);
}
};
private void showPopupMenu(View v){
PopupMenu pop = new PopupMenu(AlbumsActivity.this, v);
pop.getMenuInflater().inflate(R.menu.menu,pop.getMenu());
pop.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
@Override
public boolean onMenuItemClick(MenuItem arg0) {
Toast.makeText(AlbumsActivity.this, arg0.toString(),Toast.LENGTH_LONG).show();
return true;
}
});
pop.show();
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data){
super.onActivityResult(requestCode, resultCode, data);
if(requestCode == 2){
if(resultCode == RESULT_OK){
String message = data.getStringExtra("Message");
TextView text = (TextView) findViewById(R.layout.activity_main);
text.setText(message);
}
}
}
class LoadAlbums extends AsyncTask<String, String, String> {
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(AlbumsActivity.this);
pDialog.setMessage("Loading ...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
protected String doInBackground(String... args) {
List<NameValuePair> params = new ArrayList<NameValuePair>();
String json = jsonParser.makeHttpRequest(URL_ALBUMS, "GET",
params);
Log.d("Albums JSON: ", "> " + json);
try {
albums = new JSONArray(json);
if (albums != null) {
for (int i = 0; i < albums.length(); i++) {
JSONObject c = albums.getJSONObject(i);
String id = c.getString(TAG_ID);
String name = c.getString(TAG_NAME);
String songs_count = c.getString(TAG_SONGS_COUNT);
HashMap<String, String> map = new HashMap<String, String>();
map.put(TAG_ID, id);
map.put(TAG_NAME, name);
map.put(TAG_SONGS_COUNT, songs_count);
albumsList.add(map);
}
}else{
Log.d("Albums: ", "null");
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
pDialog.dismiss();
runOnUiThread(new Runnable() {
public void run() {
AlbumsActivity.this.adapter = new SimpleAdapter(AlbumsActivity.this, albumsList, R.layout.list_item_albums, new String[] { TAG_ID, TAG_NAME, TAG_SONGS_COUNT }, new int[] {R.id.album_id, R.id.album_name, R.id.songs_count });
// updating listview
setListAdapter(AlbumsActivity.this.adapter);
}
});
}
}
}
logcat是：
09-24 04:05:48.381: E/Trace(3812): error opening trace file: No such file or directory (2)
09-24 04:05:49.761: D/dalvikvm(3812): GC_CONCURRENT freed 147K, 10% free 2659K/2936K, paused 21ms+7ms, total 157ms
09-24 04:05:49.901: D/AndroidRuntime(3812): Shutting down VM
09-24 04:05:49.901: W/dalvikvm(3812): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
09-24 04:05:49.921: E/AndroidRuntime(3812): FATAL EXCEPTION: main
09-24 04:05:49.921: E/AndroidRuntime(3812): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.projectsoftware/com.projectsoftware.AlbumsActivity}: java.lang.NullPointerException
09-24 04:05:49.921: E/AndroidRuntime(3812): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
09-24 04:05:49.921: E/AndroidRuntime(3812): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
09-24 04:05:49.921: E/AndroidRuntime(3812): at android.app.ActivityThread.access$600(ActivityThread.java:141)
09-24 04:05:49.921: E/AndroidRuntime(3812): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
09-24 04:05:49.921: E/AndroidRuntime(3812): at android.os.Handler.dispatchMessage(Handler.java:99)
09-24 04:05:49.921: E/AndroidRuntime(3812): at android.os.Looper.loop(Looper.java:137)
09-24 04:05:49.921: E/AndroidRuntime(3812): at android.app.ActivityThread.main(ActivityThread.java:5041)
09-24 04:05:49.921: E/AndroidRuntime(3812): at java.lang.reflect.Method.invokeNative(Native Method)
09-24 04:05:49.921: E/AndroidRuntime(3812): at java.lang.reflect.Method.invoke(Method.java:511)
09-24 04:05:49.921: E/AndroidRuntime(3812): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
09-24 04:05:49.921: E/AndroidRuntime(3812): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
09-24 04:05:49.921: E/AndroidRuntime(3812): at dalvik.system.NativeStart.main(Native Method)
09-24 04:05:49.921: E/AndroidRuntime(3812): Caused by: java.lang.NullPointerException
09-24 04:05:49.921: E/AndroidRuntime(3812): at com.projectsoftware.AlbumsActivity.onCreate(AlbumsActivity.java:147)
09-24 04:05:49.921: E/AndroidRuntime(3812): at android.app.Activity.performCreate(Activity.java:5104)
09-24 04:05:49.921: E/AndroidRuntime(3812): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
09-24 04:05:49.921: E/AndroidRuntime(3812): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
09-24 04:05:49.921: E/AndroidRuntime(3812): ... 11 more
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#d3d6db"
android:orientation="vertical" >
<LinearLayout
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:layout_marginLeft="@dimen/feed_item_margin"
android:layout_marginRight="@dimen/feed_item_margin"
android:layout_marginTop="@dimen/feed_item_margin"
android:background="@drawable/bg_parent_rounded_corner"
android:orientation="horizontal" >
<ImageView
android:id="@+id/flag"
android:layout_width="68dp"
android:layout_height="68dp"
android:layout_marginBottom="5dp"
android:layout_marginLeft="5dp"
android:layout_marginTop="5dp"/>
<TextView
android:id="@+id/album_id"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:layout_marginTop="20dp"
android:visibility="gone"
android:ems="8"
android:textSize="16sp"
android:textAppearance="?android:attr/textAppearanceLarge"
android:textColor="#333333" />
<TextView
android:id="@+id/album_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:layout_marginTop="20dp"
android:text="Some Item"
android:lines="1"
android:ems="8"
android:textSize="16sp"
android:textAppearance="?android:attr/textAppearanceLarge"
android:textColor="#333333" />
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:clickable="true" >
<ImageView
android:id="@+id/row_click_imageView1"
android:layout_width="30dp"
android:layout_height="35dp"
android:layout_gravity="right"
android:layout_alignParentRight="true"
android:clickable="true"
android:focusable="true"
android:src="@drawable/popup" />
<TextView
android:id="@+id/songs_count"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="10dp"
android:layout_marginTop="20dp"
android:visibility="gone"
android:lines="1"
android:ems="8"
android:textSize="16sp"
android:textAppearance="?android:attr/textAppearanceLarge"
android:textColor="#333333" />
</RelativeLayout>
</LinearLayout>
</LinearLayout>
答案 0 :(得分：2)
使用此代码处理点击列表器：
imgClick.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// your code
}
});
onCreate上设置的布局是activity_albums，但imgClick的ID位于布局list_item_albums上。
在OnCreate中展开的布局必须与您要处理Click
所以你可以使用这段代码：
LayoutInflater inflater = getLayoutInflater();
View view= inflater.inflate(R.layout.list_item_albums, null);
imgClick = (ImageView)view.findViewById(R.id.row_click_imageView1);
答案 1 :(得分：1)
试试这个：
imgClick.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v){
showPopupMenu(v);
}
});