方法 getApplicationContext() 未定义 - 片段问题 [英] The method getApplicationContext() is undefined - fragment issues
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问题描述
我收到以下错误:方法 getApplicationContext() 未定义方法 findViewById(int) 未定义为 Fragment1 类型
I am getting the following errors: The method getApplicationContext() is undefined The method findViewById(int) is undefined for the type Fragment1
当我的类扩展到 Activity 而不是 Fragment 时，这些错误似乎消除了，但重要的是该 Activity 仍然是一个 Fragment，所以我不太确定如何解决这个问题.
These errors seem to be eliminated when my class is extended to an Activity as oppose to a fragment, but it is important that this activity remains as a fragment, so I am not too sure how to work this out.
任何帮助将不胜感激.提前致谢.
Any help would be greatly appreciated. Thanks in advance.
下面是代码
public class Fragment1 extends Fragment {
private String currentUserId;
private ArrayAdapter<String> namesArrayAdapter;
private ArrayList<String> names;
private ListView usersListView;
private Button logoutButton;
String userGender = ParseUser.getCurrentUser().getString("Gender");
String activityName = ParseUser.getCurrentUser().getString("ActivityName");
Number maxDistance = ParseUser.getCurrentUser().getNumber("Maximum_Distance");
String userLookingGender = ParseUser.getCurrentUser().getString("Looking_Gender");
Number minimumAge = ParseUser.getCurrentUser().getNumber("Minimum_Age");
Number maximumAge = ParseUser.getCurrentUser().getNumber("Maximum_Age");
Number userage = ParseUser.getCurrentUser().getNumber("Age");
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
if (container == null){
return null;
}
return (LinearLayout)inflater.inflate(R.layout.fragment1_layout,
container,false);
logoutButton = (Button) findViewById(R.id.logoutButton);
logoutButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
ParseUser.logOut();
Intent intent = new Intent(getApplicationContext(), LoginActivity.class);
startActivity(intent);
}
});
setConversationsList();
}
private void setConversationsList() {
currentUserId = ParseUser.getCurrentUser().getObjectId();
names = new ArrayList<String>();
// String userActivitySelectionName = null;
ParseQuery<ParseUser> query = ParseUser.getQuery();
// query.whereEqualTo("ActivityName",userActivitySelectionName);
query.whereNotEqualTo("objectId", ParseUser.getCurrentUser().getObjectId());
// users with Gender = currentUser.Looking_Gender
query.whereEqualTo("Gender", userLookingGender);
// users with Looking_Gender = currentUser.Gender
query.whereEqualTo("Looking_Gender", userGender);
query.setLimit(1);
query.whereEqualTo("ActivityName", activityName);
query.whereGreaterThanOrEqualTo("Minimum_Age", minimumAge).whereGreaterThanOrEqualTo("Age", userage);
query.whereLessThanOrEqualTo("Maximum_Age", maximumAge).whereLessThanOrEqualTo("Age", userage);
// query.whereWithinKilometers("Maximum_Distance", point, maxDistance)
query.findInBackground(new FindCallback<ParseUser>() {
public void done(List<ParseUser> userList, ParseException e) {
if (e == null) {
for (int i=0; i<userList.size(); i++) {
names.add(userList.get(i).get("Name").toString());
names.add(userList.get(i).get("Headline").toString());
names.add(userList.get(i).get("Age").toString());
// names.add(userList.get(i).getParseObject("ProfilePicture").;
}
usersListView = (ListView)findViewById(R.id.usersListView);
namesArrayAdapter =
new ArrayAdapter<String>(getApplicationContext(),
R.layout.user_list_item, names);
usersListView.setAdapter(namesArrayAdapter);
usersListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> a, View v, int i, long l) {
openConversation(names, i);
}
});
} else {
Toast.makeText(getApplicationContext(),
"Error loading user list",
Toast.LENGTH_LONG).show();
}
}
});
}
public void openConversation(ArrayList<String> names, int pos) {
ParseQuery<ParseUser> query = ParseUser.getQuery();
query.whereEqualTo("Name", names.get(pos));
query.findInBackground(new FindCallback<ParseUser>() {
public void done(List<ParseUser> user, ParseException e) {
if (e == null) {
Intent intent = new Intent(getApplicationContext(), MessagingActivity.class);
intent.putExtra("RECIPIENT_ID", user.get(0).getObjectId());
startActivity(intent);
} else {
Toast.makeText(getApplicationContext(),
"Error finding that user",
Toast.LENGTH_SHORT).show();
}
}
});
}
}
更新无法访问 setConversationList 的代码错误
Update Unreachable code error for setConversationList
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
if (container == null){
return null;
}
return (LinearLayout)inflater.inflate(R.layout.fragment1_layout,
container,false);
setConversationsList();
}
private void setConversationsList() {
currentUserId = ParseUser.getCurrentUser().getObjectId();
names = new ArrayList<String>();
// String userActivitySelectionName = null;
ParseQuery<ParseUser> query = ParseUser.getQuery();
更新
启动活动后，我收到以下消息:
Upon launching the activity, I received the following message:
08-15 14:52:16.365: E/AndroidRuntime(3332): FATAL EXCEPTION: main
08-15 14:52:16.365: E/AndroidRuntime(3332): Process: com.dooba.beta, PID: 3332
08-15 14:52:16.365: E/AndroidRuntime(3332): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.dooba.beta/com.dooba.beta.usermatch}: java.lang.NullPointerException
08-15 14:52:16.365: E/AndroidRuntime(3332): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
08-15 14:52:16.365: E/AndroidRuntime(3332): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
08-15 14:52:16.365: E/AndroidRuntime(3332): at android.app.ActivityThread.access$800(ActivityThread.java:135)
08-15 14:52:16.365: E/AndroidRuntime(3332): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
08-15 14:52:16.365: E/AndroidRuntime(3332): at android.os.Handler.dispatchMessage(Handler.java:102)
08-15 14:52:16.365: E/AndroidRuntime(3332): at android.os.Looper.loop(Looper.java:136)
08-15 14:52:16.365: E/AndroidRuntime(3332): at android.app.ActivityThread.main(ActivityThread.java:5017)
08-15 14:52:16.365: E/AndroidRuntime(3332): at java.lang.reflect.Method.invokeNative(Native Method)
08-15 14:52:16.365: E/AndroidRuntime(3332): at java.lang.reflect.Method.invoke(Method.java:515)
08-15 14:52:16.365: E/AndroidRuntime(3332): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
08-15 14:52:16.365: E/AndroidRuntime(3332): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
08-15 14:52:16.365: E/AndroidRuntime(3332): at dalvik.system.NativeStart.main(Native Method)
08-15 14:52:16.365: E/AndroidRuntime(3332): Caused by: java.lang.NullPointerException
08-15 14:52:16.365: E/AndroidRuntime(3332): at com.dooba.beta.usermatch.initialisePaging(usermatch.java:32)
08-15 14:52:16.365: E/AndroidRuntime(3332): at com.dooba.beta.usermatch.onCreate(usermatch.java:20)
08-15 14:52:16.365: E/AndroidRuntime(3332): at android.app.Activity.performCreate(Activity.java:5231)
08-15 14:52:16.365: E/AndroidRuntime(3332): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
08-15 14:52:16.365: E/AndroidRuntime(3332): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
08-15 14:52:16.365: E/AndroidRuntime(3332): ... 11 more
下面是调用fragment的活动页面
Below is the activity page that calls for the fragment
import java.util.List;
import java.util.Vector;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import android.view.Menu;
import android.view.MenuItem;
public class usermatch extends FragmentActivity {
private PageAdapter mPagerAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.viewpager_layout);
initialisePaging();
}
private void initialisePaging() {
// TODO Auto-generated method stub
List<Fragment> fragments = new Vector<Fragment>();
fragments.add(Fragment.instantiate(this, Fragment1.class.getName()));
fragments.add(Fragment.instantiate(this, Fragment2.class.getName()));
fragments.add(Fragment.instantiate(this, Fragment3.class.getName()));
mPagerAdapter = new PageAdapter(this.getSupportFragmentManager(), fragments);
ViewPager pager = (ViewPager) findViewById(R.id.viewpager);
pager.setAdapter(mPagerAdapter);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.mood, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
更新 2下面是我在 logcat 中收到的消息
Update 2 Below is the message I receive in logcat
08-15 17:42:28.863: E/AndroidRuntime(4974): FATAL EXCEPTION: main
08-15 17:42:28.863: E/AndroidRuntime(4974): Process: com.dooba.beta, PID: 4974
08-15 17:42:28.863: E/AndroidRuntime(4974): java.lang.NullPointerException
08-15 17:42:28.863: E/AndroidRuntime(4974): at com.dooba.beta.Fragment1$1.done(Fragment1.java:108)
08-15 17:42:28.863: E/AndroidRuntime(4974): at com.parse.FindCallback.internalDone(FindCallback.java:45)
08-15 17:42:28.863: E/AndroidRuntime(4974): at com.parse.FindCallback.internalDone(FindCallback.java:1)
08-15 17:42:28.863: E/AndroidRuntime(4974): at com.parse.Parse$6$1.run(Parse.java:888)
08-15 17:42:28.863: E/AndroidRuntime(4974): at android.os.Handler.handleCallback(Handler.java:733)
08-15 17:42:28.863: E/AndroidRuntime(4974): at android.os.Handler.dispatchMessage(Handler.java:95)
08-15 17:42:28.863: E/AndroidRuntime(4974): at android.os.Looper.loop(Looper.java:136)
08-15 17:42:28.863: E/AndroidRuntime(4974): at android.app.ActivityThread.main(ActivityThread.java:5017)
08-15 17:42:28.863: E/AndroidRuntime(4974): at java.lang.reflect.Method.invokeNative(Native Method)
08-15 17:42:28.863: E/AndroidRuntime(4974): at java.lang.reflect.Method.invoke(Method.java:515)
08-15 17:42:28.863: E/AndroidRuntime(4974): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
08-15 17:42:28.863: E/AndroidRuntime(4974): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
08-15 17:42:28.863: E/AndroidRuntime(4974): at dalvik.system.NativeStart.main(Native Method)
推荐答案
您可以使用 getActivity() 获取包含片段的活动.
You can get the activity that contains the fragment with getActivity().
因此 getActivity().getApplicationContext() 会起作用.
getActivity().findViewById(int) 也可以.
不过，请确保不要在 onActivityCreated() 之前使用 getActivity()，因为它会在此之前返回 null.
Make sure, though, you don't use getActivity() prior to onActivityCreated(), since it would return null prior to that.
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