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我在我的應用程序中有四個片段。第一個獲得GPS數據來計算速度，它工作正常。只要應用程序獲取GPS數據並移動到其他碎片，就會崩潰。僅供參考，其他片段都沒有任何代碼。當我從一個片段移動到另一個片段時，應用程序崩潰
這裏是我的MainActivity類別：
package ir.helpx.speedx;
import android.Manifest;
import android.content.pm.ActivityInfo;
import android.content.pm.PackageManager;
import android.os.Build;
import android.support.design.widget.TabLayout;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.view.WindowManager;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
Toolbar toolbar;
TabLayout tabLayout;
ViewPager viewPager;
ViewPagerAdapter viewPagerAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toolbar =(Toolbar)findViewById(R.id.toolBar);
setSupportActionBar(toolbar);
tabLayout = (TabLayout) findViewById(R.id.tabLayout);
viewPager = (ViewPager) findViewById(R.id.viewPager);
viewPagerAdapter = new ViewPagerAdapter(getSupportFragmentManager());
viewPagerAdapter.addFragments(new HomeFragment(), "Home");
viewPagerAdapter.addFragments(new CompassFragment(), "Compass");
viewPagerAdapter.addFragments(new HUDFragment(), "HUD");
viewPager.setAdapter(viewPagerAdapter);
tabLayout.setupWithViewPager(viewPager);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
setRequestedOrientation (ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
ActivityCompat.requestPermissions(this, new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION}, 1);
}
}
@Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
switch (requestCode) {
case 1:
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
Toast.makeText(this,"GPS permission granted", Toast.LENGTH_LONG).show();
// get Location from your device by some method or code
} else {
// show user that permission was denied. inactive the location based feature or force user to close the app
}
break;
}
}
}和我的MainActivity XML：
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="ir.helpx.speedx.MainActivity">
<android.support.design.widget.AppBarLayout
android:layout_height="wrap_content"
android:layout_width="368dp"
tools:layout_editor_absoluteY="0dp"
tools:layout_editor_absoluteX="8dp"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
<include
android:layout_height="wrap_content"
android:layout_width="match_parent"
layout="@layout/toolbar_layout"
/>
<android.support.design.widget.TabLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/tabLayout"
app:tabMode="fixed"
app:tabGravity="fill"
></android.support.design.widget.TabLayout>
<android.support.v4.view.ViewPager
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/viewPager"
></android.support.v4.view.ViewPager>
</android.support.design.widget.AppBarLayout>
</android.support.constraint.ConstraintLayout>，這裏是我的第一次片段稱爲主頁：
package ir.helpx.speedx;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;
/**
* A simple {@link Fragment} subclass.
*/
public class HomeFragment extends Fragment implements LocationListener{
public HomeFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
LocationManager mgr;
mgr = (LocationManager)getContext().getSystemService(getActivity().LOCATION_SERVICE);
mgr.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
this.onLocationChanged(null);
return inflater.inflate(R.layout.fragment_home, container, false);
}
//TextView msg1;
@Override
public void onLocationChanged(Location location) {
if (location==null){
TextView currentSpeed = null;
}
else {
float nCurrentSpeed = location.getSpeed();
TextView currentSpeed = (TextView) getView().findViewById(R.id.speed);
currentSpeed.setText((int)nCurrentSpeed*18/5+"");
//msg1=currentSpeed;
Toast.makeText(getActivity(), "Location Found!", Toast.LENGTH_LONG).show();
}
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onProviderDisabled(String provider) {
}
}<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="ir.helpx.speedx.HomeFragment">
<!-- TODO: Update blank fragment layout -->
<TextView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="@string/speed"
android:gravity="center"
android:textSize="180sp"
android:textStyle="bold"
android:textColor="@android:color/white"
android:id="@+id/speed"/>
</FrameLayout>，這裏是我的第二個片段：
package ir.helpx.speedx;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
/**
* A simple {@link Fragment} subclass.
*/
public class HUDFragment extends Fragment {
public HUDFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_hud, container, false);
}
}休息的片段類似於
我有一個工具欄XML：
最後我我ViewPagerAdapter：
package ir.helpx.speedx;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import java.util.ArrayList;
/**
* Created by abe on 5/29/2017.
*/
public class ViewPagerAdapter extends FragmentPagerAdapter {
ArrayList<Fragment> fragments = new ArrayList<>();
ArrayList<String> tabTitles = new ArrayList<>();
public void addFragments(Fragment fragments, String titles){
this.fragments.add(fragments);
this.tabTitles.add(titles);
}
public ViewPagerAdapter(FragmentManager fm){
super(fm);
}
@Override
public Fragment getItem(int position) {
return fragments.get(position);
}
@Override
public int getCount() {
return fragments.size();
}
@Override
public CharSequence getPageTitle(int position) {
return tabTitles.get(position);
}
}請幫助我！謝謝
請提供一個'崩潰'的解釋，它是什麼，更多的細節。 –
只要我轉到第三個或第四個片段，應用程序就會關閉。這發生在GPS定位時。否則（當GPS不在位）它工作得很好。 – abe
我想我可以通過添加----- viewPager.setOffscreenPageLimit（4）來修復它; ----我的MainActivity。我認爲這是因爲默認情況下，ViewPager在空閒狀態下僅保留視圖層次結構中的一個頁面。請告訴我做了正確的事！ – abe