我正在尝试使用sharedpreferences来保存您在微调器中选择的int的活动，并且我试图在用户单击菜单时使用sharedpreferences int的不同值重新加载活动（之前在微调器中选择了，但是当用户重新加载应用程序时，它会崩溃并显示以下消息：
08-19 19:02:56.145: D/AndroidRuntime(23142): Shutting down VM
08-19 19:02:56.145: W/dalvikvm(23142): threadid=1: thread exiting with uncaught exception (group=0x4164bd40)
08-19 19:02:56.146: E/AndroidRuntime(23142): FATAL EXCEPTION: main
08-19 19:02:56.146: E/AndroidRuntime(23142): Process: com.example.fluviales, PID: 23142
08-19 19:02:56.146: E/AndroidRuntime(23142): java.lang.NullPointerException
08-19 19:02:56.146: E/AndroidRuntime(23142): at com.example.fluviales.Home_fragment$1$1.run(Home_fragment.java:49)
08-19 19:02:56.146: E/AndroidRuntime(23142): at android.os.Handler.handleCallback(Handler.java:733)
08-19 19:02:56.146: E/AndroidRuntime(23142): at android.os.Handler.dispatchMessage(Handler.java:95)
08-19 19:02:56.146: E/AndroidRuntime(23142): at android.os.Looper.loop(Looper.java:136)
08-19 19:02:56.146: E/AndroidRuntime(23142): at android.app.ActivityThread.main(ActivityThread.java:5086)
08-19 19:02:56.146: E/AndroidRuntime(23142): at java.lang.reflect.Method.invokeNative(Native Method)
08-19 19:02:56.146: E/AndroidRuntime(23142): at java.lang.reflect.Method.invoke(Method.java:515)
08-19 19:02:56.146: E/AndroidRuntime(23142): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
08-19 19:02:56.146: E/AndroidRuntime(23142): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
08-19 19:02:56.146: E/AndroidRuntime(23142): at dalvik.system.NativeStart.main(Native Method)
对我来说奇怪的是，如果我使用
重新加载活动Intent intent = getIntent();
finish();
startActivity(intent);
活动崩溃，但是如果我在多任务中关闭应用程序并重新打开它，则代码可以正常工作！
这是我的MainActivity
public class MainActivity extends ActionBarActivity implements OnPageChangeListener{
private static final String PREFS_NAME = "ciudad";
private static final String DATA_TAG = "ciudad";
private static final int NUM_PAGES = 2;
public ViewPager mPager;
public PagerAdapter mPagerAdapter;
String[] ciudades = { "Desde Paraná", "Desde Santa Fe", "Desde el pozo", "Desde abogacia"};
public int ciudad;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mPager = (ViewPager) findViewById(R.id.pager);
mPagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager());
final SharedPreferences sharedPref = MainActivity.this.getPreferences(Context.MODE_PRIVATE);
int ciudad_sp = sharedPref.getInt("ciudad", 0);
final TextView tvv = (TextView) findViewById(R.id.debug);
tvv.setText(String.valueOf(ciudad_sp));
Spinner sp = (Spinner) findViewById(R.id.spinner1);
ArrayAdapter adapter = ArrayAdapter.createFromResource( this, R.array.opciones, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
sp.setAdapter(adapter);
sp.setSelection(ciudad_sp);
sp.setOnItemSelectedListener(new OnItemSelectedListener() {
public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) {
ciudad = position;
Toast.makeText(parentView.getContext(), ciudades[position], Toast.LENGTH_SHORT).show();
SharedPreferences.Editor editor = sharedPref.edit();
editor.putInt("ciudad", position);
editor.commit();
}
public void onNothingSelected(AdapterView<?> parentView) {
mPager.getAdapter().notifyDataSetChanged();
}
});
// Instantiate a ViewPager and a PagerAdapter.
mPager.setOnPageChangeListener(this);
mPager.setAdapter(mPagerAdapter);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case 0:
Intent intent = getIntent();
finish();
startActivity(intent);
return true;
default:
return super.onOptionsItemSelected(item);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu){
super.onCreateOptionsMenu(menu);
createMenu(menu);
return true;
}
private void createMenu(Menu menu){
MenuItem mnu1 = menu.add(0, 0, 0, "Reload");
{
mnu1.setAlphabeticShortcut('a');
mnu1.setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM);
}
}
@Override
public void onBackPressed() {
if (mPager.getCurrentItem() == 0) {
// If the user is currently looking at the first step, allow the system to handle the
// Back button. This calls finish() on this activity and pops the back stack.
super.onBackPressed();
} else {
// Otherwise, select the previous step.
mPager.setCurrentItem(mPager.getCurrentItem() - 1);
}
}
/**
* A simple pager adapter that represents 5 ScreenSlidePageFragment objects, in
* sequence.
*/
private class ScreenSlidePagerAdapter extends FragmentPagerAdapter {
public ScreenSlidePagerAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
SharedPreferences sharedPref = MainActivity.this.getPreferences(Context.MODE_PRIVATE);
int ciudad_sp = sharedPref.getInt("ciudad", 0);
if(ciudad_sp == 0){
switch(position){
case 0:
return new Home_fragment();
case 1:
return new Next_fragment();
}
}else if(ciudad_sp == 1){
switch(position){
case 0:
return new Home_fragment_staFe();
case 1:
return new Next_fragment_staFe();
}
}
return null;
}
@Override
public int getCount() {
return NUM_PAGES;
}
}
@Override
public void onPageScrollStateChanged(int arg0) {
// TODO Auto-generated method stub
}
@Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
// TODO Auto-generated method stub
}
@Override
public void onPageSelected(int position) {
String [] hola = {"Siguiente cole", "Siguiente siguiente cole" };
setTitle(hola[position]);
}
}
这是我的Home_fragment片段
public class Home_fragment extends Fragment{
public int numeroDelArray, cuantosQuedan, HoraActual_en_minutos;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
ViewGroup rootView = (ViewGroup) inflater.inflate(R.layout.inicio, container, false);
final int[] horas = { 1,3,4,5,6,6,7,7,7,8,8,9,9,9,10,11,11,11,12,13,13,14,14,14,15,15,16,16,17,17,18,18,19,19,20,20,21,21,22,23 };
final int[] minutos = { 0,0,0,10,10,20,0,10,30,20,40,20,30,50,40,0,40,50,10,10,20,0,10,30,20,40,30,50,0,40,0,50,10,20,0,20,10,30,40,50 };
final Handler mHandler = new Handler();
new Thread(new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
while (true) {
try {
Thread.sleep(1000);
mHandler.post(new Runnable() {
@Override
public void run() {
// TODO Auto-generated method stub
// Write your code here to update the UI.
numeroDelArray = checkHour();
// Down here is the error that the logcat shows
TextView tv_minutos = (TextView) getView().findViewById(R.id.minutos);
TextView tv_horaDelQueSale = (TextView) getView().findViewById(R.id.textoQueQueda);
Calendar c = Calendar.getInstance();
HoraActual_en_minutos = (c.get(Calendar.HOUR_OF_DAY) * 60 ) + c.get(Calendar.MINUTE);
cuantosQuedan = horas[numeroDelArray]*60 + minutos[numeroDelArray] - HoraActual_en_minutos;
if(cuantosQuedan > 60){
tv_minutos.setText("+60");
}else{
tv_minutos.setText(String.valueOf(cuantosQuedan));
}
tv_horaDelQueSale.setText("QUE SALE A LAS " + String.valueOf(String.format("%02d", horas[numeroDelArray])) + ":" + String.valueOf(String.format("%02d", minutos[numeroDelArray])));
}
});
} catch (Exception e) {
// TODO: handle exception
}
}
}
}).start();
return rootView;
}
private int checkHour() {
// TODO Auto-generated method stub
int[] horas = { 1,3,4,5,6,6,7,7,7,8,8,9,9,9,10,11,11,11,12,13,13,14,14,14,15,15,16,16,17,17,18,18,19,19,20,20,21,21,22,23 };
int[] minutos = { 0,0,0,10,10,20,0,10,30,20,40,20,30,50,40,0,40,50,10,10,20,0,10,30,20,40,30,50,0,40,0,50,10,20,0,20,10,30,40,50 };
int minutosQueUso = 9999, lugarQueQueda = 0;
Calendar c = Calendar.getInstance();
int HoraActualenminutos = (c.get(Calendar.HOUR_OF_DAY) * 60 ) + c.get(Calendar.MINUTE);
if (horas.length != minutos.length){
Toast.makeText(getActivity(), "No acomodaste bien la hora de los minutos", Toast.LENGTH_SHORT).show();
}else{
for(int lugar = 0; lugar < minutos.length; lugar++){
if((horas[lugar]*60 + minutos[lugar] - HoraActualenminutos) > 0 && (horas[lugar]*60 + minutos[lugar] - HoraActualenminutos) < minutosQueUso ){
minutosQueUso = horas[lugar]*60 + minutos[lugar] - HoraActualenminutos;
lugarQueQueda = lugar;
}
}
}
return lugarQueQueda;
}}
我的另一个问题是，如果有人知道在用户更改微调器值时重新加载活动的方法，我尝试在我的setOnItemSelected中重新加载活动，但它会生成一个无限循环，谢谢先进！