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Question

I have two activities A and B.

B : is a setting activity that save all the setting in a shared preference.

A : is the main activity and I retrieve the shared preference that was saved in B activity

the problem is if the user use the application for the first time and launch the A activity its forced close.

I think because there is no shared preference saved yet...

the A activity:

public class DawaaActivity extends ListActivity implements View.OnClickListener {

Button add;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
SharedPreferences emportPref = getSharedPreferences("dawaaData",MODE_PRIVATE);
if (emportPref.getInt("exists", 0) == 1){
String dawaaList[] = {emportPref.getString("subject", null)};
setListAdapter(new ArrayAdapter<String>(DawaaActivity.this,
android.R.layout.simple_list_item_1,dawaaList));
}
initialaiz();
}

private void initialaiz() {

add = (Button) findViewById(R.id.button3);
add.setOnClickListener(this);
}

public void onClick(View v) {

Intent data = new Intent(DawaaActivity.this,SettingActivity.class);
startActivity(data);
}
}

the B activity:

public class SettingActivity extends Activity implements View.OnClickListener {
EditText et;
EditText et1;
Spinner list;
TimePicker startTime;
Button save;
Button cancel;
private SharedPreferences exportPref;

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);
setContentView(R.layout.setting);
initialaiz();
}
private void initialaiz() {

et = (EditText) findViewById(R.id.text);
et1 = (EditText) findViewById(R.id.text1);
list = (Spinner) findViewById(R.id.spinner);
startTime = (TimePicker) findViewById(R.id.timePicker);
save = (Button) findViewById(R.id.save);
cancel = (Button) findViewById(R.id.cancel);
save.setOnClickListener(this);
cancel.setOnClickListener(this);
}
public void onClick(View v) {

switch(v.getId()){
case R.id.save:
save();
Intent transferData = new Intent(SettingActivity.this,DawaaActivity.class);
startActivity(transferData);
break;
case R.id.cancel:
finish();
break;
}
}
private void save() {

exportPref = getSharedPreferences("dawaaData",MODE_PRIVATE);
SharedPreferences.Editor editor = exportPref.edit();
editor.putString("subject", et.getText().toString());
editor.putString("dosesC", et1.getText().toString());
editor.putString("doses", list.getSelectedItem().toString());
editor.putInt("hour", startTime.getCurrentHour());
editor.putInt("minute", startTime.getCurrentMinute());
editor.putInt("exists", 1);
editor.commit();
Toast.makeText(SettingActivity.this,"data has been saved" ,Toast.LENGTH_SHORT).show();
}

}

how I can solve the problem ???

EDIT:

I add the ListView in my layout

and I edit the class like this:

public class DawaaActivity extends Activity implements View.OnClickListener {

ListView myList;
SharedPreferences emportPref = getSharedPreferences("dawaaData",MODE_PRIVATE);
String dawaaList[] = {emportPref.getString("subject", "no data yet")};
myList = (ListView) findViewById(R.id.ListView);
myList.setAdapter(new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, dawaaList));

and this is the logcat:

08-28 14:56:41.112: E/AndroidRuntime(273):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2585)
08-28 14:56:41.112: E/AndroidRuntime(273):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
08-28 14:56:41.112: E/AndroidRuntime(273):  at android.app.ActivityThread.access$2300(ActivityThread.java:125)
08-28 14:56:41.112: E/AndroidRuntime(273):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
08-28 14:56:41.112: E/AndroidRuntime(273):  at android.os.Handler.dispatchMessage(Handler.java:99)
08-28 14:56:41.112: E/AndroidRuntime(273):  at android.os.Looper.loop(Looper.java:123)
08-28 14:56:41.112: E/AndroidRuntime(273):  at android.app.ActivityThread.main(ActivityThread.java:4627)
08-28 14:56:41.112: E/AndroidRuntime(273):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
08-28 14:56:41.112: E/AndroidRuntime(273):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
08-28 14:56:41.112: E/AndroidRuntime(273):  at android.content.ContextWrapper.getSharedPreferences(ContextWrapper.java:146)
08-28 14:56:41.112: E/AndroidRuntime(273):  at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
08-28 14:56:41.112: E/AndroidRuntime(273):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2577)
08-28 14:59:54.272: E/AndroidRuntime(303):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2585)
08-28 14:59:54.272: E/AndroidRuntime(303):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
08-28 14:59:54.272: E/AndroidRuntime(303):  at android.app.ActivityThread.access$2300(ActivityThread.java:125)
08-28 14:59:54.272: E/AndroidRuntime(303):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
08-28 14:59:54.272: E/AndroidRuntime(303):  at android.os.Handler.dispatchMessage(Handler.java:99)
08-28 14:59:54.272: E/AndroidRuntime(303):  at android.os.Looper.loop(Looper.java:123)
08-28 14:59:54.272: E/AndroidRuntime(303):  at android.app.ActivityThread.main(ActivityThread.java:4627)
08-28 14:59:54.272: E/AndroidRuntime(303):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
08-28 14:59:54.272: E/AndroidRuntime(303):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
08-28 14:59:54.272: E/AndroidRuntime(303):  at android.content.ContextWrapper.getSharedPreferences(ContextWrapper.java:146)
08-28 14:59:54.272: E/AndroidRuntime(303):  at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
08-28 14:59:54.272: E/AndroidRuntime(303):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2577)
08-28 15:02:26.632: E/AndroidRuntime(331):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2585)

08-28 15:02:26.632: E/AndroidRuntime(331): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679) 08-28 15:02:26.632: E/AndroidRuntime(331): at android.app.ActivityThread.access$2300(ActivityThread.java:125) 08-28 15:02:26.632: E/AndroidRuntime(331): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033) 08-28 15:02:26.632: E/AndroidRuntime(331): at android.os.Handler.dispatchMessage(Handler.java:99) 08-28 15:02:26.632: E/AndroidRuntime(331): at android.os.Looper.loop(Looper.java:123) 08-28 15:02:26.632: E/AndroidRuntime(331): at android.app.ActivityThread.main(ActivityThread.java:4627) 08-28 15:02:26.632: E/AndroidRuntime(331): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 08-28 15:02:26.632: E/AndroidRuntime(331): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626) 08-28 15:02:26.632: E/AndroidRuntime(331): at android.content.ContextWrapper.getSharedPreferences(ContextWrapper.java:146) 08-28 15:02 :26.632: E/AndroidRuntime(331): at android.app.Instrumentation.newActivity(Instrumentation.java:1021) 08-28 15:02:26.632: E/AndroidRuntime(331): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2577)

Answer 1

The problem is probably here:

String dawaaList[] = {emportPref.getString("subject", null)};
setListAdapter(new ArrayAdapter<String>(DawaaActivity.this,
android.R.layout.simple_list_item_1, dawaaList));

If you don't have any subject you will get a null and then probably a nullpointer somewhere.

Try to check the null, or initialize it with something if null, like:

if (dawaaList[] == null) { 
   new String[]{"No subjects"}; 
}

and please, post your logcat for further help.

EDIT:

You can handle it this way:

just add a ListView in your layout

    <ListView
        android:id="@+id/myListView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        />

and populate it in your Activity

    setContentView(R.layout.main);
    ListView listView = (ListView) findViewById(R.id.myListView);
    SharedPreferences pref = getSharedPreferences("dawaaData", MODE_PRIVATE);
    String items = pref.getString("subject", "item1,item2,item3");
    String[] listItems = items.split(",");
    listView.setAdapter(new ArrayAdapter<String>(this,  android.R.layout.simple_list_item_1, listItems));

I've choose a comma as a delimiter because SharedPreferences cannot store arrays. You should use a Set and pref.getStringSet (from api 11), or serialize the list (json o anything).

Answer 2

The App A gets closed because the first time you dont have initialized the values. The simplest way is to wrap the code that read the value from the SharedPreferences in a try catch(Throwable t)

Answer 3

This two functions will solve your problem, First one is to save preference that you will need to cal in class A, where you want to store value

public void saveSharedPreference() {
        SharedPreferences myPrefs = this.getSharedPreferences("myPrefs",
                MODE_WORLD_READABLE);
        SharedPreferences.Editor prefsEditor = myPrefs.edit();
        prefsEditor.putString(stringname, stringvalue);
        prefsEditor.commit();
    }

And on your B activity, you have to call LoadPreferences function

private void LoadPreferences() {
        SharedPreferences sharedPreferences = this.getSharedPreferences(
                "myPrefs", MODE_WORLD_READABLE);
        String yourvariable= sharedPreferences.getString(name, "0"); // it will take 0 as default value if variable is empty and you can set you own default value  }