This app is simple and all I want it to do is just keep the text in the text field even after I close the app. I looked through some tutorials but I can't seem to figure out how to get it to save with onSaveInstanceState and onRestoreInstanceState. How can I do it?
Here is notes.java:
public class notes extends Activity{
/** Called when the activity is first created. */
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.notes);
Button wg = (Button) findViewById(R.id.button3);
wg.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent intent = new Intent();
setResult(RESULT_OK, intent);
finish();
}
});
}
}
How do I save text input into preferences with onSaveInstanceState?
You don't. onSaveInstanceState() is only for updating the supplied Bundle, with data that the user might like to keep if it works out (e.g., onSaveInstanceState() is called as part of flipping from portrait to landscape or back again).
all I want it to do is just keep the text in the text field even after I close the app
Then onSaveInstanceState() is not the right place. Either save it in onPause(), or perhaps on an explicit action by the user (e.g., clicking a Save button or menu option).
Related
I have a problem. I have 3 activities (MainActivity, DetailsActivity, SettingsActivity) and in SettingsActivity I have a Togglebutton "Nightmode". What I want is, when the button is changed, change background of all three activities on gray color.
public class SettingsActivity extends AppCompatActivity {
//This is SettingsActivity(not Main one)
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_settings);
TextView SettingsTitle = (TextView) findViewById(R.id.SettingsTitle);
TextView NightText = (TextView) findViewById(R.id.NightmodeText);
ToggleButton toggleNightMode = (ToggleButton) findViewById(R.id.toggleNightmode);
final RelativeLayout NightBG = (RelativeLayout) findViewById(R.id.NightBG);
final LinearLayout DetailsBG = (LinearLayout) findViewById(R.id.mainBG);
final LinearLayout HomeBG = (LinearLayout) findViewById(R.id.HomeBG);
toggleNightMode.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
NightBG.setBackgroundColor(Color.parseColor("#545657"));
HomeBG.setBackgroundColor(Color.parseColor("#545657"));
DetailsBG.setBackgroundColor(Color.parseColor("#545657"));
}
});
NightBG is in the same activity as that java file (SettingsActivity). But HomeBG is in MainActivity and DetailsBG is in the DetailsActivity. Everytime I start the app, and press on that button, app craches. If I delete HomeBG and DetailsBG from this file, it works just fine with changing current layout's color to gray. Please help me.
One easy way to store little settings like this across multiple activities that may not be open/active at the time of the button click would be to use SharedPreferences.
It might be a little overkill for such a simple piece of code but you can always give it a try if you don't find anything else.
Your code could look something like this:
toggleNightMode.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// Set the color of this activity
int color = Color.parseColor("#545657")
View view = SettingsActivity.this.getWindow().getDecorView();
view.setBackgroundColor(color);
// Save color preference
SharedPreferences sharedPref = SettingsActivity.this.getSharedPreferences("bgColorFile",Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putInt("color", color);
editor.apply();
}
});
And then when you open your activities you place something like this in the onStart() or onCreate() method of your activity:
// Get the color preference
SharedPreferences sharedPref = getSharedPreferences("bgColorFile",Context.MODE_PRIVATE);
int colorValue = sharedPref.getInt("color", 0);
View view = this.getWindow().getDecorView();
view.setBackgroundColor(colorValue);
So what you're actually doing is storing the background color as persistent data and fetching it once you reopen/open the activity that you want to have the color on. The benefit of this method is that whenever you close your app the preferred background color will be remembered. I hope this helps.
Change background for current activity in the same activity. Since DetailsActivity is not running, you can't do that, it gives you null pointer. Is kind of you are trying to eat 3 apples and you have just one. After current activity is started, change background.
Update:
You can do that in current activity and just in current activity:
findViewById(android.R.id.content).setBackground(getColor(R.color.your_color));
Don't try to call this in other activities that are not running.
setBackground()
or
setBackgroundColor()
If your other activities are open, you should send a message to the other activities by using an Intent.
How to send string from one activity to another?
When you receive the Intent you could then set the background of the activity.
If your other activities are not open yet, you will not be able to send an Intent to them. In this case you could have each Activity reference a static value in your main activity that could contain the current background color. You would want to reference that value on the other activities on create functions.
Here is an example on how to reference a variable from another activity.
How do I get a variable in another activity?
This might not be the most pretty way to handle it but it should work.
as Ay Rue said you have 2 options: use static variable for that button, and then in onResume of each activity, check the value of the static variable (true or false). or you can save a private variable nightMode and then pass this value in the intent when you need to move to the other two activities.
don't set the background color if you already set before and have an updated background color.
I have simple counter application where, whenever you click the button, a textview shows the number increasing. If you click the button 10 times, the textview shows 10. Then, when I exit from the app and launch the app again, the application restarts all the activities I have done previously.
How can I continue to count where I left off previously? For example, I want to open my app and count up to 8 with the counter. When I exit, and after re-launching the activity, I want to continue counting where I left off from 8.
Please take a look at the source code:
TextView tv4;
ImageButton button5;
int counter=0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.content_ikinci);
tv4=(TextView)findViewById(R.id.textView4);
button5.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
counter++;
tv4.setText("" + counter);
}
});
On your activity's onStop() method try to save your data in SharedPreferences
SharedPreferences.Editor editor = getSharedPreferences(MY_PREFS_NAME, MODE_PRIVATE).edit();
editor.putInt("key", count);
editor.commit();
And when you launch it, on your main Activity onCreate() method retrieve your SharedPreferences value by key and continue where you left off
SharedPreferences prefs = getSharedPreferences(MY_PREFS_NAME, MODE_PRIVATE);
int count = prefs.getInt("key",0); //0 is the default value.
If you need to store little pieces of data throughout your activity's lifecycle it should be enough to store your counter variable in a Bundle inside onSaveInstanceState (Bundle outState) method. Note - don't forget to call super of that method after putting your variable into the Bundle.
This particular Bundle is passed to two methods on recreating Activity: onRestoreInstanceState() and onCreate() methods. So you can reset you instance variable from there.
For more info look here: http://developer.android.com/training/basics/activity-lifecycle/recreating.html
In settings activity, I have multiple fields, once the user press save all these fields will be stored separately as key-value in sharedPreference.
The problem is every editor change e.g.
editor.putString(SERVER, server.toString());
will fire onSharedPreferenceChangeListener
While I only need to fire it after update all values..
Is there any way to achieve this requirement?
Many thanks
There's only a way to do that. You can put editor.putString(SERVER, server.toString()); in runtime code, such as you pressing a button. Once the activity gets destroyed call editor.commit(); within onDestroy() method, it will saves the value and fires onSharedPreferenceChangeListener. Simply, waiting for the user to close the activity first which means that users already changed all of their settings.
Note: please make sure that editor is an instance variable or make a field for it.
EDIT
Here's an example for you:
public class SettingsActivity extends Activity {
// a field for preference
private SharedPreferences.Editor editor;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
SharedPreferences sharedpreferences = getSharedPreferences("MyPreference", Context.MODE_PRIVATE);
editor = sharedpreferences.edit();
// for example, edit the value using a button at runtime
Button button = (Button)findViewById(R.id.button1);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
editor.putString(SERVER, server.toString());
}
});
...
}
#Override
protected void onDestroy(){
// call commit to save all changes
editor.commit();
super.onDestroy();
}
}
I am a newbie to android development, trying to get buttons working. every time i use this code below, the error message "unfortunately the app has stopped". but when i remove the code the app runs but obviously the buttons do nothing. here is the code ive tried
public class MyActivity extends Activity {
/**
* Called when the activity is first created.
*/
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button button1 = (Button) findViewById(R.id.ExerciseButton);
button1.setOnClickListener (new View.OnClickListener(){
public void onClick(View v) {
setContentView(R.layout.exercises);
}
});
}
}
anybody able to help me out there? thanks
Don't try to load another View in the current activity. Navigate to a new ExercisesActivity.
Use:
public void onClick(View v) {
Intent intent = new Intent(ExercisesActivity.this, WcActivity.class);
startActivity(intent);
}
You can't call setContentView anymore after the view has loaded (which it obviously has to receive button clicks). Use a different approach, like showing and hiding views or using a ViewFlipper (see Calling setContentView() multiple times), using fragments (see Fragments) or starting a new activity.
Well, from your code, I see a couple of things:
I am usually familiar to using the onClickListener of the Button class if I want to use it for a button. Makes sense, doesn't it?
buttonOne.setOnClickListener(new Button.OnClickListener() {
public void onClick(View v) {
//Do stuff here
}
Second thing:
Start a new Activity (if that is what you want) by using an Intent:
Intent myIntent = new Intent(this, exercises.class);
startActivity(myIntent);
You CAN absolutaly call setContentView on any event, even after the view has loaded
I tried your code in a demo project and it is working fine. So, i think the error will be some where in your layout.(Let me know more if you need more help on this)
In my android app the user can enter the text in the EditView and the click on a button which takes him to an other activity where he can select a contact ... and then press a button which
brings him back to the first activity...
now the problem is I need to pass the selected contact to the first activity and display it (which i have done it using a bundle) but i am unable to retain already entered text in the EditView... which i should do (but the text should be retained with out passing it through the the bundle and getting it back)
thanks :)
The text in a view component is automagically saved by the OS, even after a soft kill (user changed phone orientation), but not after a hard kill, the user hit the back button while the parent activity was in focus. So, unless you are doing something non-standard, such as calling onSaveInstanceState without calling super.onSaveInstanceState, the data in the view state should persist.
One solution would be to save the text in the view component as a non view instance property before you launch the child activity, and just read this value back when the focus returns to the parent activity in the method onActivityResult.
JAL
EDIT: The Android Docs Activity page has been extensively updated. View state will not be saved if the widget does not have an ID.
EDIT: What I am saying is that the view state should be persisted by the OS. You should not need to save the view state manually. On a hard kill, you would need to save the state of your activity IF that is the expected behavior of the activity. So here is some code that saves the activity state. Given an instance variable:
String password;
Here we save state on a soft kill:
protected void onSaveInstanceState(Bundle outState){
password= editTextPassword.getText().toString();
outState.putString("password", password);
super.onSaveInstanceState(outState); // save view state
}
Here we save state on a hard kill
#Override
protected void onStop(){
super.onStop();
SharedPreferences prefs = getPreferences(MODE_PRIVATE);
SharedPreferences.Editor editor = prefs.edit();
editor.putString("password",password);
editor.commit();
Here we restore state in onCreate(Bundle savedInstanceState):
if( savedInstanceState!= null){ // get saved state from soft kill after first pass
try {
password= savedInstanceState.getString("password");
Log.d(TAG,"RestoredState!");
}
catch(Exception e){
Log.d(TAG,"FailedToRestoreState",e);
}
}
else { // get saved state from preferences on first pass
SharedPreferences prefs = getPreferences(MODE_PRIVATE); // singleton
if (prefs != null){
this.password= prefs.getString("password","");
Log.d(TAG,"gettingPrefs");
}
}
Log.d(TAG,"onCreate");
Also given the fact that IF onSaveInstanceState is called it will be called before onStop, it is possible to use the flags isSavedInstanceState and isSavedPreferences to write to prefs ONLY on a hard kill if you reset the flags in onResume as:
protected void onResume() {
super.onResume();
Log.d(TAG,"onResume");
isSavedInstanceState= false;
isSavedPrefs= false;
}
Setting the flags in onCreate will not result in the desired outcome.