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Android Java Starting an activity if a condition is true

I would like to start an activity only if the string I pass with putExtra from another activity equals 'search' like so:
action = intent.getStringExtra("cause");
Button btnBack = findViewById(R.id.btnBack);
btnBack.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if(action == "search") {
Intent intent2 = new Intent(profiloutente.this, ricerca.class);
startActivity(intent2);
}
}
});
But, the condition always seems to be false (so the activity doesn't start) even if the variable containing the get Extra equals "search". I don't understand why this happens. Could someone help me?

The obvious probklem is that you are using == on a String. How do I compare strings in Java?
Another problem is that action is read outside of listener. That may be the intent, but I can't tell in isolation - if it is the surrounding the entire listener in the if statement would make more sense. action will take the value from getStringExtra at the time you run the surrounding code, not when the listener is fired.
There may be other issues.

if(action.equals("search"))
instead
if(action == "search")

Check checkbox from antoher activity

I was wondering if anyone could tell me how I could check a checkBox in an activity from another activity.
I'm making a homework app and I want to put a check next to the questions that have been completed.
So the first activity has a list of questions and next to them are unchecked boxes. When you click a question, the app takes you to the second activity. In the second activity, I want to check the box of the question that was completed.

You should use SharedPreferences for that. call this in the first activity:
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
prefs.putBoolean("KEY", <your value>).apply();
and something similar in another activity:
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
boolean isTicked = prefs.getBoolean("KEY", <default boolean value>);
where KEY can be anything, for example, your question's number

You should use intent and bundle logic for passing data between activities.(in most cases)
In the first activity, whenever you are creating the second activity, you pass your data.
Intent intent = new Intent(FirstActivity.this,SecondActivity.class);
intent.putExtra("checked",checkBox.isChecked());
startActivity(intent);
In the second activity you receive your data by using :
Intent receivedIntent = getIntent();
boolean finalChecked = receivedIntent.getExtras().getBoolean("checked");
//now you can apply your logic with finalChecked variable

You can save checked check question to a bundle and pass it as extra to your second activity through intent and read it from that intent inside your second activity
In your first activity do something like this
public class FirstActivity extends Activity {
public static final String EXTRA_CHECKED_QUESTION = "Checked Question";
// other codes here
private void startSecondActivity() {
String checkedQuestion = getCheckedQuestion(); // a method to get checked question
Intent intent = new Intent(this, SecondActivity.class);
intent.putExtra(FirstActivity.EXTRA_CHECKED_QUESTION, checkedQuestion);
startActivity(intent);
}
}
then in your second activity
public class SecondActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstance) {
// other codes
String checkedQuestion = getIntent().getStringExtra(FirstActivity.EXTRA_CHECKED_QUESTION);
// do whatever you want with checkQuestion
}
}
Please note that the string which you pass as first parameter to putExtra() method in FirstActivity, should be same as the string you are using with getStringExtra() to retrieve your extra in SecondActivity, otherwise you can not retrieve your passed extra in SecondActivity.
Also, I did not write these codes inside idea, so there might be syntax error
Read more about intent here

Quit showing an Activity when CheckBox is checked

I have got a DialogActivity with a "do not show anymore" CheckBox.
What I need it to do is exactly like the CheckBox says. When the CheckBox is checked the Activity doesn't have to be displayed to the user anymore, no matter if the app is restarted or killed.
public class PopUpInfoActivity extends Activity {
static final String PREFS = "preference_file";
#Override
public void onCreate(Bundle state) {
setContentView(R.layout.popupinfo_layout);
CheckBox chk = (CheckBox) findViewById(R.id.dontshow_checkbox);
chk.setChecked(PreferenceManager.getDefaultSharedPreferences(this).getBoolean("value", false));
chk.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
//store isChecked to Preferences
SharedPreferences settings = getSharedPreferences(PREFS, 0);
SharedPreferences.Editor editor = settings.edit();
editor.putBoolean("isChecked", false);
PreferenceManager.getDefaultSharedPreferences(PopUpInfoActivity.this).edit().putBoolean("value", isChecked).apply();
}
});
Intent intent = new Intent(PopUpInfoActivity.this, ChordsListActivity.class);
if (!chk.isChecked()) {
// run activity
super.onCreate(state);
} else {
startActivity(intent);
}
}
}
If I do it like this the App crashes.
If I replace the else with:
else {
onStop()
}
The code doesn't work as expected.
I would really appreciate if you could help me fix this problem!
EDIT:
This is what I have got in my ChordsListActivity, which is the activity that calls the PopUpInfoActivity but I do not get what I should put in my if() statement.
Intent legendaIntent = new Intent(ChordsListActivity.this, PopUpInfoActivity.class);
if(/*what's here?*/)
startActivity(legendaIntent);

In that MainActivity read your preference key (Show_Dialog), if it is true then launch PopUpInfoActivity otherwise launch ChordsListActivity.
The logic should be in the Mother Activity
In your PopUpInfoActivity you should only edit the preference key to false if the user checks out the ChekBox
To do so, please create a preferences.xml file under res/xml, inside this file you have to create a key (Boolean) that you will store inside the status of PopUpInfoActivity.Checkbox, the default will be (True).
here is an example
<CheckBoxPreference
android:key="Show_Dialog"
android:defaultValue="true" />
From your MainActivity you should read this value like this:
SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(this);
Boolean showDlg = sharedPref.getBoolean("Show_Dialog", true);
if the showDlg is true then you popup your dialog, otherwise continue what you want to do.
of course you need to change the value of Show_Dialog if the user checks the checkbox, you can do it like this:
SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(context);
SharedPreferences.Editor preferencesEditor = sharedPref.edit();
preferencesEditor.putBoolean("Show_Dialog", false);
preferencesEditor.commit();
in this way, you can be sure that your main activity will read the Show_Dialog as false next time the user launches your application
Good luck

Firstly, super.onCreate() must be the first call in any Activity's onCreate().
Secondly, store the value of the SharedPrefence in a boolean instead of directly setting the CheckBox, and use that before setContentView() to finish your current Activity and launch the next one if true. If not, carry on with the UI stuff and anything else you need.

How can I create multiple screen views in eclipse?

I'm using Eclipse for windows 7 and I am making an informative application(just text and offline content).
In my app I have about 180 buttons. Each button will lead to another screen. I need to know how to make each button lead to a specific screen?
And also, is there a way to like duplicate the code and not spend hours copying and pasting the code 180 times?
Check my code below for the first two screens:
That's for the MainActivity.java:
public void addListenerOnButton() {
final Context context = this;
button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
Intent intent = new Intent(context, MainActivity2.class);
startActivity(intent);
}
});
}
I mean that code is only for one single button. Am I supposed to repeat this for every single button?
and also a question, how many classes should I do? 180 main activities, 180 fragment_main.xml and 180 activity_main.xml?

That's my idea, since your application is just a "informative application" you can create two activities:
Main activity with buttons
"Information page"
To do it i need info about how you get this informations:
In a SQLite Database.
In a string-array
Personally, i prefer a SQLite DB it allows you to improve it without problems in the future.
About the Information activity:
Example: in your layout you have a TextView where will be added the text which this activity should be passed.
To make it dynamic in your case we pass the string to show using Intents, in our onCreate we add something like this:
Intent intent = getIntents();
String stringToDisplay = null;
if (intent != null)
{
stringToDisplay = intent.getStringExtra (EXTRA_STRING_CONTENT);
}
getIntents will get the Intent object which is created and passed to it by our main activity. getStringExtra is a simple method which says to Android: i want to get the string which is saved with the key EXTRA_STRING_CONTENT (it's something like a Map)
EXTRA_STRING_CONTENT is a field which we used to make sure we don't make any error in passing data, since we need to use the same name when we pass it (in MainActivity) and when we read it (InformationActivity)
public static final String EXTRA_STRING_CONTENT = "EXTRA_STRING_CONTENT";
Ok, we are done.
We now only need to set the string to our TextView:
TextView infoTextView = (TextView) findViewById(R.id.infotextview);
infoTextView.setText (stringToDisplay);
Stop it.
Now we should go to our MainActivity code and modify our addListenerOnButton
final Context context = this;
button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
Intent intent = new Intent(context, MainActivity2.class);
startActivity(intent);
}
});
Well, i will focus on this two lines
Intent intent = new Intent(context, MainActivity2.class);
startActivity(intent);
We need to pass the string to display here, how?
Before we used getStringExtra now it's similar (note: it's the same Intent class) but now we need the putExtra method, the compiler will select the correct overload for us so we just need to do
String stringToDisplay = "Hello world";
intent.putExtra(InformativeActivity.EXTRA_STRING_CONTENT, stringToDisplay);
(Note: InformativeActivity.EXTRA_STRING_CONTENT)
With the current code we will always sent Hello world to the second activity but we need something of dynamic based on the button... well now this depends on how you get the data.
If it's a string-array, you can save the string-array in an array and then based on the button (if it's the first sent string index 0, etc.).
An example:
int buttonId = 1; // it will be a general variable, if it's button 1 it will be 0, if 2-1 etc.
String[] informations = getResources().getStringArray(R.array.infos); // in a real code you should move it outside the `onClick` code and put it in a static final field.
intent.putExtra(InformativeActivity.EXTRA_STRING_CONTENT, informations[buttonId]); // it's the same of above
If you understand the concept you will know how to adapt the code based on your needs.
There are some cases where you need more info or what you want to sent is something which is better if managed by the second activity (example: in a sqlite database you could sent only the id of the line and read lines in the second activity based on this id)
Some things which you could change:
Avoid to call it MainActivity2, it's not so helpful as name
You don't need really to save Context, you could just use MainActivity.this
Try to make your addListenerOnButton more general, example take as argument a Button and set the listener to it.. don't read it from XML you will end up with 180 methods for every button.

SharedPreferences not updating value when returning to Activity, but only keeps initial Activity load value

So I am trying to use SharedPreferences to pass a value from the Activity to a Class. The problem is the following:
On initial loading of the Activity, the value is stored in SharedPreferences but if I exit the Activity and return back, and try to update the value, the SharedPreferences does not seem to update and stays at the value of the initial load of the Activity.
Some class function
private void populatePlayerQueue(){
int category_index;
SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this.getContext());
category_index = sharedPreferences.getInt("selected_category", 0);
}
Activity onResume
#Override
public void onResume() {
super.onResume();
int tmp = Integer.parseInt(getIntent().getStringExtra("CategoryIndex"));
//store the category in the shared preferences
SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.putInt("selected_category", tmp);
editor.commit();
}
What I am trying to do:
I have to send an integer from the activity to a specific class and if I come back to the activity then I need to store the update value and so the class will be able to access the newly updated value again. I only have access to the context and not the activity. This causes errors if I try to create an interface callback to communicate with the activity. So this option is eliminated, hence I am trying anything I can to do that.

For some better result remove the SharedPreference through its key at the time of exit application.
In your case when you exit your application just clear the SharedPreference like:
SharedPreferences.Editor editor = sharedPreferences.edit();
editor.remove("selected_category"); //Just remove it by its specific key
editor.commit();
Then it will clearly load and save the new value again when you go back to your application on the same key or you can use new one.