Develop Reference

How can i set custom theme for whole application at run time on single click?

How to change the theme without recalling activity?
Suppose I have two activities A and B. I am calling activity B from activity A. From activity B I am changing the theme and by doing recreate() activity B's theme gets changed. But how can I change the theme of activity A that is in the back stack?
I don't want to recall activity A from activity B.

The issue here is when you go back from your Activity B to Activity A this last one will get resumed. So in the onResume method you will need to check if the theme as changed and apply it to your activity.
Here is an example:
public class BaseActivity extends AppCompatActivity {
private int mTheme;
#Override
protected void onCreate(Bundle savedInstanceState) {
mTheme = getCurrentTheme();
setTheme(mTheme);
super.onCreate(savedInstanceState);
}
#Override
protected void onResume() {
super.onResume();
int currentTheme = getCurrentTheme();
// If the theme has changed, we need to apply it
if (mTheme != currentTheme) {
// Recreate activity
Intent intent = getIntent();
finish();
startActivity(intent);
}
}
}

How to prevent the Screentshot in the entire android app without repeating the same code

Hi everyone i want to block the Screenshot in my app. I got the first problem solve from here.
But now the thing is I have more than 10 activity and 10 + fragment.
Is there any way to do this just by writing in the one class and giving it reference to the entire app.
Just like we make one Application class and in the AndroidMainfest.xml give that application class refrence.

You can implement a BaseActivity, and make all your activities extend this BaseActivity. In onCreate() of this activity set the flag. You need to ensure all your activities call super.onCreate() as follows:
BaseActivity.java
public abstract class BaseActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//set your flag here
...
}
}
Activity1.java
public class Activity1 extends BaseActivity{
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
...
}
}

Android Destroy current view from parent

I have a Parent activity that sets a view on Resume based on some check like this :
public class AppLockActivity extends AppCompatActivity {
#BindView(R.id.btnSubmit)
Button submitButton;
private static final String TAG = "AppLockActivity";
private static TimeElapsed timeElapsedInstance;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
timeElapsedInstance = TimeElapsed.getInstance();
timeElapsedInstance.resetTime();
timeElapsedInstance.setStartTime();
}
#Override
protected void onResume() {
super.onResume();
//check if app has passed a time threshold
if(timeElapsedInstance.getStartTime() != 0){
timeElapsedInstance.setEndTime(Calendar.getInstance().getTimeInMillis());
long threshold = timeElapsedInstance.getEndTime()-timeElapsedInstance.getStartTime();
Log.d(TAG,"Threshold : "+threshold);
//Current timeout threshold set to 30s
if(threshold>30000){
setContentView(R.layout.activity_app_lock);
ButterKnife.bind(this);
}else{
}
}
}
#OnClick(R.id.btnSubmit) void onSubmit() {
//destroy current(Parent) view and show the previous
}
}
This activity is extended by other activities like MainAcitivty ,etc...
public class MainActivity extends AppLockActivity{
#Override
protected void onCreate(Bundle savedInstanceState) {
setContentView(R.layout.activity_main);
}
}
When the app goes in background and is resumed the onResume function is called and based on the check the new View is set - R.layout.activity_app_lock. What I want to do is onClick of the submit button in this view I want to destroy the current view i.e (R.layout.activity_app_lock) and show the previous view that was in the child activity like MainActivity (R.layout.activiyt_main)...
Anybody have any idea how can I do this?
Thanks

You can actually call setContentView again with a different view. All your bindings need to be reset and your On_____Listeners need to be cleared or else you'll get a memory leak. Other than that, it'll be up and ready for you to go.
Though I suggest an alternative approach to changing the layout. Instead, create a new Activity that you start in replacement of the layout your currently submitting. Then, rather than worrying about leaks, you just call finish() on the lock Activity when the user submits. The effect would be the same and it would be more versatile (In my opinion).

Android application closes on click

I do my android app , but I have a bug I don't know how to fix it.
My code is below :
This is my Main Activity :
public class MainActivity extends Activity {
private ImageView imgHot;
public final static String EXTRA_MESSAGE="com.cuonglm.KhoHinh.MESSAGE";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
imgHot=(ImageView)findViewById(R.id.imageViewHot);
imgHot.setOnClickListener(toContentHot);
}
View.OnClickListener toContentHot=new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent content=new Intent(MainActivity.this,ContentActivity.class);
String signal="1";
content.putExtra(EXTRA_MESSAGE,signal);
startActivity(content);
}
};
And this is my second Activity :
public class ContentActivity extends Activity {
private TextView viewMessage;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Intent content=getIntent();
String messageReceive=content.getStringExtra(MainActivity.EXTRA_MESSAGE);
viewMessage=(TextView)findViewById(R.id.content_receive);
viewMessage.setText(messageReceive);
setContentView(R.layout.activity_content);
}
I want to click on the image on the Main Activity , string "1" or number "1" will send to the Second Activity via Intent and view on the TextView.
But my app will be close "Unfortunately..."
Thanks

Change to
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_content);
viewMessage=(TextView)findViewById(R.id.content_receive);
viewMessage.setText(messageReceive);
In your ContentActivity
findViewById looks for a view with the id for the current infalted layout. SO you need to set the content of your layout to the activity first and then initialize your views.
You are probably gettting NullPointerException coz your initialization fails.

You need to call setContentView() in your second Activity before trying to access any of the Views in that layout. Change it to
public class ContentActivity extends Activity {
private TextView viewMessage;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_content);
Intent content=getIntent();
String messageReceive=content.getStringExtra(MainActivity.EXTRA_MESSAGE);
viewMessage=(TextView)findViewById(R.id.content_receive);
viewMessage.setText(messageReceive);
}
If this doesn't fix your problem then please post your logcat so we can see the error. Also always post logcat in the future when your app crashes. They aren't always this easy to see.
Also, I'm not sure you understand how putExtra() works. It is a key, value pair so when you put EXTRA_MESSAGE as the key then that is what you would use to retrieve the value added in the second param. So the way you are doing it may work if the Activity gets destroyed but it looks really strange to me and probably not realy safe or efficient. I would change it to something like
content.putExtra("message",signal);
in your first Activity then get it with
String messageReceive = content.getStringExtra("message");
in your second Activity

You need to set the layout before trying to reference the Views associated with it.
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Intent content=getIntent();
String messageReceive=content.getStringExtra(MainActivity.EXTRA_MESSAGE);
setContentView(R.layout.activity_content);
viewMessage=(TextView)findViewById(R.id.content_receive);
viewMessage.setText(messageReceive);
}

How do we get the theme of an Activity?

I am trying to detect the theme used for an activity but so far I am only able to find that out for the entire application? Is there a way to do this?

Just call the method getTheme() in your activity. For example.
public class MainActivity extends PreferenceActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Theme theme = this.getTheme();
}
}

My first thought would be ContextThemeWrapper.getTheme(), since Activity extends ContextThemeWrapper