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Android - Calling an ordinary object method from an activity

First, I am an android rookie, so my solution ways can be found awkward, and i am open to suggestions.
I am trying to create a game manager object that handles all transitions between activities. And my purpose is that while in an activity, menuOut method will call the changeActivity method of GameManager object with nextActivity argument and changeActivity will start that Activity. I am getting errors consistently, and did not find a solution.
Here is my source codes:
GameManager:
public class GameManager{
public SplashScreen splash = new SplashScreen();
public MainScreen main = new MainScreen();
public LoadingScreen load = new LoadingScreen();
Context tempContext;
public GameManager(Context base) {
super();
tempContext = base;
}
public void start(){
createScreens();
Intent intent = new Intent(tempContext, splash.getClass());
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
tempContext.startActivity(intent);
}
public void createScreens() {
//here is the method that i am trying to find a solution
((SplashScreen)splash.getContext()).setGameClass(this);
((MainScreen)main.getContext()).setGameClass(this);
((LoadingScreen)load.getContext()).setGameClass(this);
}
public void changeMenu(MenuType nextMenu, MenuType previousMenu){
Intent intent2;
switch(nextMenu){
case MAIN_SC:
tempContext = main.getContext();
intent2.setClass(tempContext, main.getClass());
intent2.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
tempContext.startActivity(intent2);
case GAME_LOADING_SC:
tempContext = load.getContext();
intent2.setClass(tempContext, load.getClass());
intent2.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
tempContext.startActivity(intent2);
default:
break;
}
}
}
And here is SplashScreen activity:
public class SplashScreen extends Activity {
public Context context = this;
public GameManager gameman;
private static final int SPLASH_DURATION = 4000;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
splash();
menuOut();
}
public Context getContext() {
return this;
}
public void splash() {
LinearLayout ll = new LinearLayout(this);
ll.setOrientation(LinearLayout.HORIZONTAL);
ll.setBackgroundResource(R.drawable.game_loop_splash);
setContentView(ll);
Handler handler = new Handler();
// run a thread after 2 seconds to start the home screen
handler.postDelayed(new Runnable() {
#Override
public void run() {
finish();
}
}, SPLASH_DURATION);
}
public void setGameClass(GameManager game){
gameman = game;
}
private void menuOut(){
gameman.changeMenu(MenuType.GAME_LOADING_SC, MenuType.GAME_SPLASH_SC);
this.onDestroy();
}
}
I can not return to the GameManager and call the changeMenu method.
I am very exhausted to get null pointer exceptions.
Any idea?

From what I read, you are trying to implement a singleton pattern. There are two ways I'd recommend to do that on android:
Extend the Application class, register your class in the manifest and use getApplication() in your activities to get access to it:
// In MyApplicationSubclass.java:
public final class MyApplicationSubclass extends Application {
/* ... */
public void myMethod() {
// insert some code here
}
/* ... */
}
// From your Activity:
((MyApplicationSubclass) this.getApplication()).myMethod();
Use a "normal" java singleton pattern, e.g. use a private constructor and keep one static instance within your GameManager class (this is the way the Android docs recommend, but I personally prefer the first way when having something that is logically bound to the Application).
Also, if you're only using your central class to do static stuff, you can just mark all its method as static and access them directly. Transfer Context objects as parameters to these methods, and you should be able to start activities without any static variables (which are sometimes hard to implement properly in Android, as your VM might get restarted from time to time).

Android: using getIntent() only within onCreate?

In Android (targeting APIs 14-16) I have a MainActivity and a NextActivity. There is no difficulty using intents to start NextActivity from within MainActivity if the getIntent() method is called inside the onCreate() block of NextActivity:
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
int data = 7;
...
Intent intent = new Intent(this, NextActivity.class);
intent.putExtra("data", data);
startActivity(intent);
}
}
public class NextActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
final int data = this.getIntent().getIntExtra("data", 7);
...
}
...
}
However, since the field data is being used inside an anonymous ("inner") class in NextActivity, I am compelled to declare it final.
I'd prefer not to declare fields final, and I can usually avoid doing so if I declare them at the beginning of the class, before onCreate() begins. But for some reason, the app crashes when NextActivity starts if the getIntent() statement appears (without the final keyword) outside of onCreate().
Any idea why?

You can't getIntent() before onCreate() -- there's simply no Intent available at that point. I believe the same is true for anything that requires a Context.
Your anonymous inner class can still call getIntent(), however, so you don't need to declare this as a variable at all.

According to your question what i understand is u don't want to declare data as final in next activity..Then y cant u try for this./
public class NextActivity extends Activity {
int data=0;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
data = this.getIntent().getIntExtra("data", 7);
...
}
...
}
Try this...

pass UI Controls from activity to a class

I stuck at this issue many times and I passed the problem in different ways and I'm not sure that I made it in the right way.
I simplified the problem in a the following example. I know that I can pass only the data to the class but I do want to pass the editText cause I have this problem with more difficult UI controls.
mainactivity.java
public class mainactivity extends Activity {
public EditText clickEditText;
int count =0;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
newTxt();
}
public void newTxt() {
txt = new MyText(context);
txt.updateTextEdit("Main Activity");
}
}
myText.java
public class MyText
{
private Context _context;
// constructor
public MyText(Context context)
{
_context = context;
}
public void updateTextEdit(String str)
{
private EditText strEditText;
strEditText= (EditText)findViewById(_context.R.id.editTextClick); // ????
strEditText.setText(str + " and myTxt");
}
}
if you could explain me how to fix the updateTextEdit function. i passed the context of the main activity. How can I change the editText? Thank you very much!!!

If you really want to do this this way, you need to save a reference to Activity, not Context. Like this:
public class MyText
{
private Activity _activity;
// constructor
public MyText(Activity activity)
{
_activity= activity;
}
public void updateTextEdit(String str)
{
private EditText strEditText;
strEditText= (EditText)activity.findViewById(R.id.editTextClick);
strEditText.setText(str + " and myTxt");
}
}
and in newTxt() you will need to change:
txt = new MyText(context);
to:
txt = new MyText(this);
But wouldn't it be easier to just put this method inside your activity? Why do you want it in another class? If it really needs to be in another class, you could make that class an inner class of your activity and you would still have access to the activity's methods and member variables.

There's a similar question here
How to access Activity UI from my class?
You didn't say how you obtained the context, you should use this and get the mainactivity in the other class. not context.
then you can call runOnUIThread to perform UI updates.

Share the object on real-time, singeltond pattern

I simply have not found a solution to share a real-time data between the activitys. My first activity receives real-time object (type double, a random numbers). And i want to pas this numbers to second activity. It all works, only the second Activity shows only one time the data. I have to refresh the activity by going back to first activity and only then the second activity show the latest data. I implemented a Singelton pattern:
public class FirstActivity extends Activity{
public double xAxis;
public double yAxis;
public static FirstView instance;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.device_view);
handler = new Handler() {
#Override
public void handleMessage(Message msg) {
int data1 = msg.arg1;
xAxis = (double) data1;
dataX.setText(String.valueOf(xAxis));
int data2 = msg.arg2;
yAxis = (double) data2;
dataY.setText(String.valueOf(yAxis));
}
};
secondview.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Intent nextScreen = new Intent(getApplicationContext(),
SecondActivity.class);
startActivity(nextScreen);
}
});
}
public static void initInstance(){
if(instance == null)
{
instance = new FirstActivity();
}
}
public static FirstActivity getInstance(){
return instance;
}
}
SecondView class
public class SecondActivity extends Activity{
private double valueX;
private double valueY;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.linegraph);
valueX = FirstActivity.getInstance().xAxis;
valueY = FirstActivity.getInstance().yAxis;
}
}
Application class
package com.bluetoothcomm;
import android.app.Application;
public class MyApplication extends Application {
#Override
public void onCreate(){
super.onCreate();
initSingeltons();
}
public void initSingeltons(){
FirstActivity.initInstance();
}
}

You may implement a background service capable of providing the real time data to Activity1 and also to Activity2. I am guessing that your problem ocurrs if you are passing data from Activity1 to Activity2 through an Intent with putExtras, on this way it will only do this at the moment you start Activity2.

I have found my problem and the solution is to use Application. Only this dose not solves my problem. The problem is that the static variable instance public static FirstView instance is bound to the class loader, the first class that initilize that. So when the static variable inside any class has been initilized by an Activity and when the second Activity is started the first Activity is destroyed, so this means the static variable is also uninitilized. Thats why the SecondActivity dose not gets the up to date data or real time data, it catches only static constant data.
I changed my code a littele bit with the combination of Singelton and Application, couse this way the static variable should never be uninitilized when SecondActivity is activated. But i still get the same results, the static variable instance is uninitilized when i swtich to Second Activity. I am doing somethink wrong, does any one sees it. I added my code.
#Max Rasguido, #Orabig

You should use the intent process. docs

How is your data supposed to change when activity2 is shown, if you say that it's received by activity1 ?
However, I would use a preference, or an attribute of your application class (which is a singleton itself), but you give too little informations to fully understand your needs...

How to pass BroadcastReceiver content to an Activity within same Java class

i working on a custom dailer. So far i am able make the user select the dailer he wants to use but when he chooses my dailer the number he wants to call is not dailed; instead my activity is shown.
I want it to show make the call based on the selected number and show my activity.
public class myActivity extends TabsActivity {
private OneActivity bb;
private String oldNumber2;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
class OneActivity extends BroadcastReceiver {
public void onReceive(Context context, Intent intent) {
final String Number1 = intent.getStringExtra(Intent.EXTRA_PHONE_NUMBER);
Toast.makeText(context, Number1, Toast.LENGTH_LONG).show();
Intent dial = new Intent(Intent.ACTION_CALL,Uri.parse("tel:" + Number1));
launch.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(dial);
}
}
When i checked the log, i found that the phone number is loaded into the BoradcastReceiver but not dailed out. Please Help

Try this
Intent dial = new Intent(Intent.ACTION_CALL,Uri.parse("tel:" + Number1));
dial.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(dial);
Add the following to manifest
<uses-permission android:name = "android.permission.CALL_PHONE"/>

you can use setter/getter methods for such purpose.
see this example, first create a separate class file
public class passData
{
private String number;
public void setNumber ( String number )
{
this.number = number;
}
public String getNumber ()
{
return number;
}
}
Now you need to set your Number1 variable in to this class's method using set method, and you can get its value in to any other class or in activity, from whole project.