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Simple increment counter doesn't work in android app

sounds stupid but a simple increment counter doesn't work in my android app.
I have two activities in the app and one counter in each, which is incremented each time when onCreate method is called. When I'm switching between the activities the first one works well, but the other one just doesn't count.
I'm using the same line to create the variable like this:
private int mCreate;
Then I'm just incrementing it in the same way in each class in the onCreate method:
mCreate++;
This variable is used in two different classes, so it shouldn't be a problem. This is my first android app, so I need some help.
The whole code of the second activity. I'm not showing the first one because the only difference is in the setOnClickListener method.
public class ActivityTwo extends Activity {
private final static String TAG = "Lab-ActivityTwo";
private int mCreate;
private TextView mTvCreate;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_two);
mTvCreate = (TextView) findViewById(R.id.create);
Button closeButton = (Button) findViewById(R.id.bClose);
closeButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
finish();
}
});
}
Log.i(TAG, "Entered the onCreate() method"); // to check if the inCreate method was called
mCreate++;
mTvCreate.setText("onCreate() calls: " + mCreate);
Log.i(TAG, "mCreate = " + mCreate); // just to check if I implemented the TextView worng
displayCounts();
}

The reason your second counter doesn't work because after finishing an activity all the variables and objects are destroyed and make free by GC. The next time you call for that activity it is created from scratch and your count remain same everytime.
Like #Opoo said if you want to get count you should define static variable in Application class.

Using static methods in Android?

I already made some Apps in Android and noticed that I am often using static methods.
For example I have an Class which extends PreferenceFragment. In this PreferenceFragment I set an onClick event on a Button.
Button btn = new Button(getActivity().getApplicationContext());
btn.setText("Save");
v.addView(btn);
btn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
SettingsActivity.finishActivityWithResultOkey();
}
});
Then I'm calling a static method in my SettingsActivity which finishes this Activity. Is this a good way of doing what I want to do? Or is there a better solution?

In Android (in memory managed programming languages like Java, more precisely), static methods can lead to "memory leaks" if not used correctly. I've quoted "memory leaks" as they are not the pure definition of memory leaks, like in C++ where you forget to remove some items from memory and lose the reference to them (and thus cannot clear them later on - at least not easily), but more like keeping on to references when you no longer need them and preventing the GC from doing its job in clearing that memory for you. There are a lot of articles on the web that cover this (search for "Android static memory leak") and a lot of other questions on SO that have been asked about this (see [static][Android][memory-leaks] tags), so I won't go into this.
For your particular case, in order to avoid possible memory leaks, you can get the Activity from the Fragment object that your anonymous OnClickListener object is tied to by using MyFragmentClass.this.getActivity(), cast it to, say, SettingsActivity (as is the case here) and call .finishActivityWithResultOkey() on it. It's best that you guard your cast too.
Here's an example of how the code could look like:
btn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
final Activity activity = MyFragmentClass.this.getActivity();
if(activity instanceof SettingsActivity)
((SettingsActivity)activity).finishActivityWithResultOkey();
else
throw new IllegalStateException("This OnClickListener requires a SettingsActivity to start the fragment containig it"); //helps with debugging
}
});
As a note: MyFragmentClass refers to the class of the fragment that you're putting this code in :)

You can use a Java property known as mirroring.
Below I use the property to finish the activity.
Button btn = new Button(getActivity().getApplicationContext());
btn.setText("Save");
v.addView(btn);
btn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
SettingsFragment.this.getActivity().finish();
}
});

query about View.OnClickListener() in android

I'm trying to understand what is View.OnClickListener().
I have read this site: http://developer.android.com/reference/android/view/View.html, but I cannot understand who is the client and who is the listener.
Please explain in details. Thanks in advance.

From docs:
Interface definition for a callback to be invoked when a view is
clicked.
reference
Simply said: So when you implement this, you are able to handle click events for your Views - all widgets as Button, ImageView etc..
When you implement this you have to implement onClick method. When you click on some View, this method is immediately called.
public void onClick(View v) {
switch(v.getId()) {
// do your work
}
}
But don't forget that you have to register your OnClickListener for specific widget
someButton.setOnClickListener(this);
Most likely you need to learn Android basics and i recommend it to you.
Note: You can use Listeners also as anonymous classes

This is an Interface to implement for classes which want to get a notification if a View element got clicked.
For instance:
public class FooActivity extends Activity implements View.OnClickListener {
public void onCreate(...) {
View v = findViewById(...);
v.setOnClickListener(this);
}
public void onClick(View v) {
// method which is invoked when the specific view was clicked
}
}

Android: Call listener manually from java code

Is there any way to call a listener manually from code?
More background information: I use a Spinner and a DatePicker. With the Spinner you can choose a reason for staying at home (maybe your ill, maybe you have vacation) and with the DatePicker you can choose the date how long you will not be available. With these two pieces of information I build up a string for a TextView and show the same data in a compact way. The building process for the string is set by some listeners which recognize changes on one of the two controls and build and set up the new string.
If I start the program and read some data from a server the string will not be build (clearly because nothing changed and no listener will called).
The workaround is to build the string in my own onLoaddata() method. But I think it would be smoother way to call one listener to build the string for me. I also can "call" a listener if I just do some fake .updateDate but I don't think it’s a good idea to create useless calls...
Maybe someone of you have a good hint for me?

Use the following pattern:
public class YourActivity extends Activity implements OnClickListener {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
...
// Some initialization here
findViewById(R.id.some_button).setOnClickListener(this);
...
// Here you want to update your view
updateTextView();
}
#Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.some_button:
// Here you also want to update your view
updateTextView();
break;
...
}
}
private void updateTextView() {
// Here you update your view
...
}
}

Android (student cw) in need of direction

public class Menu extends Activity {
/** Called when the activity is first created. */
public void onCreate(Bundle icicle) {
//myIntent.setClassName("hello.World", "hello.World.mybuttonclick");
// myIntent.putExtra("com.android.samples.SpecialValue", "Hello, Joe!"); // key/value pair, where key needs current package prefix.
//startActivity(myIntent);
//Button myButton = (Button) findViewById(R.id.my_button);
super.onCreate(icicle);
setContentView(R.layout.main);
}
public void updateLayout(){
Intent myIntent = new Intent(Menu.this, mybuttonclick.class);
startActivity(myIntent);
// TextView sayHello = (TextView) findViewById(R.id.Hello);
}
}
Hey guys, I am a new android java student and we have to develop a simple hello world app.. I am finding some difficulty getting my onClick() activity to work, using android:Onclick in xml.. what i am trying to do is change the content view do display a simply a different layout and saying hello.. i am using setContentLayout to do this, every time i click said button tho the android app crashes out.. am i doing something wrong?
regards,
Stefan

When you set a click listener in xml you must have the method defined inside the activity you are clicking in. Lets say you set the onClick in xml to be "buttonClicked", you must create a method looking exactly like the one below.
public void buttonClicked(View view)
{
//Your code here
}
The thing to notice is that the method is a public void with only a single parameter of type View. XML defined click listeners must be like this to work. The view object in the example above is the view that was clicked.

You update layout function needs to read
public void updateLayout(View view)

In response to your question, there are a number of things that are issues causing the complication that you described. Let it first be said, that you don't have to do anything any particular way, provided that you make concessions for certain things. Android is a very flexible platform and Java, as an OOP language allows you to do things that many non OOP languages do not.
Whenever you create a "clickable" item, like a Button, if you want to have your program respond, you must have something "listen" to it. This is known as a Listener. In your case, you are looking for an OnClickListener. The OnClickListener does not have to be a part of the Activity necessarily. It just has to be a class that implements View.OnClickListener. Then, you have tell the setOnClickListener() method of the Button who its listener is. The following example shows what is necessary without your declaration in XML (but it is important).
class Menu extends Activity implements View.OnClickListener
{
public void onCreate(Bundle icicle)
{ setContentView(R.layout.main);
Button btn = (Button)findViewById(R.id.BUTTON_ID_AS_DEFINED_BY_YOUR_XML);
btn.setOnClickListener(this);
}
public void onClick(View view)
{ int id = view.getId();
if (id == R.id.BUTTON_ID_AS_DEFINED_BY_YOUR_XML)
updateLayout()//Do your Click event here
}
public void updateLayout()
{ //updateLayout code...
}
}
Something that needs to be noted is the OnClick() above. Every OnClickListener must use the same signature as theOnClick() That means itmust have the same return and same arguments even if it has a different name. For what you are trying to do (in XML), you have set your android:OnClick to updateLayout. This means that `updateLayout() must be declared as follows:
public void updateLayout(View view)
Now, getting the update method to actually work: While you provide your code, we don't actually know what errors you are getting. It is always much easier to solve a problem if we have a copy of the Logcat output that includes the error you are receiving. Once, we have that we can target your error specifically and I can edit my answer to include what you may additionally need.
FuzzicalLogic