Develop Reference

Find Id of View in Child Activity

I have an issue , need your help , my question is : I have a multiple activity , so i have created one abstract class which hold the view . Now my question i am able to pass the view to the Base Activity but how to finds view id in Child Activity Class.
I Tried like this :
public abstract class BaseActivity extends Activity {
#Override
protected void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(getLayoutResourceId());
}
public abstract int getLayoutResourceId();
}
My Activity Class:
public class ServiceActivity extends BaseActivity {
Button startSerice_btn, stopService_btn;
MyService myService;
#Override
public int getLayoutResourceId() {
return R.layout.service_xml;
}
}

You can access your views after the super.onCreate() call in the ServiceActivity:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Access them here
}

I think you no need to set content view in BaseActivity like below :
public abstract class MyAppBaseActivity extends AppCompatActivity implements View.OnClickListener {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
}
And you just extends Activity like below :
// for MyCustomActivity1
public class MyCustomActivity1 extends MyAppBaseActivity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
#Override
public void onClick(View view) {
}
}
// for MyCustomActivity2
public class MyCustomActivity2 extends MyAppBaseActivity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
#Override
public void onClick(View view) {
}
}

onClickListener set on Activity

I have a class SomeView that extends View and that is displayed in a class Controls that extends linear layout.
The linear layout is instantiated onCreate of an activity.
I would like to call a method in the activity every time I click on this view SomeView.
I have tried to set an onClickListener in the activity like this
public class MainActivity extends AppCompatActivity implements
SomeView.OnClickListener {
private Controls menu;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
menu = new Controls(this);
menu.getSomeView().setOnClickListener(this);
setContentView(menu);
}
#Override
public void onClick(View view) {
System.out.println("Hello");
}
}
The controls class looks like this
public class Controls extends LinearLayout {
private SomeView aview;
public Controls(Context context) {
super(context);
this.setOrientation(LinearLayout.HORIZONTAL);
aview = new SomeView(context);
this.addView(aview, new LinearLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT));
}
public SomeView getSomeView() {
return aview;
}
}
and the SomeView class looks like this (it just draws an oval)
public class SomeView extends View {
public SomeView(Context context) {
super(context);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
RectF aRect = new RectF();
aRect.left = getPaddingLeft();
aRect.top = getPaddingTop();
aRect.right = getWidth() - getPaddingRight();
aRect.bottom = getHeight() - getPaddingBottom();
Paint aPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
aPaint.setColor(Color.GREEN);
canvas.drawOval(aRect, aPaint);
}
}
But I am missing something because clicks are not calling the onClick method.
What else do I need to set up?

it seems like you did only mistake in your MainActivity class, where you forgot to call the super method. Try doing this, hope it will work, since it works from here in my mobile.
Main Activity
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
menu = new Controls(this);
menu.getSomeView().setOnClickListener(this);
setContentView(menu);
}
And in your callback method, instead using System.out.println(), use Log.d() as below:
#Override
public void onClick(View view) {
Log.d(TAG, "Hello");
}
and it is working from here, look at the image below as well.

Restarting activity inside onClick method

I have an app which reads .txt file and displays contents in table layout.
here is my MainActivity.java file:
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new TableLayout(this,0));
}
}
Inside TableLayout class when adding first row (headers), i also add on click listeners.
Here is the code that gets executed when click happens:
public class MyOnClickListener extends MainActivity implements OnClickListener {
int rowNumber;
public MyOnClickListener(int rowNumber) {
this.rowNumber = rowNumber;
}
#Override
public void onClick(View v) {
setContentView(new TableLayout(context,rowNumber));
}
};
context is saved from when activity is first started, but i get nullpointexception error with this as an argument.
What i would like to do when header is clicked is to recreate table with header number argument.
So my question is what should i do to restart table creation within onClick method?
Edit: this is how context is saved
Context context;
public TableLayout(Context context, int rowNr) {
super(context);
this.context = context;

I would probably do something like this
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new TableLayout(this, getRowNumber()));
}
protected int getRowNumber(){
return 0;
}
}
and then you do something like
public class MyOnClickListener extends MainActivity implements OnClickListener {
// here you initialize rowNumber
static int rowNumber = 0;
#Override
protected void getRowNumber(){
return rowNumber;
}
#Override
public void onClick(View v) {
// here you set your rowNumber
rowNumber = some_value;
recreate();
}
};
P.S: I haven't compiled this but you can get the idea

.Override method of different class

Calling onBackPressed method of Activity class on a View Class? is it possible? and so how can I? thanks for help
UPDATE: I just created the GameView of my Game which is extends to View Class. I create a variable that increments whenever I finish every level so it will limit a levels per game. And so I want to implement a onBackPressed method which I can set the incrementing variable back to zero whenever the player press the back key.
FULL CODE: MAIN ACTIVITY
public class MainActivity extends Activity {
private GameView mGameView;
#Override
public void onBackPressed() {
if (mGameView.interceptBackPressed()) {
return;
}
// TODO Auto-generated method stub
super.onBackPressed();
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.splash);
mGameView = (GameView) findViewById(GameView.countmaze);
Afterwards it goes to Menu Class
public class menu extends Activity implements OnClickListener {
static int nextmaze;
int countmaze = 0;
GameView gameView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button btnplay = (Button) findViewById(R.id.btnPlay);
btnplay.setOnClickListener(this);
}
#Override
public void onBackPressed() {
//I have here an AlertDialog builder
}
#Override
public void onClick(View v) {
case R.id.btnPlay:
Toast.makeText(getApplicationContext(), "LEVEL 1",
Toast.LENGTH_SHORT).show();
startnextmaze();
}
}
void startnextmaze() {
Random rand = new Random();
Intent game = new Intent(menu.this, Game.class);
nextmaze = rand.nextInt(5) + 1;
Maze maze = MazeCreator.getMaze(nextmaze);
game.putExtra("maze", maze);
startActivity(game);
}
Then on my GameView Class
public class GameView extends View {
static int countmaze;
//Big codes here......
public boolean interceptBackPressed() {
// TODO Auto-generated method stub
countmaze = 0;
return true;
}
}

Create a callback on the Activity onBackPressed that the View class will implement
Example
public void interface onBackPressedHandler {
public void onBackPressed();
}
Activity Class
public onBackPressedHandler mHandler;
#Override
public void onCreate(....) {
GameView game... //Inflate or create.
game.setActivity(this);
}
public void setListener(onBackPressedHandler handler) {
mHandler = handler;
}
#Override
public voind onBackPressed() {
if(mHandler != null) {
mHandler.onBackPressed();
}
super.onBackPressed();
View Class
public GameView extends View implements onBackPressedHandler {
public void setActivity(Activity activity) {
activity.setListener(this);
}
public void onBackPressed() {
//your code here.
}
}
This example shows when you press the back Button it will call the onBackPress on the View.
Hope it Helps.

Update your code with the following changes:
Activity
public class MyActivity extends Activity {
private GameView mGameView;
#Override
public void onCreate(Bundle bundle) {
super.onCreate(bundle);
setContentView(R.layout.main);
//View reference to object defined in XML
mGameView = (GameView) findViewById(R.id.gameview);//id must be specified in XML
//I assumed that GameView is a part of your XML layout
//View created programmatically.
mGameView = new GameView(this);
//Use one of the above initialisation techniques of mGameView.
}
#Override
public void onBackPressed() {
//here we are calling method on mGameView which cannot be null
//that's why we initialised it in onCreate() method
if (mGameView.interceptBackPressed()) {
return;
}
super.onBackPressed();//finish your Activity
}
}
GameView
public class GameView extends View {
public boolean interceptBackPressed() {
//TODO handle your game logic here and return true if you don't
//want your game to be shutdown, otherwise return false
return true;
}
}

How can I pass the method from ac Activity to OnClickListener

Hello I have 2 classes for a Memory Game:
One is the NV1 who have the method, for exampe:
public class Nv1 extends Activity{
protected int cardsUp;
protected int currentIndex = -1;
protected int lastIndex = -1;
protected int cardEquals = 0;
protected int lifes = 3;
protected TextView lifes_txt;
protected Handler handler;
protected int [] imgIds = {
R.id.img_1,
R.id.img_2,
R.id.img_3,
R.id.img_4,
};
An another class NVListener that implements OnClickListener.
public class CardsListener implements OnClickListener{
#Override
public void onClick(View v) {
------------
I need to call the method from my Activity to CardsListener. How could I do that?

Method A : Make the listener abstract, implement the abstract method onClick in the Activity
(recommended, listener can be reused easily, easier to debug)
Example:
In SampleActivity.java
public class SampleActivity extends Activity {
Button b;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//Your code here.....
// findViewById()..... etc.
b.setOnClickListener(new SomeListener(){
#Override
public void onClick(View v) {
someMethod();
}
});
}
public void someMethod(){
Log.d("Log Tag","Some Message");
}
}
In SomeListener.Java
//make it abstract
public abstract class SomeListener implements OnClickListener{
//put your own method,variables inside
//do not override onClick()
}
Method B : Create a constructor with the Activity as a input parameter. Save the activity instance and call its method freely (less recommended : not flexible, and not logical IMO)
In SomeListener.Java
public class SomeListener implements OnClickListener {
private SampleActivity mAct;
public SomeListener(SampleActivity act){
mAct = act;
}
#Override
public void onClick(View v) {
mAct.someMethod();
}
}