Question

I’m a novice programmer and I’m trying to learn Android coding using Eclipse.
This is my first time using StackOverflow.

Just for tutorial purposes, I want to make a simple Animal Encyclopedia.

So in my Home class, there are some buttons: “Dog”, “Cat”, “Bird”, etc. When I click the button, it will bring me to the same layout but of course with different content.

• So I created a class named AnimalData that holds the
  ArrayList<Integer> to store R.drawable.xxx and ArrayList<String>
  to store the text that I will put below the picture (like “Bulldog”
  or “Husky”)

• Then I created a class named ChangeContent to set all those drawable
  and text to the XML

• But whenever I click the button, it results in Stopped Unexpectedly Error

Below are the shortened Home class, The “crash-maker” isn’t here. I have checked the whole code line per line using Thread.sleep(2000), so if my app crashes before 2 second, the error is before the sleep() code and vice versa.

public class Home extends Activity implements OnClickListener{
    Button dog, cat, bird;
    AnimalData ad;
    ChangeContent cc;

    private ArrayList<Integer> drawable;
    private ArrayList<String> title;

public Home(){
    ad = new AnimalData();
    cc = new ChangeContent(ad);
    drawable = new ArrayList<Integer>();
    title = new ArrayList<String>()
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.home);
    //set the findViewById for all the buttons
    //set onClickListener() to all the buttons
}

public void onClick(View v) {
    switch (v.getId()){
    case R.id.bDog:
        drawable.add(R.drawable.xxx);
        drawable.add(R.drawable.yyy);
        title.add("Bulldog");
        title.add("Husky");
        break;
    case R.id.Cat:
        //same
        break;
    case R.id.bBird:
        //same
        break;
    }
    ad.setDrawable(drawable);
    ad.setTitle(title);
    Intent i = new Intent("animal.ChangeContent"); //from Manifest
    startActivity(i);
}
}

The AnimalData is just a typical getter setter, so I will just skip the code for that

The error is right after ChangeContent started because even when I put the sleep() on the first line of constructor, it doesn’t have any effect.

public class ChangeContent extends Activity {

    TextView title1, title2;
    ImageView pic1, pic2;
    private ArrayList<Integer> drawable;
    private ArrayList<String> title;

public ChangeContent(AnimalData data){
    drawable = new ArrayList<Integer>();
    title = new ArrayList<String>();
    drawable = data.getDrawable();
    title = data.getTitle();
}
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.animal_info);

    //findViewById for the TextView and ImageView
    //setText() for TextView and setImageResource() for ImageView
}
}

Sorry for the long question, I tried to make it as short as possible
Can you guys help me figure the error out?
Thanks before

Answer 1

You are trying to get arraylist from intent, whereas you are not putting putStringArrayList and putIntegerArrayList methods.

putIntegerArrayListExtra(String name, ArrayList<Integer> value)

putStringArrayListExtra(String name, ArrayList<String> value)

so Change calling activity to following:

Intent i = new Intent(Home.this, ChangeContent.class); //from Manifest
i.putIntegerArrayListExtra("drawables", drawable);
i.putStringArrayListExtra("titles", titles);
startActivity(i);

and get data from intent in onCreate method by following methods:
getIntegerArrayListExtra, and getStringArrayListExtra

you also can do following by making contentChanged method to static, by this you wont need to do much changes in your application code, just do following:

public class ChangeContent extends Activity {

    TextView title1, title2;
    ImageView pic1, pic2;
    private static ArrayList<Integer> drawable;
    private static ArrayList<String> title;

public static ChangeContent(AnimalData data){
    drawable = new ArrayList<Integer>();
    title = new ArrayList<String>();
    drawable = data.getDrawable();
    title = data.getTitle();
}
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.animal_info);

    //findViewById for the TextView and ImageView
    //setText() for TextView and setImageResource() for ImageView
}
}