Crash starting new activity? (Intent)

Question

this is the code of my two activty

this app by the clicking one of the buttons of Activity A, in the Activity B should show a listview with the names specified in the command switch (v.getId ()) in the activity A, and if you click on one of those names should always leave the url below: in the same command of Activity A

But as soon as I click on one of the buttons the app crashes, i don't know how to solve

Activity A

 public class GruppiPuntateActivity extends ActionBarActivity implements         OnClickListener {

ArrayList<String> bottone;
Button b1,b2,b3,b4,b5,b6,b7,b8,b9,b10;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    //creazione fullscreen activity
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
    WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.gruppipuntate_activity);

    //rimozione action bar
    if (Build.VERSION.SDK_INT < 11){
        getSupportActionBar().hide();

        b1 = (Button) findViewById (R.id.button1);
        b2 = (Button) findViewById (R.id.button2);
        b3 = (Button) findViewById (R.id.button3);
        b4 = (Button) findViewById (R.id.button4);
        b5 = (Button) findViewById (R.id.button5);
        b6 = (Button) findViewById (R.id.button6);
        b7 = (Button) findViewById (R.id.button7);
        b8 = (Button) findViewById (R.id.button8);
        b9 = (Button) findViewById (R.id.button9);
        b10 = (Button) findViewById (R.id.button10);
        b1.setOnClickListener(this);
        b2.setOnClickListener(this);
        b3.setOnClickListener(this);
        b4.setOnClickListener(this);
        b5.setOnClickListener(this);
        b6.setOnClickListener(this);
        b7.setOnClickListener(this);
        b8.setOnClickListener(this);
        b9.setOnClickListener(this);
        b10.setOnClickListener(this);
    }

 }
    //gestione Switch java per selezione puntate
    public void onClick(View v) {
        String[] product;
        String[] urls;

        Intent episodi = new Intent(GruppiPuntateActivity.this, EpisodiActivity.class);

         switch(v.getId()){ 
         case R.id.button1:
             product = new String[]{"ciao", "1", "bottone"};
             urls = new String[] {"http://www.dailymotion.com/video/x21cxmf_camera-cafe-3-stagione-ep-252-un-cane-per-amico_shortfilms, url2, url3"};
             episodi.putExtra("Product", product);
             episodi.putExtra("urls", urls);
             startActivity(episodi);
             break;
         case R.id.button2:
             product = new String[]{"ciao", "1", "bottone"};
             urls = new String[] {"url1, http://www.dailymotion.com/video/x21cxmf_camera-cafe-3-stagione-ep-252-un-cane-per-amico_shortfilms, url3"};
             episodi.putExtra("Product", product);
             episodi.putExtra("urls", urls);
             startActivity(episodi);
             break;
        //etc.etc....
         }
    }

}

Activity B

  public class EpisodiActivity extends Activity {


String[] episodi = getIntent().getStringArrayExtra("Product");
String[] urls = getIntent().getStringArrayExtra("urls");


public class ViewModel {
    private String url;
    private String name;

    public ViewModel(String url, String name) {
        this.url = url;
        this.name = name;
    }

    public String getUrl() {
        return this.url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public String getName() {
        return this.name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String toString() {
        return this.name;
    }
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    //creazione fullscreen activity
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
    WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.episodi_activity);

    ListView mylist = (ListView) findViewById(R.id.listView1);

    // And in this loop we create the ViewModel instances from 
    // the name and url and add them all to a List
    List<ViewModel> models = new ArrayList<ViewModel>();
    for (int i = 0; i < episodi.length; i++) {
        String name = episodi[i];
        String url = urls[i];
        ViewModel model = new ViewModel(name, url);
        models.add(model);
    }


    // Here we create the ArrayAdapter and assign it to the ListView
    // We pass the List of ViewModel instances into the ArrayAdapter
    final ArrayAdapter<ViewModel> adapter = new ArrayAdapter<ViewModel>(this, android.R.layout.simple_list_item_1, models);

    mylist.setAdapter(adapter);


    mylist.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        public void onItemClick(AdapterView<?> arg0, View v, int position, long id) {

            // Here we get the ViewModel at the given position
            ViewModel model = (ViewModel) arg0.getItemAtPosition(position);

            // And the url from the ViewModel
            String url = model.getUrl();

            startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(url)));
        }
    });
}

}

Answer 1

  if (Build.VERSION.SDK_INT < 11)

all your buttons are initialized only for devices with Api level less than 11

if you click any button on Device with APi level 11 and Above youll get error.

Update :

  if (Build.VERSION.SDK_INT < 11){
     getSupportActionBar().hide();
        }
  // Make Button initialization outside if loop  and your app will work

Answer 2

Firts, you should always look in your LogCat, to look what error is thrown.

Second, on your buttons, you have

//rimozione action bar
if (Build.VERSION.SDK_INT < 11){
    getSupportActionBar().hide();

    b1 = (Button) findViewById (R.id.button1);
    b2 = (Button) findViewById (R.id.button2);
    ...
    b1.setOnclickListener(this);
    b2.setOnClickListener(this);
    ...
}

The code runs olny, when the SDK is smaller then 11. Want to function your buttons everytime, so do this

//rimozione action bar
if (Build.VERSION.SDK_INT < 11){
    getSupportActionBar().hide();

}
b1 = (Button) findViewById (R.id.button1);
b2 = (Button) findViewById (R.id.button2);
...
b1.setOnclickListener(this);
b2.setOnClickListener(this);
...

And then, on the button, zou call setOnClickListener, which allows you to handle click events. But you have to pass a new OnClickListener object, to let it work. look at the official example here .

In you case, its gonna be like this:

b1.setOnclickListener(new View.OnClickListener() {
    public void onClick(View v) {
        // Do something in response to button click
   }
});

I hope this helps.

Answer 3

This declarations

String[] episodi = getIntent().getStringArrayExtra("Product");
String[] urls = getIntent().getStringArrayExtra("urls");

Are bad because you are not loading yet the activity to get information from that, you need initialize this variables after, in your onCreate(), onResume or onStart() methods

String[] episodi;//Correction
String[] urls;//Correction
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    //creazione fullscreen activity
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
    WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.episodi_activity);
    episodi = getIntent().getStringArrayExtra("Product"); ////Line added
    urls = getIntent().getStringArrayExtra("urls");////Line added
    ListView mylist = (ListView) findViewById(R.id.listView1);
.......
    }

Now the best thing that you can do is a validation for this variables

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    //creazione fullscreen activity
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
    WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.episodi_activity);
    episodi = getIntent().getStringArrayExtra("Product"); ////Line added
    urls = getIntent().getStringArrayExtra("urls");////Line added
    if (episodi == null) { ////Validation
         Log.d("NULL", "episodi is null");
         return;
    }
    if (urls == null) { ////Validation
         Log.d("NULL", "urls is null");
         return;
    ]
    ListView mylist = (ListView) findViewById(R.id.listView1);
.......
    }

Answer 4

put these lines in the onCreate method

String[] episodi = getIntent().getStringArrayExtra("Product");
String[] urls = getIntent().getStringArrayExtra("urls");