Android: Passing extra from one activity to another activity

I have a JSON file which is populated to an activity (Main.java).

This Activity shows 3 random images from the URL on my JSON entries.

What I wanna do is: I have 13 different entries on the my JSON, whenever I click the shown random picture it goes to another activity (ProjectDetail.java) containing the picture,title,and description depends on the item I click based on its entry on the JSON.

What do I have in is by using extra by I dont know exactly how to perform that since I'm using JSON. What should I add into my top_listener method on my Main class and what should I add into my ProjectDetail class?

Thank you.

Main.java

   public class Main extends Activity {
            /** Called when the activity is first created. */

            ArrayList<Project> prjcts=null;
            private ImageThreadLoader imageLoader = new ImageThreadLoader();
            private final static String TAG = "MediaItemAdapter";


            @Override
            public void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.main);

                prjcts = new ArrayList<Project>();
                WebService webService = new WebService("http://liebenwald.spendino.net/admanager/dev/android/projects.json");
                Map<String, String> params = new HashMap<String, String>();
                params.put("var", "");
                String response = webService.webGet("", params);

                try
                {
                    Type collectionType = new TypeToken<ArrayList<Project>>(){}.getType();
                    List<Project> lst= new Gson().fromJson(response, collectionType);
                    for(Project l : lst)
                    {
                        prjcts.add(l);
                        ConstantData.projectsList.add(l);
                    }
                }
                catch(Exception e)
                {
                    Log.d("Error: ", e.getMessage());
                }

                final Button project = (Button) findViewById(R.id.btn_projectslist);
                final Button infos = (Button) findViewById(R.id.btn_infos);
                final Button contact = (Button) findViewById(R.id.btn_contact);
                project.setOnClickListener(project_listener);
                infos.setOnClickListener(infos_listener);
                contact.setOnClickListener(contact_listener);

                ImageView image1;
                ImageView image2;
                ImageView image3;

                try {
                    image1 = (ImageView)findViewById(R.id.top1);
                    image2 = (ImageView)findViewById(R.id.top2);
                    image3 = (ImageView)findViewById(R.id.top3);
                  } catch( ClassCastException e ) {
                    Log.e(TAG, "Your layout must provide an image and a text view with ID's icon and text.", e);
                    throw e;
                  }


                  Bitmap cachedImage1 = null;
                  Bitmap cachedImage2 = null;
                  Bitmap cachedImage3 = null;

                  //randomize the index of image entry

                  int max = prjcts.size();
                  List<Integer> indices = new ArrayList<Integer>(max);
                  for(int c = 0; c < max; ++c)
                  {
                      indices.add(c);
                  }

                  int arrIndex = (int)((double)indices.size() * Math.random());
                  int randomIndex1 = indices.get(arrIndex);
                  indices.remove(arrIndex);


                  int randomIndex2 = indices.get(arrIndex);
                  indices.remove(arrIndex);


                  int randomIndex3 = indices.get(arrIndex);
                  indices.remove(arrIndex);



                  setImage(cachedImage1, image1, prjcts.get(randomIndex1));
                  setImage(cachedImage2, image2, prjcts.get(randomIndex2));
                  setImage(cachedImage3, image3, prjcts.get(randomIndex3));

                  image1.setOnClickListener(top_listener);
                  image2.setOnClickListener(top_listener);
                  image3.setOnClickListener(top_listener);
            }



            public void setImage(Bitmap cachedImage, final ImageView image, Project pro)
            {
                //Bitmap cachedImage1 = null;
                try {
                    cachedImage = imageLoader.loadImage(pro.smallImageUrl, new ImageLoadedListener() 
                    {
                        public void imageLoaded(Bitmap imageBitmap)
                        {
                            image.setImageBitmap(imageBitmap);
                            //notifyDataSetChanged();                
                        }
                    });
                } catch (MalformedURLException e) {
                    Log.e(TAG, "Bad remote image URL: " + pro.smallImageUrl, e);
                }
                if( cachedImage != null ) {
                    image.setImageBitmap(cachedImage);
                  }
            }


            private OnClickListener top_listener = new OnClickListener() {
                public void onClick(View v) {
                            Intent top = new Intent(Main.this, InfosActivity.class);
                            startActivity(top);
                }
                };

ProjectDetail.java

public class ProjectDetail extends Activity implements OnClickListener{


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.project);

        Button weitersagen = (Button) findViewById(R.id.btn_weitersagen);
        weitersagen.setOnClickListener(this);

        Button sms = (Button) findViewById(R.id.btn_sms_spenden);
        sms.setOnClickListener(this);

        int position = getIntent().getExtras().getInt("spendino.de.ProjectDetail.position");
        Project project = ConstantData.projectsList.get(position);


      try {
          ImageView projectImage = (ImageView)findViewById(R.id.project_image);
          Bitmap bitmap = BitmapFactory.decodeStream((InputStream)new URL(project.bigImageUrl).getContent());
          projectImage.setImageBitmap(bitmap); 
        } catch (MalformedURLException e) {
          e.printStackTrace();
        } catch (IOException e) {
          e.printStackTrace();
        } 

      TextView project_title = (TextView)findViewById(R.id.txt_project_title);
      project_title.setText(project.project_title);

      TextView organization_title = (TextView)findViewById(R.id.txt_organization_title);
      organization_title.setText(Html.fromHtml("von " +project开发者_JAVA百科.organization_title));

      TextView project_description = (TextView)findViewById(R.id.txt_project_description);
      project_description.setText(Html.fromHtml(project.project_description));

    }

I also have this ConstantData.java, the index which holds my JSON properties:

 public class ConstantData{

   public static String project_title = "project title";
   public static String organization_title = "organization title";
   public static String keyword = "keyword";
   public static String short_code = "short code";
   public static String project_description = "description";
   public static String smallImageUrl = "smallImageUrl";
   public static String bigImageUrl = "bigImageUrl";
   public static String price= "price";
   public static String country= "country";



    public static ArrayList<Project> projectsList = new ArrayList<Project>();


    public int describeContents() {
        return 0;
    }

    public void writeToParcel(Parcel out, int flags) {
        out.writeString(project_title);
        out.writeString(organization_title);
        out.writeString(keyword);
        out.writeString(short_code);
        out.writeString(project_description);
        out.writeString(smallImageUrl);
        out.writeString(bigImageUrl);
        out.writeString(price);
        out.writeString(country);
    }

    public static final Parcelable.Creator<ConstantData> CREATOR
            = new Parcelable.Creator<ConstantData>() {
        public ConstantData createFromParcel(Parcel in) {
            return new ConstantData(in);
        }

        public ConstantData[] newArray(int size) {
            return new ConstantData[size];
        }
    };

    private ConstantData(Parcel in) {
        project_title = in.readString();
        organization_title = in.readString();
        keyword = in.readString();
        short_code = in.readString();
        project_description = in.readString();
        smallImageUrl = in.readString();
        bigImageUrl = in.readString();
        price = in.readString();
        country = in.readString();
    }
}

You could make the class ConstantData serializable by extending from Parcelable and implementing a couple of methods (see the documentation). Then you could pass a constantData instance as an extra by doing

intent.putExtra("jsonData", constantDataInstance);

and retrieving it from the other activity (in it's onCreate() method) with

getIntent().getExtras().getParcelable("jsonData");

Otherwise you could just past as extra every field independently, but it would be a mess. This way is not only more easy to read and everything, but "well designed".

To pass information from one activity to another when you start the new one you do the following:

    Intent top = new Intent(Main.this, InfosActivity.class);
    Bundle b = new Bundle();
    b.putString("key1", "value2");
    b.putString("key2", "value2");
    b.putString("key3", "value3");
    top.putExtras(b);
    startActivity(top);

Then in the newly started activity, in the onCreate() put the following:

    Bundle b = getIntent().getExtras();
    b.get("key1");
    b.get("key2");
    b.get("key3");

This will get the values from the previous activity by using the key you provided.

For more complex objects you should extend Parcelable (probably what you'll need) and then use:

b.putParcelable("Key4", yourParcelableObject);

And in your onCreate()

b.getParcelable("Key4");

I hope this helps.

Use gson to parse the json to Java. Then you can use Wagon to move the extras around with ease.

GSON: https://github.com/google/gson

Wagon: https://github.com/beplaya/Wagon