Android:将一个活动的额外活动传递给另一个活动

Question

我有一个JSON文件,填充到一个活动(Main.java).

此活动显示来自我的JSON条目上的URL的3个随机图像.

我想做的是:我在我的JSON上有13个不同的条目,每当我点击显示的随机图片时,它转到另一个包含图片,标题和描述的活动(ProjectDetail.java)取决于我点击的项目进入JSON.

我有什么是通过使用额外的我不知道如何执行,因为我使用JSON.我应该top_listener在我的Main类的方法中添加什么以及我应该在ProjectDetail类中添加什么？

谢谢.

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.organization_title));

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

    }

我也有这个ConstantData.java,它是保存我的JSON属性的索引:

 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();
    }
}

Answer 1

您可以通过从Parcelable扩展并实现几种方法使类ConstantData可序列化(请参阅文档).然后你可以通过做一个额外的传递一个constantData实例

intent.putExtra("jsonData", constantDataInstance);

用其他活动(在它的onCreate()方法中)检索它

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

否则你可以独立地超越每个领域,但这将是一个烂摊子.这种方式不仅更容易阅读和一切,但"精心设计".