java.lang.NullPointerException in Filtering a ListView

Question

I'm trying to do a search bar that filter a listview But I'm facing this error in this line filteredProjects.add(container.getProjects().get(i)); and I can't figure out why? Any idea what the problem might be? Thank you for helping I would apreciate it.

    Gson gson = new GsonBuilder().setDateFormat(
            "yyyy-MM-dd'T'HH:mm:ssZ").create();

    final ProjectContainer container = gson.fromJson(resultat,
            ProjectContainer.class);
    final ListView lv = (ListView) findViewById(R.id.list);

    /**
     * Updating parsed JSON data into ListView
     * */
    adaptateur = new ProjectAdapter(ProjectActivity.this,
            R.layout.ligne_project, container);

    lv.setAdapter(adaptateur);

    // setListAdapter(adaptateur);
    // Search EditText
    EditText inputSearch;
    inputSearch = (EditText) findViewById(R.id.inputSearch);
    /**
     * Enabling Search Filter
     * */
    inputSearch.addTextChangedListener(new TextWatcher() {

        @SuppressWarnings("null")
        @Override
        public void onTextChanged(CharSequence s, int arg1, int arg2,
                int arg3) {
            ProjectContainer filteredProjects = null;

            if (!s.toString().equals("")) {
                for (int i = 0; i < container.getProjects().size(); i++) {
                    if (container.getProjects().get(i)
                            .getAbbreviation().toString().contains(s)) {
                        filteredProjects.setProjects(null);
                        filteredProjects.add(container.getProjects()
                                .get(i));
                    }
                }
                adaptateur = new ProjectAdapter(ProjectActivity.this,
                        R.layout.ligne_project, filteredProjects);

                lv.setAdapter(adaptateur);
            } else {
                adaptateur = new ProjectAdapter(ProjectActivity.this,
                        R.layout.ligne_project, container);
                lv.setAdapter(adaptateur);
            }

        }

        @Override
        public void beforeTextChanged(CharSequence arg0, int arg1,
                int arg2, int arg3) {
            // TODO Auto-generated method stub

        }

        @Override
        public void afterTextChanged(Editable arg0) {
            // TODO Auto-generated method stub
        }
    });

And this is my ProjectContainer.class :

import java.util.List;

import com.google.gson.annotations.SerializedName;

    public class ProjectContainer {
        @SerializedName("project")
        List<Project> projects;

        public List<Project> getProjects() {
            return projects;
        }

        public void setProjects(List<Project> projects) {
            this.projects = projects;
        }

        public void add(Project project) {
            projects.add(project);
        }
    }

Community · Accepted Answer · 2017-05-23 12:03:26Z

1

You need to instantiate filteredProjects. Try changing

ProjectContainer filteredProjects = null;

to

ProjectContainer filteredProjects = new ProjectContainer();

You are also setting the projects list in filteredProjects to null at this line:

filteredProjects.setProjects(null);

This will cause a NullPointerException when you call filteredProjects.add(..). You need to assign a new listm instead of null.

filteredProjects.setProjects(new List<Project>());

I can recommend this answer about null values if you aren't entirely sure what it is.

edited May 23, 2017 at 12:03

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answered May 12, 2013 at 20:30

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Comments

stinepike · Accepted Answer · 2013-05-12 19:21:10Z

1

  public void add(Project project) {
        projects.add(project);
    }

In the above line you used an uninitialized instance projects.

So better call setProjects method before calling add method

answered May 12, 2013 at 19:21

stinepike

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1 Comment

Wijden Over a year ago

Thanks for your reply, but I updated my question and I called setProjects method before calling add method but I got java.lang.NullPointerException in this line filteredProjects.setProjects(null);

hd1 · Accepted Answer · 2013-05-12 19:22:19Z

1

You aren't calling setProjects in the code snippet above, just defining it. Therefore, uninitialised objects are null, per the language definition, and will throw a NullPointerException when access is attempted.

answered May 12, 2013 at 19:22

hd1

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