Android，如何动态更新 ListView 项和所有后续项？

Question

I have a ListView that displays an ArrayList that is dynamically created using an adapter. However, certain elements of each list item view are calculated based on previous item values. I am using Intents to open another activity where the user can edit a selected list item, and the updates are passed back to the main activity. In the main activity I've placed the getIntent, and the associated setters, after the ArrayList is generated and before the adapter. When the main activity is first created the adapter correctly calculates all list view items. But when the user accepts updates in the edit activity and returns to the main activity, only the selected list item is updated. Having the entire list cycle through and update would be fine (it will never be a very long list), but I'm a little surprised that only the selected list item is getting updated. I expected that either the adapter would run as it does when the activity is first created and all items would get updated, or that it wouldn't run at all and none would get updated.

public class MainActivity extends AppCompatActivity {

    private final Context thisContext = MainActivity.this;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ListView planListView = findViewById(R.id.plan_listview);

        final ArrayList<ItemProfile> planSteps = BuildPlan();

        if(getIntent().getExtras() != null)
        {
            int stepNumber = getIntent().getIntExtra("stepNumber", 0);
            ItemProfile thisStep = (ItemProfile) getIntent().getSerializableExtra("itemProfile");

            planSteps.get(stepNumber-1).setDepth(thisStep.getDepth());
            planSteps.get(stepNumber-1).setTime(thisStep.getTime());
            planSteps.get(stepNumber-1).setInterval(thisStep.getInterval());
        }

        ItemsListAdapter planAdapter = new ItemsListAdapter(this, planSteps);
        planListView.setAdapter(planAdapter);

        planListView.setOnItemClickListener(
            new AdapterView.OnItemClickListener()
            {
                @Override
                public void onItemClick(AdapterView<?> adapterView, View view, int pos, long l)
                {
                    int index = pos-1;
                    Intent i = new Intent(thisContext, EditItemActivity.class);

                    i.putExtra("stepNumber", pos);
                    i.putExtra("stepProfile", planSteps.get(index));

                    if (index > 0)
                    {
                        i.putExtra("groupStart", planSteps.get(index-1).getGroupEnd());
                    }

                    startActivity(i);
                }
            }
        );
    }
}

Update... I've added the mainActivity code. It creates an ArrayList plan (I'm using a BuildPlan method to populate a dummy plan while I'm developing) then checks for an intent that is returning an updated plan step. If an intent exists the specified step is updated in the plan. The list adapter is then created and set. Finally the clickListener is created and set.

Answer 1

I've done something relatively similar but I used dynamic spinners and listviews from a database.

Here is the code. Basically you invalidate the list view, reset the data and call notifyDataSetChanged() on the adapter.

public  ListView lv;
Spinner suburbSpinner;
ArrayAdapter<String> suburbAdapter;
ArrayList<String> suburbs = new ArrayList<>();
ArrayList<Resource> resources = new ArrayList<>();
ArrayAdapter<Resource> arrayAdapter;

public void updateList(String type, String suburb, String businessType, int suburbPos) {
    DatabaseHelper db = new DatabaseHelper(this, "fairCanberraDB", null, 1);
    lv = findViewById(R.id.list);

    // Reset suburb spinner, get new list view resources.

    lv.invalidateViews();
    resources = db.resourceQuery(type, suburb, businessType);
    System.out.println("resource: " + resources);
    ArrayList<Resource> suburbQuery = db.resourceQuery(type, "All", businessType);
    Spinner suburbSpinner = findViewById(R.id.suburbSpinner);
    suburbs.clear();
    suburbs.add("All");

    for (int x = 0; x < suburbQuery.size(); x++) {
        if (suburbs.contains(suburbQuery.get(x).getSuburb())) {
            continue;
        } else {
            suburbs.add(suburbQuery.get(x).getSuburb());
        }
    }
    db.close();
    suburbAdapter.notifyDataSetChanged();
   arrayAdapter.notifyDataSetChanged();
    ArrayAdapter<Resource> arrayAdapter = new ArrayAdapter<Resource>(
            this,
            android.R.layout.simple_list_item_1,
            resources);

    lv.setAdapter(arrayAdapter);

    if(suburbPos < suburbSpinner.getCount())
    { suburbSpinner.setSelection(suburbPos);}
    setSpinnerListener(suburbSpinner);


}

// Register listener for a spinner
public void setSpinnerListener(Spinner spinner)
{
    spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) {
            Spinner typeSpinner = (Spinner) findViewById(R.id.typeSpinner);
            Spinner businessTypeSpinner = (Spinner) findViewById(R.id.businessTypeSpinner);
            Spinner suburbSpinner = (Spinner) findViewById(R.id.suburbSpinner);
            String businessType = businessTypeSpinner.getSelectedItem().toString();
            if(businessType.contains("Private"))
            {
                businessType = "private user";
            }

            updateList(typeSpinner.getSelectedItem().toString(), suburbSpinner.getSelectedItem().toString(),
                    businessType, suburbSpinner.getSelectedItemPosition());


        }