如何在android

Question

我不确定在从解析中检索数据时如何添加进度条或创建加载对话框。 这是我的代码，用于从解析中检索数据。我尝试了很少的教程，但似乎没有一个对我有用。

public class HolidayActivity extends AppCompatActivity {

    private HolidayAdapter mAdapter;

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

        //noinspection ConstantConditions
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setIcon(R.drawable.dl);
        ParseObject.registerSubclass(Holiday.class);

        mAdapter = new HolidayAdapter(this, new ArrayList<Holiday>());

        ListView mListView = (ListView) findViewById(R.id.holiday_list);
        mListView.setAdapter(mAdapter);

        updateData();
    }

    public void updateData() {
        ParseQuery<Holiday> query = ParseQuery.getQuery(Holiday.class);

        query.setCachePolicy(ParseQuery.CachePolicy.CACHE_THEN_NETWORK);
        query.findInBackground(new FindCallback<Holiday>() {
            @Override
            public void done(List<Holiday> holidays, com.parse.ParseException e) {

                if (holidays != null) {
                    mAdapter.clear();
                    for (int i = 0; i < holidays.size(); i++) {
                        mAdapter.add(holidays.get(i));
                    }
                }
            }
        });
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case android.R.id.home:
                // app icon in action bar clicked; goto parent activity.
                this.finish();
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }
}

Answer 1

将此添加到您的updateData()：

public void updateData() {
    final ProgressDialog progressDialog = ProgressDialog.show(this, null, "Loading…");

    (…)

        @Override
        public void done(List<Holiday> holidays, com.parse.ParseException e) {
            progressDialog.dismiss();

            (…)
        }
}

希望它有所帮助！