使用Volley库

Question

我知道这个话题已经存在一些问题 我访问了每个链接，但没有帮助。

我要做的是从MySQL获取值并平行更新UI而不使用AsyncTask。
我正在根据我从另一个Activity获取的唯一ID获取值。

我认为因为我使用的是Volley库，所以我不需要AsyncTask 我在吐司中从数据库中获取值，但我无法更新UI。

这是我的班级

public class DisplayInformationActivity extends Activity implements AppCompatCallback{
    private CollapsingToolbarLayout collapsingToolbarLayout;
    protected AppCompatDelegate delegate;
    protected String UniqueID;
    ExpandableListAdapter listAdapter;
    ExpandableListView expListView;
    List<String> listDataHeader;
    HashMap<String,List<String>> listDataChild;
    private ProgressDialog loading;
    private String Name = "";
    private String contact = "";
    private String email = "";

    protected void onCreate(Bundle savedInstanceState){
        UniqueID = getIntent().getStringExtra("uniqueID");
        Toast.makeText(this,UniqueID, Toast.LENGTH_LONG).show();
        fetchEverything(UniqueID);
        super.onCreate(savedInstanceState);
        delegate = AppCompatDelegate.create(this,this);
        delegate.onCreate(savedInstanceState);
        delegate.setContentView(R.layout.displayhallinformation);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        delegate.setSupportActionBar(toolbar);
        android.app.ActionBar actionBar = getActionBar();
        if(actionBar!=null)
            actionBar.setDisplayHomeAsUpEnabled(true);
        collapsingToolbarLayout = (CollapsingToolbarLayout) findViewById(R.id.collapsing_toolbar);
        collapsingToolbarLayout.setTitle(Name);
        dynamicToolbarColor();
        toolBarTextAppearance();
        expListView = (ExpandableListView) findViewById(R.id.expandableListView);
        prepareListData();
        listAdapter = new ExpandableListAdapter(this,listDataHeader,listDataChild);
        expListView.setAdapter(listAdapter);
    }

    private void fetchEverything(String uniqueID) {
        RequestQueue mRequestQueue = AppController.getInstance().getRequestQueue();
        mRequestQueue.start();
        loading = ProgressDialog.show(this,"Loading Information ...","",false,false);
        loading.setCancelable(false);
        String url = AppConfig.URL_DisplayInformation+"?"+"uniqueID="+uniqueID;
        StringRequest stringRequest = new StringRequest(Request.Method.GET, url, new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {
                loading.dismiss();
                showJSON(response);
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Toast.makeText(getApplicationContext(), error.getMessage(), Toast.LENGTH_SHORT).show();
            }
        });
        AppController.getInstance().addToRequestQueue(stringRequest);
    }

    private void showJSON(String response) {
        try{
            JSONObject jsonObject = new JSONObject(response);
            JSONArray result = jsonObject.getJSONArray(AppConfig.JSON_ARRAY);
            JSONObject Data = result.getJSONObject(0);
            Name = Data.getString(AppConfig.first_name)+" "+Data.getString(AppConfig.last_name);
            contact = Data.getString(AppConfig.contact);
            email = Data.getString(AppConfig.email);
        }catch (JSONException e){
            e.printStackTrace();
        }
        Toast.makeText(this, Name+" "+contact+" "+email, Toast.LENGTH_LONG).show();
    }

    private void prepareListData() {
        listDataHeader = new ArrayList<>();
        listDataChild = new HashMap<String,List<String>>();

        //Adding header to expandable list view
        listDataHeader.add("Information");
        listDataHeader.add("Contact");
        //Adding child data
        List<String> Information = new ArrayList<>();
        Information.add("Name : "+Name);
        List<String> contact = new ArrayList<>();
        contact.add("Contact Number : "+ contact);
        contact.add("Email : "+ email);

        //Header child data
        listDataChild.put(listDataHeader.get(0),Information);
        listDataChild.put(listDataHeader.get(1),contact);
    }

    private void dynamicToolbarColor() {
        Bitmap bitmap = BitmapFactory.decodeResource(getResources(),
                R.drawable.images);
        Palette.from(bitmap).generate(new Palette.PaletteAsyncListener() {
            @Override
            public void onGenerated(Palette palette) {
                collapsingToolbarLayout.setContentScrimColor(palette.getMutedColor(ContextCompat.getColor(getApplicationContext(),R.color.colorPrimary)));
                collapsingToolbarLayout.setStatusBarScrimColor(palette.getMutedColor(ContextCompat.getColor(getApplicationContext(),R.color.colorPrimaryDark)));
            }
        });
    }

    private void toolBarTextAppearance() {
        collapsingToolbarLayout.setCollapsedTitleTextAppearance(R.style.collapsedappbar);
        collapsingToolbarLayout.setExpandedTitleTextAppearance(R.style.expandedappbar);
    }

    @Override
    public void onSupportActionModeStarted(ActionMode mode) {

    }

    @Override
    public void onSupportActionModeFinished(ActionMode mode) {

    }

    @Nullable
    @Override
    public ActionMode onWindowStartingSupportActionMode(ActionMode.Callback callback) {
        return null;
    }
}

如何异步更新UI？

Answer 1

  

我如何平行更新ui？

您需要组织＆＃34;流程＆＃34;更好。

例如。 （缩进意思是方法调用）

onCreate
  fetchEverything
    addToRequestQueue(stringRequest)
      onResponse
        showJSON
          collapsingToolbarLayout.setTitle(Name)  // <---- Move this here
          prepareListData() // <---- Move this here
          expListView = new ExpandableListAdapter...
          expListView.setAdapter(listAdapter) // <--- Move this here
          Update UI 
          // ^^^ This section your question?

目前您的代码可能正在执行此操作

onCreate
  fetchEverything
    addToRequestQueue(stringRequest)
  collapsingToolbarLayout.setTitle(Name)
  prepareListData()
  expListView = new ExpandableListAdapter...
  expListView.setAdapter(listAdapter)
...
(some unknown future point)
  onResponse
    showJSON
      Toast.makeText

所以，换句话说，showJSON（以及你的排球数据）直到 之后才进入你的工具栏和适配器。