Question

正在构建我的第一个Android应用程序，我有一个简单的按钮，应该获取用户的位置（并将其保存在数据库中）。单击此按钮时，我要加载的页面会加载，但在将信息保存到数据库后，它会很快消失。我确信这很简单，但对于我的生活，我无法保持新的活动。基本问题是如何在从下面的第一段代码点击按钮后，使用ACTIVE将textview保留在屏幕上。

以下是java类中用于启动活动的按钮：

public class WalkerMain extends ActionBarActivity implements View.OnClickListener{
    private Button mActive;
    public String user = null;
    public Integer user_id = 0;
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.walker_app);
        Bundle extras = getIntent().getExtras();

        if (extras != null) {
            user = extras.getString("user");
            user_id = extras.getInt("user_id");
            Log.d("In WalkerMain!", user);
        }
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        if (toolbar != null) {
            setSupportActionBar(toolbar);
        }
        mActive = (Button) findViewById(R.id.go_active);
        // register listeners
        mActive.setOnClickListener(this);
    }
    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
                Intent i = new Intent(this, WalkerActive.class);
                i.putExtra("user", user);
                i.putExtra("user_id", user_id);
                startActivity(i);

        }
    }

更新用户信息的活动，应该只在内容视图上显示一个简单的文本框。

public class WalkerActive extends ActionBarActivity implements
        GoogleApiClient.ConnectionCallbacks,
        GoogleApiClient.OnConnectionFailedListener,
        LocationListener
{

    private ProgressDialog pDialog;

    //ids
    private static final String TAG_SUCCESS = "success";
    private static final String TAG_MESSAGE = "message";
    public Double lat, lon;
    public Integer radius = 0;
    public String user = null;
    public Integer user_id = null;
    public JSONParser jsonParser = new JSONParser();

    private static final String UPDATE_URL = "...";
    private final String TAG = "APP";

    private TextView mLocationView;

    private GoogleApiClient mGoogleApiClient;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.walker_active);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        if (toolbar != null) {
            setSupportActionBar(toolbar);
        }

        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addApi(LocationServices.API)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .build();
    }

    @Override
    protected void onStart() {
        super.onStart();
        // Connect the client.
        mGoogleApiClient.connect();
    }

    @Override
    protected void onStop() {
        // Disconnecting the client invalidates it.
        mGoogleApiClient.disconnect();
        super.onStop();
    }

    @Override
    public void onConnected(Bundle bundle) {
        // Display the connection status
        LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        List<String> providers = lm.getProviders(true);

        /* Loop over the array backwards, and if you get an accurate location, then break out the loop*/
        Location l = null;

        for (int i=providers.size()-1; i>=0; i--) {
            l = lm.getLastKnownLocation(providers.get(i));
            if (l != null) break;
        }

        if (l != null) {
            lat = l.getLatitude();
            lon = l.getLongitude();
        }
        Bundle extras = getIntent().getExtras();
        if (extras != null) {
            user = extras.getString("user");
            user_id = extras.getInt("user_id");
            Log.d("In WalkerActive", user);
        }
        String ret_value = null;
        try {
            ret_value = new UpdateActive().execute().get();
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    @Override
    public void onConnectionSuspended(int i) {
        Log.i(TAG, "GoogleApiClient connection has been suspend");
    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        Log.i(TAG, "GoogleApiClient connection has failed");
    }

    @Override
    public void onLocationChanged(Location location) {
        mLocationView.setText("Location received: " + location.toString());
    }



    class UpdateActive extends AsyncTask<String, String, String> {


        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(WalkerActive.this);
            pDialog.setMessage("Going Active...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(true);
            pDialog.show();
        }

        @Override
        protected String doInBackground(String... args) {
            // TODO Auto-generated method stub
            // Check for success tag
            int success;
            try {
                // Building Parameters
                List<NameValuePair> params = new ArrayList<NameValuePair>();
                params.add(new BasicNameValuePair("user_id", user_id.toString()));
                params.add(new BasicNameValuePair("radius", radius.toString()));
                params.add(new BasicNameValuePair("lat", lat.toString()));
                params.add(new BasicNameValuePair("lon",lon.toString()));
                Log.d("request!", "starting");
                Log.d("params",params.toString());
                JSONObject json_update = jsonParser.makeHttpRequest(
                        UPDATE_URL, "POST", params);
                //Log.d("completed",json.toString());
                // full json_update response
                Log.d("Updated Activity", json_update.toString());

                // json_update success element
                success = json_update.getInt(TAG_SUCCESS);
                if (success == 1) {
                    Log.d("Updated Activity!", json_update.toString());
                    finish();
                    return json_update.getString(TAG_MESSAGE);
                }else{
                    Log.d("Registering Failure!", json_update.getString(TAG_MESSAGE));
                    return json_update.getString(TAG_MESSAGE);

                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

            return null;

        }

        protected void onPostExecute(String file_url) {
            // dismiss the dialog once product deleted
            pDialog.dismiss();

        }

    }
}

walker_active.xml非常简单

<?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    <android.support.v7.widget.Toolbar
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?attr/colorPrimaryDark"/>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="ACTIVE"
        android:id="@+id/textView"
        android:layout_gravity="center_horizontal"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true" />

</RelativeLayout>

Answer 1

看完你的代码之后 oka

if (success == 1) {
                    Log.d("Updated Activity!", json_update.toString());
                    finish();
                    return json_update.getString(TAG_MESSAGE);
                }

在这个if语句中finish();执行的是此代码在后台运行，因此Finish（）;语句只是停止当前正在运行的函数并停止视图。尝试删除Finish（）;声明

内容很快消失

1 个答案: