Question

我正在尝试调试我的应用程序，它似乎是为MainActivity运行onCreate方法两次。

我输入了Log.i（）命令，果然，它在Logcat中出现两次。

这可能是什么原因？

这是我的onCreate代码：

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    Log.i(TAG, "Starting..."); // this appear twice in logcat

    // Set activity view
    setContentView(R.layout.activity_main);

    // Initialise buttons
    Button loginBtn = (Button) findViewById(R.id.login);

    // Initialise text inputs
    screen = (EditText)findViewById(R.id.screen);
    pw = (EditText)findViewById(R.id.pw);

    final SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
    String storedScreenCode = sharedPreferences.getString("storedScreenCode", null);
    String storedScreenPassword = sharedPreferences.getString("storedScreenPassword", null);

    domain = sharedPreferences.getString("apiUrl", null);

    final String lastUpdated = sharedPreferences.getString("lastUpdated", null);

    if(storedScreenCode != null) {
        String url = domain + getResources().getString(R.string.api_login_url) + storedScreenCode + "/" + storedScreenPassword;

        try {
            status = new NetworkChecker(getApplicationContext()).execute().get(4, TimeUnit.SECONDS);
            Log.i(TAG, status.toString());
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        } catch (TimeoutException e) {
            Toast.makeText(getBaseContext(), e.getMessage(), Toast.LENGTH_LONG).show();
        }

        if(status) {
            try {
                String loginResult = new ReadJSONFeedTask().execute(url).get(4, TimeUnit.SECONDS);
                JSONObject loginJson = new JSONObject(loginResult);

                if(loginJson.getInt("success") == 1) {

                        Intent i = new Intent(getApplicationContext(), NextActivity.class);
                        startActivity(i);

                } else {

                }

            } catch (InterruptedException e) {
                e.printStackTrace();
            } catch (ExecutionException e) {
                e.printStackTrace();
            } catch (JSONException e) {
                e.printStackTrace();
            } catch (ParseException e) {
                e.printStackTrace();
            } catch (TimeoutException e) {
                e.printStackTrace();
            }
        }
    }

    loginBtn.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View view) {

            if (isEmpty(screen) && isEmpty(pw)) {
                screen.setError("Screen Code is required!");
                pw.setError("Password is required!");
            } else {
                WifiManager wifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);

                ConnectivityManager connManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
                NetworkInfo mWifi = connManager.getNetworkInfo(ConnectivityManager.TYPE_WIFI);

                if(!wifi.isWifiEnabled()) {
                    Toast.makeText(getBaseContext(), "Wifi is not enabled.", Toast.LENGTH_LONG).show();
                    startActivity(new Intent(Settings.ACTION_WIFI_SETTINGS));
                } else if(!mWifi.isConnected()) {
                    Toast.makeText(getBaseContext(), "Wifi is not connected.", Toast.LENGTH_LONG).show();
                    startActivity(new Intent(Settings.ACTION_WIFI_SETTINGS));
                } else {

                    //String domain = sharedPreferences.getString("apiUrl", null);

                    String url = domain + getResources().getString(R.string.api_login_url) + screen.getText().toString() + "/" + pw.getText().toString();
                    Log.i(TAG, "API Login URL: " + url);

                    try {
                        status = new NetworkChecker(getApplicationContext()).execute().get();
                        Log.i(TAG, "Status: " + status);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    } catch (ExecutionException e) {
                        e.printStackTrace();
                    }

                    if(status) {
                        try {
                            String loginResult = new ReadJSONFeedTask().execute(url).get();
                            JSONObject loginJson = new JSONObject(loginResult);

                            // check success boolean
                            if(loginJson.getInt("success") == 1) { // if success equals 1, carry on with activity

                                    Intent i = new Intent(getApplicationContext(), NextActivity.class);
                                    startActivity(i);
                            } else {
                                // if success equals 0, show toast
                                Toast.makeText(getBaseContext(), loginJson.getString("message") , Toast.LENGTH_LONG).show();
                            }
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        } catch (ExecutionException e) {
                            e.printStackTrace();
                        } catch (JSONException e) {
                            e.printStackTrace();
                        } catch (ParseException e) {
                            e.printStackTrace();
                        }
                    } else {
                        Toast.makeText(getBaseContext(), "No Connectivity", Toast.LENGTH_LONG).show();
                    }
                }
            }
        }
    });
  }

我把它拆分了一下，将其主要部分放入onStart（）。然后我在onCreate和onStart中放入一条日志消息，打开断点并作为调试运行。 Android Studio选择断点，首先是onCreate中的日志消息，然后是onStart中的日志消息，然后它返回onCreate并再次返回onStart。

所以有些事情肯定是在创造两次（或整个活动？）

Answer 1

如果您应该使用this或YourActivity.this，请多次使用getApplicationContext（）和getBaseContext（）。在某些情况下，这可能会导致内存泄漏。这应该是一个评论，但我没有足够的代表。很抱歉...

Answer 2

当您在活动中改变方向时通常会发生这种情况，例如：

setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

而不是清单中设置的方向：

<activity android:name=".YourActivity" android:screenOrientation="landscape"/>

祝你好运！

MainActivity onCreate运行两次

2 个答案: