Question

我正在使用LightSensor和Checkbox来启用或禁用用户的LightSensor。使用SharedPreferences来存储和检索CheckBox状态，但无法使其按照我想要的方式工作：

如果用户点击LightSensor复选框并启动操作并退出应用程序，当他返回该应用程序时，LightSensor复选框应该在UI上“勾选” - 即使我'也不会发生这种情况使用了onResume（）方法并实现了我的代码，如下所示：
如果用户单击LightSensor复选框并启动操作并退出应用程序，当他返回该应用程序时，在这种情况下，在UI上取消选中LightSensor Checkbox。这很好。

onPause（），onResume（）下面的代码片段。没有错误，但它没有像我上面解释的那样工作。：

最新代码如下所示

@Override
        public void onPause() {
            super.onPause();
            SharedPreferences.Editor editor = mSharedPreferences.edit();
            editor.putBoolean("LightSensorValue", isLightSensorON);
            editor.commit();
            // on pause turn off the flash
            turnOffFlash();
           // tggle_Text_Button.setChecked(false);
            mSensorManager.unregisterListener(this);
        }


        @Override
        public void onResume() {
            super.onResume();

            // on resume turn on the flash
            if (hasFlash) {

                // turnONFlash();
                tggle_Text_Button.setChecked(false);
                // Setting the Default Value for the CheckBox to 'False' during
                // resume and retrieving the actual value
                // from the SharedPreferences
                if (mSharedPreferences.getBoolean("LightSensorValue", false)) {
                    ChkBox_LightSensor.setChecked(true); // to Tick The CheckBox
                                                            // on the UI if the
                                                            // SharedPreferences
                    // returns 'True' value
                    isLightSensorON = true;
                    turnONLightSensor();
                } else {
                    ChkBox_LightSensor.setChecked(false);
                    isLightSensorON = false;
                    turnOFFLightSensor();
                }
            }

        }

        @Override
        public void onStart() {
            super.onStart();

            // on starting the app get the camera params
            getCamera();
        }

        @Override
        public void onStop() {
            super.onStop();

            // on stop release the camera
            if (camera != null) {
                camera.release();
                camera = null;
            }
        }

        @Override
        public void onAccuracyChanged(Sensor sensor, int accuracy) {
            // TODO Auto-generated method stub

        }

        /*
         * 
         * When light sensor detects, it's value below <2, the flash light
         * automatically gets ON and in case if the light sensor detects, it's
         * values above 2...the flash light automatically gets OFF
         */
        @Override
        public void onSensorChanged(SensorEvent event) {
            // TODO Auto-generated method stub

            float lux = event.values[0];
            int luxInt = (int) lux;
            // tV_light_Value.setText(String.valueOf(lux));
            Log.d("BRK0018 - LightSensor", "New Light value occurred : " + lux
                    + "   :   " + luxInt);
            if (event.values[0] <= 2.0) {
                turnONFlash();
                Log.d("BRK0018 - LightSensor",
                        "New Light value LOW occurred : " + luxInt);
                Log.d("BRK0018 - LightSensor",
                        "LightSensor switched on the Flash");
            } else {
                turnOffFlash();
                Log.d("BRK0018 - LightSensor", "New Light value is HIGH : "
                        + luxInt);
                Log.d("BRK0018 - LightSensor",
                        "LightSensor switched OFF the Flash");
            }

        }

        // When Light Sensor Checkbox is checked, below is the initialization of
        // the LightSensor and the
        // SensorManager

        @Override
        public void onClick(View view) {
            // TODO Auto-generated method stub
            boolean isLightSensorON = ChkBox_LightSensor.isChecked();
            if (isLightSensorON) {
                turnONLightSensor();
            } else {
                turnOFFLightSensor();
            }

        }

        private void turnONLightSensor() {
            // TODO Auto-generated method stub
            SharedPreferences.Editor editor = mSharedPreferences.edit();
            editor.putBoolean("LightSensorValue", isLightSensorON);
            editor.commit();
            isLightSensorON = true;
            mSensorManager = (SensorManager) getActivity().getSystemService(
                    Context.SENSOR_SERVICE);
            if (mSensorManager.getSensorList(Sensor.TYPE_LIGHT).size() != 0) {
                Sensor mLightSensor = mSensorManager.getSensorList(
                        Sensor.TYPE_LIGHT).get(0);
                mSensorManager.registerListener(this, mLightSensor,
                        SensorManager.SENSOR_DELAY_NORMAL);
                Toast.makeText(getActivity(), "LightSensor is ACTIVE now", 1000)
                        .show();
            }
        }

        private void turnOFFLightSensor() {
            // TODO Auto-generated method stub
            isLightSensorON = false;
            SharedPreferences.Editor editor = mSharedPreferences.edit();
            editor.putBoolean("LightSensorValue", isLightSensorON);
            editor.commit();

            Toast.makeText(getActivity(), "Light Sensor is INACTIVE now", 1000)
                    .show();
        }

    }

Answer 1

从您的代码中我不知道您是否曾从用户输入中设置isLightSensorON = true;。同样，每个onPause您都会将偏好设置为偏好设置，因此在每个onResume您都会将其设置为假。

Answer 2

**我最新更新的答案。**

分享细节，以便对像我这样的其他新手有所帮助。

我已尝试mSensorManager.unregisterListener(this);将else置于onResume()以及'turnOFFLightSensor()'，但在这两种情况下，该应用都崩溃而没有任何错误注释。

然后，再次查看代码，发现了错误:(

在onClick()的{{1}}中，我已将LightSensor Checkbox放置在onPause（）之外。这解决了这个问题。

** Bottomline，简单来说**当我取消选中该框时，立即取消注册LightSensor。这让我的一天！：）

mSensorManager.unregisterListener(this);

BTW， 非常感谢@Eugen Martynov 一直帮助我！

无法根据存储在＆amp;中的值在UI上勾选复选框取自SharedPreferences

2 个答案: