К сожалению, программа остановлена. FATAL ИСКЛЮЧЕНИЕ: главный, java.lang.NullPointerException

Question

У меня есть проблема, им пытаются запрограммировать акселерометр, с графиками, но когда им работает приложение я получил эти ошибки, к сожалению, программа остановилась:

Process: com.example.egnasz.myapplication, PID: 7963 
        java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.egnasz.myapplication/com.example.egnasz.myapplication.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object java.lang.ref.WeakReference.get()' on a null object reference 
         at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2534) 
         at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2614) 
         at android.app.ActivityThread.access$800(ActivityThread.java:178) 
         at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1470) 
         at android.os.Handler.dispatchMessage(Handler.java:111) 
         at android.os.Looper.loop(Looper.java:194) 
         at android.app.ActivityThread.main(ActivityThread.java:5643) 
         at java.lang.reflect.Method.invoke(Native Method) 
         at java.lang.reflect.Method.invoke(Method.java:372) 
         at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:960) 
         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 
        Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object java.lang.ref.WeakReference.get()' on a null object reference 
Disconnected from the target VM, address: 'localhost:8600', transport: 'socket' 
         at com.telerik.widget.palettes.ChartPalettes.dark(ChartPalettes.java:108) 
         at com.example.egnasz.myapplication.MainActivity.createChart(MainActivity.java:212) 
         at com.example.egnasz.myapplication.MainActivity.onCreate(MainActivity.java:111) 
         at android.app.Activity.performCreate(Activity.java:6100) 

хау Исправить это?

MainActivity:

public class MainActivity extends Activity implements SensorEventListener { 

    private static final int X_AXIS_INDEX = 0; 
    private static final int Y_AXIS_INDEX = 1; 
    private static final int Z_AXIS_INDEX = 2; 

    private int defaultCoolDown; 
    private int coolDown; 

    private int bufferSize; 
    private int currentAxisIndex = X_AXIS_INDEX; 

    private int framesCount = 0; 
    boolean stopped = true; 

    private SensorManager sensorManager; 
    private Sensor accelerometer; 

    private ViewGroup chartContainer; 

    private RadCartesianChartView chart; 

    private Queue<SeismicDataPoint> seismicActivityBuffer; 
    private List<SeismicDataPoint> allSeismicActivity; 

    @Override 
    public void onSensorChanged(SensorEvent event) { 
     if (this.stopped || this.coolDown-- > 0) { 
      return; 
     } 

     this.coolDown = this.defaultCoolDown; 
     if (this.seismicActivityBuffer.size() > this.bufferSize) { 
      this.seismicActivityBuffer.remove(); 
     } 

     SeismicDataPoint point = new SeismicDataPoint(this.framesCount++, event.values[this.currentAxisIndex]); 

     this.seismicActivityBuffer.add(point); 
     this.allSeismicActivity.add(point); 

     this.chartContainer.removeAllViews(); 
     this.chart = createChart(seismicActivityBuffer); 
     this.chartContainer.addView(chart); 
    } 

    @Override 
    public void onAccuracyChanged(Sensor sensor, int accuracy) { 
    } 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 

     // hide the actionBar 
     getWindow().requestFeature(Window.FEATURE_ACTION_BAR); 
     getActionBar().hide(); 

     // To be tweaked for performance on different devices 
     Resources resources = getResources(); 
     this.defaultCoolDown = Integer.parseInt(resources.getString(R.string.default_cool_down)); 
     this.bufferSize = Integer.parseInt(resources.getString(R.string.buffer_size)); 

     this.coolDown = this.defaultCoolDown; 

     setContentView(R.layout.activity_main); 

     this.sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE); 
     this.accelerometer = this.sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER); 

     this.seismicActivityBuffer = new LinkedList<SeismicDataPoint>(); 
     this.allSeismicActivity = new ArrayList<SeismicDataPoint>(); 

     // Adding points to fill the screen at initial state. 
     for (int i = -this.bufferSize; i < 0; i++) { 
      this.seismicActivityBuffer.add(new SeismicDataPoint(i, 0)); 
     } 

     this.chartContainer = (ViewGroup) findViewById(R.id.chart_container); 

     this.chart = createChart(this.seismicActivityBuffer); 
     this.chartContainer.addView(this.chart); 

     Button startBtn = (Button) findViewById(R.id.start_btn); 
     startBtn.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       stop(); 
       stopped = false; 
      } 
     }); 

     Button stopBtn = (Button) findViewById(R.id.stop_btn); 
     stopBtn.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       stop(); 
      } 
     }); 

     Button resetBtn = (Button) findViewById(R.id.reset_btn); 
     resetBtn.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       Intent intent = getIntent(); 
       finish(); 
       startActivity(intent); 
      } 
     }); 

     // The activity is forced to landscape, so X and Y are different in phone and tablet devices. 
     final RadioGroup axisSelectionMenu = (RadioGroup) findViewById(R.id.axis_selection); 
     axisSelectionMenu.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() { 
      @Override 
      public void onCheckedChanged(RadioGroup group, int checkedId) { 
       switch (checkedId) { 
        case R.id.axis_x: 
         currentAxisIndex = X_AXIS_INDEX; 
         break; 
        case R.id.axis_y: 
         currentAxisIndex = Y_AXIS_INDEX; 
         break; 
        case R.id.axis_z: 
         currentAxisIndex = Z_AXIS_INDEX; 
         break; 
        default: 
         throw new IllegalArgumentException("there are only 3 axes"); 
       } 
      } 
     }); 
    } 

    @Override 
    protected void onResume() { 
     super.onResume(); 
     this.sensorManager.registerListener(this, this.accelerometer, SensorManager.SENSOR_DELAY_FASTEST); 
    } 

    @Override 
    protected void onPause() { 
     super.onPause(); 
     this.sensorManager.unregisterListener(this); 
    } 

    private RadCartesianChartView createChart(Iterable<SeismicDataPoint> dataPoints) { 
     RadCartesianChartView chart = new RadCartesianChartView(this); 
     LinearAxis vAxis = new LinearAxis(); 

     // The maximum value of the accelerometer is 20 and the minimum -20, so give a bonus 10 to the vertical axis. 
     vAxis.setMaximum(30); 
     vAxis.setMinimum(-30); 

     CategoricalAxis hAxis = new CategoricalAxis(); 
     hAxis.setShowLabels(false); 

     DataPointBinding categoryBinding = new DataPointBinding() { 
      @Override 
      public Object getValue(Object o) throws IllegalArgumentException { 
       return ((SeismicDataPoint) o).x; 
      } 
     }; 

     DataPointBinding valueBinding = new DataPointBinding() { 
      @Override 
      public Object getValue(Object o) throws IllegalArgumentException { 
       return ((SeismicDataPoint) o).y; 
      } 
     }; 

     LineSeries series = new LineSeries(); 
     series.setCategoryBinding(categoryBinding); 
     series.setValueBinding(valueBinding); 
     series.setData(dataPoints); 

     CartesianChartGrid grid = new CartesianChartGrid(); 

     chart.setGrid(grid); 
     chart.setVerticalAxis(vAxis); 

     chart.setHorizontalAxis(hAxis); 
     chart.getSeries().add(series); 
     chart.setPalette(ChartPalettes.dark()); 
     chart.setEmptyContent(""); 

     // Customize chart elements after adding them to the chart to override the application of the palette. 
     hAxis.setTickColor(Color.TRANSPARENT); 
     grid.setMajorYLinesRenderMode(GridLineRenderMode.INNER_AND_LAST); 
     vAxis.setLineColor(Color.TRANSPARENT); 
     return chart; 
    } 

    private void stop() { 
     this.stopped = true; 
     this.chartContainer.removeAllViews(); 
     this.chart = createChart(this.allSeismicActivity); 
     this.chartContainer.addView(this.chart); 
    } 
} 

SeismicDataPoint:

public class SeismicDataPoint { 

    public int x; 
    public float y; 

    public SeismicDataPoint(int x, float y) { 
     this.x = x; 
     this.y = y; 
    } 
} 

activity_main.xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:tools="http://schemas.android.com/tools" 
    android:id="@+id/activity_main" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:paddingBottom="@dimen/activity_vertical_margin" 
    android:paddingLeft="@dimen/activity_horizontal_margin" 
    android:paddingRight="@dimen/activity_horizontal_margin" 
    android:paddingTop="@dimen/activity_vertical_margin" 
    tools:context="com.example.egnasz.myapplication.MainActivity"> 

    <LinearLayout 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:orientation="vertical" 
     android:id="@+id/side_menu"> 

     <Button 
      android:layout_width="75dp" 
      android:layout_height="wrap_content" 
      android:text="Start" 
      android:id="@+id/start_btn" /> 

     <Button 
      android:layout_width="75dp" 
      android:layout_height="wrap_content" 
      android:text="Stop" 
      android:id="@+id/stop_btn" 
      android:layout_marginTop="5dp" 
      android:layout_marginBottom="5dp" /> 

     <Button 
      android:layout_width="75dp" 
      android:layout_height="wrap_content" 
      android:text="Reset" 
      android:id="@+id/reset_btn" /> 

     <RadioGroup 
      android:id="@+id/axis_selection" 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content" 
      android:layout_marginTop="10dp"> 

      <RadioButton 
       android:id="@+id/axis_x" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:text="X-axis" 
       android:checked="true" /> 

      <RadioButton 
       android:id="@+id/axis_y" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:text="Y-axis" 
       android:layout_marginTop="5dp" 
       android:layout_marginBottom="5dp" /> 

      <RadioButton 
       android:id="@+id/axis_z" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:text="Z-axis" /> 
     </RadioGroup> 

    </LinearLayout> 

    <FrameLayout 
     android:paddingRight="20dp" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:id="@+id/chart_container" 
     android:layout_toRightOf="@id/side_menu" 
     android:layout_marginBottom="10dp" 
     android:layout_marginTop="5dp" /> 

</RelativeLayout> 

манифеста:

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="com.example.egnasz.myapplication"> 
    <application 
     android:allowBackup="true" 
     android:icon="@mipmap/ic_launcher" 
     android:label="@string/app_name" 
     android:supportsRtl="true" 
     android:theme="@style/AppTheme"> 
     <activity android:name=".MainActivity"> 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 

       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 
    </application> 

</manifest> 

build.gradle:

repositories { 
    mavenCentral() 
    flatDir { 
     dirs 'libs' 
    } 
} 

android { 
    compileSdkVersion 24 
    buildToolsVersion "25.0.0" 
    defaultConfig { 
     applicationId "com.example.egnasz.myapplication" 
     minSdkVersion 16 
     targetSdkVersion 24 
     versionCode 1 
     versionName "1.0" 
     testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner" 
    } 
    buildTypes { 
     release { 
      minifyEnabled false 
      proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' 
     } 
    } 
} 

dependencies { 
    compile fileTree(dir: 'libs', include: ['*.jar']) 
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', { 
     exclude group: 'com.android.support', module: 'support-annotations' 
    }) 
    compile 'com.android.support:appcompat-v7:24.2.1' 
    compile (name: 'Chart-2016.3.914-trial-release', ext: 'aar') 
    compile (name: 'Common-2016.3.914-trial-release', ext: 'aar') 
    compile (name: 'Primitives-2016.3.914-trial-release', ext: 'aar') 
    testCompile 'junit:junit:4.12' 
} 

Answer 1

Если вы не хотите ActionBar в вашем Activity, вы можете удалить следующие строки из кода:

// hide the actionBar 
getWindow().requestFeature(Window.FEATURE_ACTION_BAR); 
getActionBar().hide(); 

И заменить родитель вашего AppTheme с:

Theme.AppCompat.Light.NoActionBar 

Answer 2

Просто замените AppTheme родителя на Theme.AppCompat.Light.NoActionBar (и удалять строки фр ом getWindow() к .hide();, или использовать следующий метод getSupportActionBar().hide();, потому что, так как вы используете AppCompat, v4.Toolbar заменяется v7.Toolbar, а также getActionBar() возвращается v4.Toolbar, вы не можете использовать его.

Answer 3

Продлить вам activity as AppCompatActivity, а затем использовать панель действий, как: -

getSupportActionBar().hide(); // for hiding 
getSupportActionBar().show(); // for showing 

надеюсь, что это помогает