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POaChartEngine NullPointerExeption on XYSeries.add(x,y) method
 

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  1. POaChartEngine NullPointerExeption on XYSeries.add(x,y) method
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    <p>Hi i'm trying to implement aChartEngine library, when i add values in code (like in this tutorial <a href="http://www.javacodegeeks.com/2012/12/achartengine-a-charting-library-for-android-applications.html" rel="nofollow">by JavaCodeGeeks</a> ) it works perfectly but if I use a function the application crash and gives NullPointerExepction on mCurrentSeries.add(x, y). When i debug to see whats the problem mCurrentSeries.add(x,y) is repeated twice (in the same cycle) and then crash.</p> <p>This is the class</p> <pre><code>package com.example.achartengine; import org.achartengine.ChartFactory; import org.achartengine.GraphicalView; import org.achartengine.model.XYMultipleSeriesDataset; import org.achartengine.model.XYSeries; import org.achartengine.renderer.XYMultipleSeriesRenderer; import org.achartengine.renderer.XYSeriesRenderer; import com.towel.math.Expression; import android.os.Bundle; import android.app.Activity; import android.view.Menu; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.LinearLayout; public class MainActivity extends Activity { private GraphicalView mChart; private XYMultipleSeriesDataset mDataset = new XYMultipleSeriesDataset(); private XYMultipleSeriesRenderer mRenderer = new XYMultipleSeriesRenderer(); private XYSeries mCurrentSeries; private XYSeriesRenderer mCurrentRenderer; private Expression function; private EditText textFunction; public void initChart() { mCurrentSeries = new XYSeries("Sample Data"); mDataset.addSeries(mCurrentSeries); mCurrentRenderer = new XYSeriesRenderer(); mRenderer.addSeriesRenderer(mCurrentRenderer); } View.OnClickListener handler = new View.OnClickListener() { @Override public void onClick(View v) { addGraphData(); } }; private void addGraphData(){ String f = textFunction.getText().toString(); function = new Expression(f); Double y; for (int x = 0; x &lt; 15; x++){ function.setVariable("x", x); y = function.resolve(); mCurrentSeries.add(x, y); } LinearLayout layout = (LinearLayout) findViewById(R.id.chart); if(mChart==null){ initChart(); mChart = ChartFactory.getCubeLineChartView(this, mDataset, mRenderer, 0.3f); layout.addView(mChart); } else { mChart.repaint(); } } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Button draw = (Button) findViewById(R.id.buttonDraw); draw.setOnClickListener(handler); textFunction = (EditText) findViewById(R.id.textFunction); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } } </code></pre> <p>and this is the logcat</p> <pre><code>03-10 08:11:24.609: D/AndroidRuntime(2450): Shutting down VM 03-10 08:11:24.609: W/dalvikvm(2450): threadid=1: thread exiting with uncaught exception (group=0x40a71930) 03-10 08:11:24.619: E/AndroidRuntime(2450): FATAL EXCEPTION: main 03-10 08:11:24.619: E/AndroidRuntime(2450): java.lang.NullPointerException 03-10 08:11:24.619: E/AndroidRuntime(2450): at com.example.achartengine.MainActivity.addGraphData(MainActivity.java:54) 03-10 08:11:24.619: E/AndroidRuntime(2450): at com.example.achartengine.MainActivity.access$0(MainActivity.java:46) 03-10 08:11:24.619: E/AndroidRuntime(2450): at com.example.achartengine.MainActivity$1.onClick(MainActivity.java:42) 03-10 08:11:24.619: E/AndroidRuntime(2450): at android.view.View.performClick(View.java:4204) 03-10 08:11:24.619: E/AndroidRuntime(2450): at android.view.View$PerformClick.run(View.java:17355) 03-10 08:11:24.619: E/AndroidRuntime(2450): at android.os.Handler.handleCallback(Handler.java:725) 03-10 08:11:24.619: E/AndroidRuntime(2450): at android.os.Handler.dispatchMessage(Handler.java:92) 03-10 08:11:24.619: E/AndroidRuntime(2450): at android.os.Looper.loop(Looper.java:137) 03-10 08:11:24.619: E/AndroidRuntime(2450): at android.app.ActivityThread.main(ActivityThread.java:5041) 03-10 08:11:24.619: E/AndroidRuntime(2450): at java.lang.reflect.Method.invokeNative(Native Method) 03-10 08:11:24.619: E/AndroidRuntime(2450): at java.lang.reflect.Method.invoke(Method.java:511) 03-10 08:11:24.619: E/AndroidRuntime(2450): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 03-10 08:11:24.619: E/AndroidRuntime(2450): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 03-10 08:11:24.619: E/AndroidRuntime(2450): at dalvik.system.NativeStart.main(Native Method) </code></pre>
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    1. COWhat is on line no MainActivity.java:54.
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    2. COAre you sure `initChart` is called before `onClick`? Maybe `mCurrentSeries` is null when accessing it?
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    3. CO@TGMCians mCurrentSeries.add(x, y);
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