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POLoop to fill an array for use in listview (fill array from txt file strings)
 

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  1. POLoop to fill an array for use in listview (fill array from txt file strings)
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    <p>I am trying to fill an array for use in a listview in android. I want the array to be filled with data stored in several .txt files on the sdcard. I have an Int names Mx that tells the loop how many times to run (well thats what i would like it to do). The value Mx is also the number of entries required in the array.</p> <p>I am currently using this code but it doesnt work:</p> <pre><code> public void arrayload() { ///////////////////////////////////working here///////////////////////////////// //new looping code for (int i=1; i&lt;=Mx; i++){ try{ String fileName = String.valueOf(i) +".txt"; File myFile = new File("/sdcard/mx/" +fileName); FileInputStream fIn = new FileInputStream(myFile); BufferedReader myReader = new BufferedReader( new InputStreamReader(fIn)); String aDataRow = ""; String aBuffer = ""; while ((aDataRow = myReader.readLine()) != null) { aBuffer += aDataRow + "\n"; } String[] lvdata = new String[Mx]; lvdata[i] = aBuffer; ArrayAdapter&lt;String&gt; adapter = new ArrayAdapter&lt;String&gt;(this, R.layout.logbooklayout, lvdata); lv1.setAdapter(adapter); lv1.scrollTo(0, mxlv); // set the listview at a sensible point } catch (Exception e) { Toast.makeText(getBaseContext(), e.getMessage(), Toast.LENGTH_SHORT).show(); } } </code></pre> <p>I have previously been hardcoding each entry into the array but am trying to tidy the code up so it loops based on the value Mx. I know the array and listview work fine if i manually fill them, wheni use the code below the app crashes.</p> <p>Logcat output is</p> <pre><code>03-02 16:41:23.888: E/AndroidRuntime(31497): FATAL EXCEPTION: main 03-02 16:41:23.888: E/AndroidRuntime(31497): java.lang.NullPointerException 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:394) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.widget.AbsListView.obtainView(AbsListView.java:2159) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.widget.ListView.measureHeightOfChildren(ListView.java:1246) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.widget.ListView.onMeasure(ListView.java:1158) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.view.View.measure(View.java:15513) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:645) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:425) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.view.View.measure(View.java:15513) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4827) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.view.View.measure(View.java:15513) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.widget.LinearLayout.measureVertical(LinearLayout.java:847) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.view.View.measure(View.java:15513) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4827) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 03-02 16:41:23.888: E/AndroidRuntime(31497): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2176) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.view.View.measure(View.java:15513) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1874) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1089) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1265) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.view.Choreographer.doCallbacks(Choreographer.java:562) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.view.Choreographer.doFrame(Choreographer.java:532) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.os.Handler.handleCallback(Handler.java:725) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.os.Handler.dispatchMessage(Handler.java:92) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.os.Looper.loop(Looper.java:137) 03-02 16:41:23.888: E/AndroidRuntime(31497): at android.app.ActivityThread.main(ActivityThread.java:5191) 03-02 16:41:23.888: E/AndroidRuntime(31497): at java.lang.reflect.Method.invokeNative(Native Method) 03-02 16:41:23.888: E/AndroidRuntime(31497): at java.lang.reflect.Method.invoke(Method.java:511) 03-02 16:41:23.888: E/AndroidRuntime(31497): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795) 03-02 16:41:23.888: E/AndroidRuntime(31497): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562) 03-02 16:41:23.888: E/AndroidRuntime(31497): at dalvik.system.NativeStart.main(Native Method) </code></pre> <p>Any help with this is really welcome. I am just cutting my teeth with Java so my code is in need of improving lots! </p> <p>Thanks</p>
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