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我试图摆脱那个错误，但我没有看到任何错误（对我来说）；有人也遇到了这个问题，但这是给布局的错误 ID：addView 导致 NullPointerException

我从http://www.javaadvent.com/2012/12/achartengine-charting-library-for.html 获取了一个简单的代码示例

public class LineGraph extends Activity {

    private GraphicalView mChart;
    private XYMultipleSeriesDataset mDataset = new XYMultipleSeriesDataset();
    private XYMultipleSeriesRenderer mRenderer = new XYMultipleSeriesRenderer();
    private XYSeries mCurrentSeries;
    private XYSeriesRenderer mCurrentRenderer;

    private void initChart() {
        mCurrentSeries = new XYSeries("Sample Data");
        mDataset.addSeries(mCurrentSeries);
        mCurrentRenderer = new XYSeriesRenderer();
        mRenderer.addSeriesRenderer(mCurrentRenderer);
    }

    private void addSampleData() {
        mCurrentSeries.add(1, 2);
        mCurrentSeries.add(2, 3);
        mCurrentSeries.add(3, 2);
        mCurrentSeries.add(4, 5);
        mCurrentSeries.add(5, 4);
    }

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.graph);
    }

    protected void onResume() {
        super.onResume();
        if (mChart == null) {
            LinearLayout layout = (LinearLayout) findViewById(R.id.chart);
            initChart();
            addSampleData();
            mChart = ChartFactory.getCubeLineChartView(this, mDataset, mRenderer, 0.3f);

         // Here is the problem => layout.addView(mChart);

        } else {
            mChart.repaint();
        }
    }
}

和我的 XML 文件：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

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

    </LinearLayout>

</LinearLayout>

可能是我错过了一个明显的错误，但是 addView() 给了我一个 nullPointerException，请有人可以告诉我我做错了什么？

编辑：和堆栈跟踪

05-17 14:37:05.830: E/SensorManager(6703): thread start
05-17 14:37:06.885: E/SpannableStringBuilder(6703): SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
05-17 14:37:06.885: E/SpannableStringBuilder(6703): SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
05-17 14:37:28.800: E/AndroidRuntime(6703): FATAL EXCEPTION: main
05-17 14:37:28.800: E/AndroidRuntime(6703): java.lang.RuntimeException: Unable to resume activity {com.smartdroid/com.smartdroid.LineGraph}: java.lang.NullPointerException
05-17 14:37:28.800: E/AndroidRuntime(6703):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2616)
05-17 14:37:28.800: E/AndroidRuntime(6703):     at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2644)
05-17 14:37:28.800: E/AndroidRuntime(6703):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2130)
05-17 14:37:28.800: E/AndroidRuntime(6703):     at android.app.ActivityThread.access$600(ActivityThread.java:140)
05-17 14:37:28.800: E/AndroidRuntime(6703):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1227)
05-17 14:37:28.800: E/AndroidRuntime(6703):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-17 14:37:28.800: E/AndroidRuntime(6703):     at android.os.Looper.loop(Looper.java:137)
05-17 14:37:28.800: E/AndroidRuntime(6703):     at android.app.ActivityThread.main(ActivityThread.java:4898)
05-17 14:37:28.800: E/AndroidRuntime(6703):     at java.lang.reflect.Method.invokeNative(Native Method)
05-17 14:37:28.800: E/AndroidRuntime(6703):     at java.lang.reflect.Method.invoke(Method.java:511)
05-17 14:37:28.800: E/AndroidRuntime(6703):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
05-17 14:37:28.800: E/AndroidRuntime(6703):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
05-17 14:37:28.800: E/AndroidRuntime(6703):     at dalvik.system.NativeStart.main(Native Method)
05-17 14:37:28.800: E/AndroidRuntime(6703): Caused by: java.lang.NullPointerException
05-17 14:37:28.800: E/AndroidRuntime(6703):     at com.smartdroid.LineGraph.onResume(LineGraph.java:64)
05-17 14:37:28.800: E/AndroidRuntime(6703):     at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1188)
05-17 14:37:28.800: E/AndroidRuntime(6703):     at android.app.Activity.performResume(Activity.java:5280)
05-17 14:37:28.800: E/AndroidRuntime(6703):     at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2606)
05-17 14:37:28.800: E/AndroidRuntime(6703):     ... 12 more
05-17 14:38:45.465: E/SensorManager(8335): thread start
05-17 14:38:46.630: E/SpannableStringBuilder(8335): SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
05-17 14:38:46.630: E/SpannableStringBuilder(8335): SPAN_EXCLUSIVE_EXCLUSIVE spans cannot have a zero length
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1 回答 1

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伙计们，这是我的错：我将图表布局添加到另一个 XML 中，与调用 onCreate() 时设置的布局不同。对不起所有的混乱，谢谢你们的好意

于 2013-05-17T12:59:04.660 回答