Eu tenho uma atividade 3ChartPerTabActivity onde eu tenho 3 abas fragmento com Viepager.Each vista fragmento tem cor diferente.Ate agora está funcionando.

Meu problema ocorre quando eu tento adicionar um PieChart ao layout primeiro fragmento guia ... Eu quero fazer um gráfico por guia.Por exemplo, primeiro guia um gráfico de pizza e.t.c.

Eu decidi usarAchartengine biblioteca.Eu tentei, mas eu recebo"NullPointerException".

Aqui está o tab_frag1_layout.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="match_parent"
    android:background="#FF0000"
    android:orientation="vertical" >

        <LinearLayout
            android:id="@+id/chart_container"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content">
        </LinearLayout>

    </LinearLayout>

Aqui está o Tab1Fragment:

import java.text.DecimalFormat;

import org.achartengine.ChartFactory;
import org.achartengine.GraphicalView;
import org.achartengine.model.CategorySeries;
import org.achartengine.model.SeriesSelection;
import org.achartengine.renderer.DefaultRenderer;
import org.achartengine.renderer.SimpleSeriesRenderer;

import android.graphics.Color;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.Toast;

public class Tab1Fragment extends Fragment {

    private GraphicalView mChartView;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        if (container == null) {
            return null;
        }

        // Pie Chart Slice Names
        final String[] status = new String[] { "Normal", "High", "Over" };

        // Pie Chart Slice Values
        double[] distribution = { 6, 3, 1 };

        // Color of each Pie Chart Slices
        int[] colors = { Color.GREEN, Color.YELLOW, Color.RED };

                // Instantiating CategorySeries to plot Pie Chart
        CategorySeries distributionSeries = new CategorySeries(" General ");
        for (int i = 0; i < distribution.length; i++) {

            // Adding a slice with its values and name to the Pie Chart
            distributionSeries.add(status[i], distribution[i]);
        }

        // Instantiating a renderer for the Pie Chart
        DefaultRenderer defaultRenderer = new DefaultRenderer();
        for (int i = 0; i < distribution.length; i++) {
            SimpleSeriesRenderer seriesRenderer = new SimpleSeriesRenderer();
            seriesRenderer.setColor(colors[i]);
            seriesRenderer.setDisplayChartValues(true);

            // Adding the renderer of a slice to the renderer of the pie chart
            defaultRenderer.addSeriesRenderer(seriesRenderer);
        }

        defaultRenderer.setChartTitle("General");
        defaultRenderer.setChartTitleTextSize(20);
        defaultRenderer.setZoomButtonsVisible(true);

/////////////////////////// Aqui eu tenho exceção ponteiro nulo ///////////////// ////

// Getting a reference to view group linear layout chart_container
LinearLayout chartContainer = (LinearLayout) getView().findViewById(
        R.id.chart_container);

////////////////////////////////////////////////// //////////////////////////////////

// Getting PieChartView to add to the custom layout
        mChartView = ChartFactory.getPieChartView(getActivity(),
                distributionSeries, defaultRenderer);

        // Adding the pie chart to the custom layout
        chartContainer.addView(mChartView);

        return (LinearLayout) inflater.inflate(R.layout.tab_frag1_layout,
                container, false);
    }
}

Aqui está uma captura de tela: