如何在Android中使用Achartengine库在片段内使用图表？

Question

我有一个活动3ChartPerTabActivity我有3个选项卡片段与Viepager.Each片段视图有不同的颜色.到目前为止工作.

我尝试将PieChart添加到第一个选项卡片段布局时出现问题...我想为每个选项卡创建一个图表.例如,第一个选项卡,饼图等

我决定使用Achartenginelibrary.I试过但我得到了"NullPointerException".

这是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>

这是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);

///////////////////////////这里我有空指针异常///////////////// ////

// 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);
    }
}

这是一个截图:

Answer 1

getView在AFTER onCreateView完成后才能工作:http: //developer.android.com/reference/android/app/Fragment.html#getView()

使用View您膨胀的onCreateView作为起点,在您还在的时候"查找"您的其他视图onCreateView,而不是getView().

例如:

View view = (LinearLayout) inflater.inflate(R.layout.tab_frag1_layout,
                container, false);
LinearLayout chartContainer = (LinearLayout) view.findViewById(
        R.id.chart_container);
...
return view;

(假设"tab_frag1_layout"里面有"chart_container"布局.)