饼图中不显示饼图（Android）

Question

我正在开发一个andorid应用程序，并且在此应用程序中，我试图通过选项卡片段之一显示饼图。但它显示“无图表数据”。当我尝试在一个活动中做同样的事情时，它完美地显示出来。我使用“MPAndroidChart”作为参考。请帮助。 在此先感谢！

这是我fragment.class

import android.graphics.Color; 
import android.graphics.Typeface; 
import android.net.Uri; 

import android.os.Bundle; 
import android.text.SpannableString; 
import android.text.style.ForegroundColorSpan; 
import android.text.style.RelativeSizeSpan; 
import android.text.style.StyleSpan; 
import android.util.Log; 
import android.view.InflateException; 
import android.view.LayoutInflater; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.SeekBar; 
import android.widget.TextView; 
import com.github.mikephil.charting.charts.PieChart; 
import com.github.mikephil.charting.components.Legend; 
import com.github.mikephil.charting.data.Entry; 


import com.github.mikephil.charting.data.PieData; 
import com.github.mikephil.charting.data.PieDataSet; 


import com.github.mikephil.charting.utils.ColorTemplate; 

import java.util.ArrayList; 






public class overview extends android.support.v4.app.Fragment { 
private static final String ARG_PARAM1 = "param1"; 
private static final String ARG_PARAM2 = "param2"; 
private static View rootView; 
private OnFragmentInteractionListener mListener; 
private SeekBar mSeekBarX, mSeekBarY; 
private TextView tvX, tvY; 
private PieChart mChart; 

private Typeface tf; 



public overview() { 
    // Required empty public constructor 
} 

//String param1, String param2 
public static overview newInstance() { 
    overview fragment = new overview(); 
    Bundle args = new Bundle(); 
    // args.putString(ARG_PARAM1, param1); 
    //args.putString(ARG_PARAM2, param2); 
    fragment.setArguments(args); 
    return fragment; 
} 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 

    if (getArguments() != null) { 

    } 
} 
public View onCreateView(LayoutInflater inflater, final ViewGroup container, 
         Bundle savedInstanceState) { 
    // Inflate the layout for this fragment 
    View view = inflater.inflate(R.layout.overview, container, false); 

    PieChart pieChart = (PieChart) findViewById(R.id.chart); 

    ArrayList<Entry> entries = new ArrayList<>(); 
    entries.add(new Entry(4f, 0)); 
    entries.add(new Entry(8f, 1)); 
    entries.add(new Entry(6f, 2)); 
    entries.add(new Entry(12f, 3)); 
    entries.add(new Entry(18f, 4)); 
    entries.add(new Entry(9f, 5)); 

    PieDataSet dataset = new PieDataSet(entries, "# of Calls"); 

    ArrayList<String> labels = new ArrayList<String>(); 
    labels.add("January"); 
    labels.add("February"); 
    labels.add("March"); 
    labels.add("April"); 
    labels.add("May"); 
    labels.add("June"); 

    PieData data = new PieData(labels, dataset); 
    dataset.setColors(ColorTemplate.COLORFUL_COLORS); // 
    pieChart.setDescription("Description"); 
    pieChart.setData(data); 

    pieChart.animateY(5000); 

    pieChart.saveToGallery("/sd/mychart.jpg", 85); // 85 is the quality of 
    the image 




    if (rootView != null) { 
     ViewGroup parent = (ViewGroup) rootView.getParent(); 
     if (parent != null) 
      parent.removeView(rootView); 
    } 
    try { 
     rootView = inflater.inflate(R.layout.overview, container, false); 

    } catch (InflateException e) { 
    /* map is already there, just return view as it is */ 
    } 
    return rootView; 
} 

private SpannableString generateCenterText() { 
    SpannableString s = new SpannableString("Revenues\nQuarters 2015"); 
    s.setSpan(new RelativeSizeSpan(2f), 0, 8, 0); 
    s.setSpan(new ForegroundColorSpan(Color.GRAY), 8, s.length(), 0); 
    return s; 
} 


@Override 
public void onDetach() { 
    super.onDetach(); 
    mListener = null; 
} 

public interface OnFragmentInteractionListener { 
    // TODO: Update argument type and name 
    void onFragmentInteraction(Uri uri); 
} 

} 

这是我的xml文件：

 <com.github.mikephil.charting.charts.PieChart 
      android:id="@+id/chart" 
      android:layout_width="300dp" 
      android:layout_height="300dp" /> 

Answer 1

其实你的声明是错误的PiChart.Declare它的正确像这样;

View view = inflater.inflate(R.layout.overview, container, false); 

PieChart pieChart = (PieChart)view.findViewById(R.id.chart); 

Answer 2

因为你初始化它是错误的。这样

PieChart pieChart = (PieChart) findViewById(R.id.chart); 

改变这一行

PieChart pieChart = (PieChart) view.findViewById(R.id.chart);