MpAndroidChart : IndexOutOfBoundsException

Question

在应用程序im获取WIFI List<ScanResults>数据和试图更新图表，但有些事情不顺利，和应用程序抛出异常java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0，我尝试了许多代码组合从MpAndroidChart，但没有解决问题.为什么会发生这种事？

WiFi ScanResults :广播接收机

public class Receiver extends BroadcastReceiver {

    @SuppressWarnings("ConstantConditions")
    @Override
    public void onReceive(Context context, Intent intent) {

        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    List<ScanResult> results = mWifiManager.getScanResults();
                    ArrayList<String> lista_bssid_e_skanuar = new ArrayList<>();
                    ArrayList<String> lista_bssid_lista_skanuar = new ArrayList<>();

                    //boolean channel_width_supported = false;

                    for (ScanResult result1 : results) {

                        final String SSID = result1.SSID;
                        final String channel = String.valueOf(ieee80211_frequency_to_channel(result1.frequency));
                        final String frequency = String.valueOf(result1.frequency);
                        final String BSSID = result1.BSSID;
                        final String capabilities = result1.capabilities;
                        final String signal = String.valueOf(result1.level);
                        String security = "FREE";
                        int channel_width;
                        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                            //channel_width_supported = true;
                            int freq1 = result1.centerFreq0;
                            int freq2 = result1.centerFreq1;
                            int channel_width_freq;
                            if (freq1 - freq2 < 0) {
                                channel_width_freq = freq2 - freq1;
                            } else {
                                channel_width_freq = freq1 - freq2;
                            }

                            if ((Integer.parseInt(frequency) - channel_width_freq) <= 0) {
                                channel_width = channel_width_freq - Integer.parseInt(frequency);
                            } else {
                                channel_width = Integer.parseInt(frequency) - channel_width_freq;
                            }

                            if (channel_width != 20 && channel_width != 40 && channel_width == 60 && channel_width != 80 && channel_width != 160) {
                                channel_width = 21;
                            }
                        } else {
                            //channel_width_supported = false;
                            channel_width = 21;
                        }

                        final int finalChannel_width = channel_width;
                        if (capabilities.contains("WPA")) {
                            security = "WPA";
                        }
                        if (capabilities.contains("WPA2")) {
                            security = "WPA2";
                        }
                        if (capabilities.contains("WEP")) {
                            security = "WEP";
                        }
                        final String finalSecurity = security;

                        if (!BSSID.equals("00:00:00:00:00:00")) {
                            lista_bssid_e_skanuar.add(SSID + "/" + channel + "/" + frequency + "/" + BSSID + "/" + capabilities + "/" + signal + "/" + finalSecurity + "/" + finalChannel_width);
                            lista_bssid_lista_skanuar.add(BSSID);
                        }
                    }

                    synchronized (_lock) {
                        for (int a = 0; a < lista_bssid_e_skanuar.size(); a++) {
                            String[] TE_DHENAT = lista_bssid_e_skanuar.get(a).split("/");
                            final String SSID_LISTA = TE_DHENAT[0];
                            final String CHANNEL_LISTA = TE_DHENAT[1];
                            final String BSSID_LISTA = TE_DHENAT[3];
                            final String SIGNAL_LISTA = TE_DHENAT[5];
                            final int kanali = Integer.parseInt(CHANNEL_LISTA);

                            int signal = Integer.parseInt(SIGNAL_LISTA) + 100;
                            if (signal > 70) {
                                signal = 70;
                            }

                            if (!lista_bssid_lista.contains(BSSID_LISTA)) {
                                lista_bssid_lista.add(BSSID_LISTA);
                                addEntry(kanali - 2, 0, a, SSID_LISTA);
                                addEntry(kanali, signal, a, SSID_LISTA);
                                addEntry(kanali + 2, 0, a, SSID_LISTA);
                            } else {
                                for (int i = 0; i < lista_bssid_lista.size(); i++) {
                                    if (!lista_bssid_lista_skanuar.contains(lista_bssid_lista.get(i))) {

//MAYBE EXCEPTION HAPPENING HERE ??
                                        final int finalSignal1 = signal;
                                        final int finalI = i;
                                        removeEntry(kanali, finalSignal1, finalI);
                                        addEntry(kanali - 2, 0, finalI, SSID_LISTA);
                                        addEntry(kanali, 0, finalI, SSID_LISTA);
                                        addEntry(kanali + 2, 0, finalI, SSID_LISTA);
                                    } else {

// OR HERE ????
                                        final int finalSignal = signal;
                                        final int finalA = a;
                                        removeEntry(kanali, finalSignal, finalA);

                                        addEntry(kanali - 2, 0, finalA, SSID_LISTA);
                                        addEntry(kanali, finalSignal, finalA, SSID_LISTA);
                                        addEntry(kanali + 2, 0, finalA, SSID_LISTA);
                                    }
                                }
                            }
                        }
                    }
                }catch (Exception i){
                    Thread.currentThread().interrupt();
                }
            }
        }).start();
    }
}

添加条目方法:

private synchronized void addEntry(float kanali, float sinjali, int indexi, String emri) {
    LineData data = mwifichart.getData();
    ILineDataSet set = data.getDataSetByIndex(indexi);
    if (set == null) {
        set = createSet(emri);
        data.addDataSet(set);
    }
    data.addEntry(new Entry(kanali, sinjali), indexi);
    data.notifyDataChanged();
    mwifichart.notifyDataSetChanged();
    getActivity().runOnUiThread(new Runnable() {
        @Override
        public void run() {
            mwifichart.invalidate();
        }
    });
}

删除条目方法:

private synchronized void removeEntry(float x_value,float y_value, int indexi) {
    try {
        LineData data = mwifichart.getData();
        if (data != null) {
            ILineDataSet set = data.getDataSetByIndex(indexi);
            if (set != null) {
                data.removeEntry(x_value - 2, indexi);
                data.removeEntry(x_value + 0, indexi);
                data.removeEntry(x_value + 2, indexi);
                data.notifyDataChanged();
                mwifichart.notifyDataSetChanged();
            }
        }
    }catch (Exception I){     TastyToast.makeText(getContext(),I.getMessage(),TastyToast.LENGTH_SHORT,TastyToast.ERROR);
    }
}

我得到了这个异常，应用程序立即崩溃，尝试了许多代码组合，但什么也没有.

java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
                                                   at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:260)
                                                   at java.util.ArrayList.get(ArrayList.java:313)
                                                   at com.github.mikephil.charting.data.DataSet.getEntryForIndex(DataSet.java:286)
                                                   at com.github.mikephil.charting.utils.Transformer.generateTransformedValuesLine(Transformer.java:184)
                                                   at com.github.mikephil.charting.renderer.LineChartRenderer.drawValues(LineChartRenderer.java:547)
                                                   at com.github.mikephil.charting.charts.BarLineChartBase.onDraw(BarLineChartBase.java:263)

更新:

如果代码运行在UI线程上，那么异常似乎不会发生，但不确定这一点，只是它不再抛出异常？

示例

getActivity().runOnUiThread(new Runnable() {
                                                @Override
                                                public void run() {
                                                    removeEntry(kanali, finalSignal, finalA);

                                                    addEntry(kanali - 2, 0, finalA, SSID_LISTA);
                                                    addEntry(kanali, finalSignal, finalA, SSID_LISTA);
                                                    addEntry(kanali + 2, 0, finalA, SSID_LISTA);
                                                }
                                            });

Answer 1

这个问题在Github项目中得到了跟进：https://github.com/PhilJay/MPAndroidChart/issues/2450

这似乎只发生在线条图上。

如果没有要显示的值，则可能的解决方案似乎是清除图表：

if (values.isEmpty()) {
       chart.clear();
} else {
      // set data
      chart.setData(data);
}

我也有同样的问题，并将很快部署此修复程序，如果此修复程序不起作用，我将进行更新。

Answer 2

我也有同样的问题，但我只是清理了图表之前，把任何数据。

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

Answer 3

您应该自定义一个简单的ChartRenderer，避免在图表为空时绘制。然后，你把它添加到你的图表中。

chart.setRenderer(new CustomLineChartRenderer(chart,chart.getAnimator(),chart.getViewPortHandler()));

public class CustomLineChartRenderer extends LineChartRenderer {
public CustomLineChartRenderer(LineDataProvider chart, ChartAnimator animator, ViewPortHandler viewPortHandler) {
    super(chart, animator, viewPortHandler);
}

@Override
protected boolean shouldDrawValues(IDataSet set) {
    return super.shouldDrawValues(set) && set.getEntryCount() > 0;
 }
}