我是AChartEngine的新手。我试图从远程数据库中检索JSON数据并将其插入AchartEngine条形图中。我可以成功获取数据。但是，我很难将其插入图表中。图表没有获取我的数据。当我硬编码或放一个随机数时，它会显示在图表上，但当我尝试从数据库中包含数据时，它会显示一个空白页面。我发布了我的代码。任何帮助，将不胜感激。我试图在＆＃34; X＆＃34;轴和数量在＆＃34; Y＆＃34;轴。
public class BarGraphActivity extends AppCompatActivity {
private GraphicalView mChart;
private TimeSeries transactionSeries;
private XYMultipleSeriesDataset dataset;
private XYSeriesRenderer transactionRenderer;
private XYMultipleSeriesRenderer multiRenderer;
//JSON node name
private static final String TAG_TYPE = "type";
private static final String TAG_AMOUNT = "amount";
private static final String TAG_CATEGORY = "category";
private static final String TAG_DESC = "desc";
private static final String TAG_DATE = "date";
private static final String TAG_SUCCESS = "success";
static final String FETCH_URL = "my_url";
String amount = null;
String desc = null;
String type = null;
String date = null;
String category = null;
ProgressDialog pDialog;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_bar_graph);
//showTransaction();
//settingup bar chart
//start plotting chart
new ChartTask().execute();
}
public void setupChart(){
//creating an Timeseries for Transactions
transactionSeries = new TimeSeries("Transactions");
//creating a dataset to hold each series
dataset = new XYMultipleSeriesDataset();
//adding transactionseries to the dataset
dataset.addSeries(transactionSeries);
//Creating a XYMultipleSeriesRenderer to customize transaction series
transactionRenderer = new XYSeriesRenderer();
transactionRenderer.setColor(Color.GREEN);
//transactionRenderer.setPointStyle(PointStyle.CIRCLE);
transactionRenderer.setFillPoints(true);
transactionRenderer.setLineWidth(4);
transactionRenderer.setDisplayChartValues(false);
// Creating a XYMultipleSeriesRenderer to customize the whole chart
multiRenderer = new XYMultipleSeriesRenderer();
multiRenderer.setChartTitle("Transaction Trends");
multiRenderer.setXTitle("Date");
multiRenderer.setYTitle("Amount");
//multiRenderer.setZoomButtonsVisible(true);
multiRenderer.setXAxisMin(0);
multiRenderer.setXAxisMax(10);
multiRenderer.setYAxisMin(0);
multiRenderer.setYAxisMax(10);
multiRenderer.setBarSpacing(2);
// Adding transactionRenderer to multipleRenderer
// Note: The order of adding dataseries to dataset and renderers to multipleRenderer
// should be same
multiRenderer.addSeriesRenderer(transactionRenderer);
// Getting a reference to LinearLayout of the bar graph activity Layout
LinearLayout chartContainer = (LinearLayout) findViewById(R.id.chart_container);
mChart = (GraphicalView) ChartFactory.getBarChartView(getBaseContext(), dataset, multiRenderer, BarChart.Type.DEFAULT);
// Adding the Line Chart to the LinearLayout
chartContainer.addView(mChart);
}
private class ChartTask extends AsyncTask<String, String, String> {
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(BarGraphActivity.this);
pDialog.setMessage("Loading data. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected String doInBackground(String... String) {
//int i = 0;
//String[] amount = new String[];
try {
URL url = new URL(FETCH_URL);
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.connect();
int responsecode = urlConnection.getResponseCode();
if(responsecode == HttpURLConnection.HTTP_OK){
BufferedReader br = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
StringBuilder sb = new StringBuilder();
String line;
while ((line = br.readLine()) != null){
sb.append(line);
}
br.close();
return sb.toString();
}
} catch (ProtocolException e) {
e.printStackTrace();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
pDialog.dismiss();
try {
//get JSONObject from JSONArray of String
JSONArray result = new JSONArray(s);
JSONObject jsonObject = null;
String[] values = new String[2];
//loop through the array and break the JSONObject into String
for(int i = 0; i<result.length(); i++) {
jsonObject = result.getJSONObject(i);
amount = jsonObject.getString(TAG_AMOUNT);
desc = jsonObject.getString(TAG_DESC);
type = jsonObject.getString(TAG_TYPE);
//getting date as string from database
date = jsonObject.getString(TAG_DATE);
//System.out.println(date);
//write it in the db in a different format like Wednesday, July 12, 2016 12:00 PM
SimpleDateFormat readFormat = new SimpleDateFormat("EEEE, MMMM dd, yyyy hh:mm a");
//SimpleDateFormat writeFormat = new SimpleDateFormat("MMMM dd, yyyy");
//check it date string for null or empty string or else it will give Unparseable date: "" (at offset 0) error
if(!date.equalsIgnoreCase("")) {
try {
Date dt = readFormat.parse(date); //parse the date string in the read format
//String dtStr = writeFormat.format(dt);
//dt = writeFormat.parse(dtStr);
//System.out.println(dt);
Log.d("Date: ", date);
double amt = Double.valueOf(amount.replace(",", ""));
//System.out.println(amt);
Log.d("Amount: ", String.valueOf(amt));
setupChart();
transactionSeries.add(dt.getTime(),amt);
mChart.repaint();
} catch (ParseException e) {
e.printStackTrace();
}
}
else {
return;
}
}
}
catch (JSONException e){
e.printStackTrace();
} //catch (ParseException e) {
// e.printStackTrace();
// }
}
// Plotting generated data in the graph
/**@Override
protected void onProgressUpdate(Object... values) {
transactionSeries.add((Double) values[0], (Double) values[1]);
mChart.repaint();
}**/
}
以下是重试后数据的显示方式
D /日期:: 2015年7月29日星期三上午1:35
D / Amount :: 221.06
d /日期:: 2015年11月25日星期三下午3:27
D / Amount :: 275.7
答案 0 :(得分：0)
这里的方法＆＃34; setupChart（）＆＃34;，在通过asynctask＆＃34; new ChartTask（）。execute（）＆＃34;从webservice获取值之前调用。因此，没有获得绘制图表的值，或者可以说在绘制后得到的值。
解决方案：请调用方法＆＃34; setupChart（）＆＃34;在asynctask onpostexecute。