(对不起,放了太多代码,但是如果我没有写,那将使事情难以解释)
无论如何,我做了一条指令来从mysql数据库中获取一些数据:
//asynctask
private class JsonReadTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... params) {
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
nameValuePairs.add(new BasicNameValuePair("fro", fr));
nameValuePairs.add(new BasicNameValuePair("too",to));
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(params[0]);
try {
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
jsonResult = inputStreamToString(
response.getEntity().getContent()).toString();
}
catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
private StringBuilder inputStreamToString(InputStream is) {
String rLine = "";
StringBuilder answer = new StringBuilder();
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
try {
while ((rLine = rd.readLine()) != null) {
answer.append(rLine);
}
}
catch (IOException e) {
// e.printStackTrace();
Toast.makeText(getApplicationContext(),
"Error..." + e.toString(), Toast.LENGTH_LONG).show();
}
return answer;
}
@Override
protected void onPostExecute(String result) {
try {
JSONObject jsonResponse = new JSONObject(jsonResult);
JSONArray jsonMainNode = jsonResponse.optJSONArray("energystatistic");
for (int i = 0; i < jsonMainNode.length(); i++) {
JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
String kwh = jsonChildNode.optString("kwh");
s1 = addElement(s1, Integer.parseInt(kwh));
}
} catch (JSONException e) {
Toast.makeText(getApplicationContext(), "Error" + e.toString(), Toast.LENGTH_SHORT).show();
}
Toast.makeText(Plot.this, "Begin plot: " + String.valueOf(s1.length) + " Entries", Toast.LENGTH_SHORT).show();
// Turn the above arrays into XYSeries':
XYSeries series1 = new SimpleXYSeries(Arrays.asList(s1), SimpleXYSeries.ArrayFormat.Y_VALS_ONLY,"Series1");
LineAndPointFormatter series1Format = new LineAndPointFormatter(Color.RED, Color.GREEN, Color.BLUE, null);
// add a new series' to the xyplot:
plot.addSeries(series1, series1Format);
// reduce the number of range labels
plot.setTicksPerRangeLabel(3);
plot.getGraphWidget().setDomainLabelOrientation(-45);
Toast.makeText(Plot.this, "Plotted", Toast.LENGTH_SHORT).show();
}
}
// end async task
这里的问题是以下代码被忽略或其他原因:
// Turn the above arrays into XYSeries':
XYSeries series1 = new SimpleXYSeries(Arrays.asList(s1),SimpleXYSeries.ArrayFormat.Y_VALS_ONLY,"Series1");
LineAndPointFormatter series1Format = new LineAndPointFormatter(Color.RED, Color.GREEN, Color.BLUE, null);
// add a new series' to the xyplot:
plot.addSeries(series1, series1Format);
// reduce the number of range labels
plot.setTicksPerRangeLabel(3);
plot.getGraphWidget().setDomainLabelOrientation(-45);
我运行了一个调试器来检查那些行,程序会运行它们,但是该图似乎不受影响。该图保持空白,我不明白为什么。我需要使用其他方法来运行此程序吗?
如果我将其放在onCreate方法中,该图会显示一些更改,但这些点仍然根本不会绘制。通过JSon从数据库获取信息后,数组s1 []确实具有数据(所有int号)。
最佳答案
完成对图形的修改后,尝试调用plot.redraw()
。