我正在尝试创建一个警报对话框，当在图表上绘制的值低于某个特定数字或高于某个特定数字时，该对话框将向用户显示一条消息。 我不知道我需要比较哪个变量，或者我是否需要进一步编辑现有代码..我认为它可能已经很简单了：
if(engineRPMlist <= 40)
{
//Then print message
}
但是事实并非如此。 帮助将不胜感激，因为我很困：）
/*
This class is used to graph the Data for the "Engine RPM" which
is retrieved from the Database. This retrieves the data from the database which is stored on
Firebase. This data is then used to plot the data on a LineChart. Alert Dialogs Pop up before
the graph appears and explains the data to the user, as well as stating if the data recorded is
normal readings or if there are variances present
*/
public class GraphEngineRPM extends Activity implements
OnChartGestureListener, OnChartValueSelectedListener
{
private static final String TAG = "GraphEngineRPM";
//Declaring the chart
private LineChart chart;
//Declaring progress dialog
private ProgressDialog progress;
//Array to hold Mass Airflow data from FireBase
ArrayList<Entry> engineRPMlist = new ArrayList<>();
//Variables
LineDataSet set1;
LineData data;
protected void onCreate(Bundle savedInstanceState)
{
/*This creates an Alert dialog on this screen, it also sets it so the user can cancel the message
for the Engine RPM information*/
AlertDialog.Builder builder = new AlertDialog.Builder(GraphEngineRPM.this);
builder.setCancelable(true);
//Setting the title and message from the string.xml
builder.setTitle(GraphEngineRPM.this.getString(R.string.engine_rpm_title));
builder.setMessage(GraphEngineRPM.this.getString(R.string.engine_rpm_def));
//When the user selects the Cancel button the page will redirect back to the VehicleSpec page
builder.setNegativeButton(GraphEngineRPM.this.getString(R.string.cancel), new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int whichButton) {
dialog.cancel();
Intent intent = new Intent(GraphEngineRPM.this, DataDisplay.class);
startActivity(intent);
}//End onClick()
});//End setNegativeButton()
builder.setPositiveButton(GraphEngineRPM.this.getString(R.string.Ok), new DialogInterface.OnClickListener()
{
@Override
public void onClick(DialogInterface dialog, int which)
{
}//End onClick()
});//End setPositiveButton()
builder.show();
super.onCreate(savedInstanceState);
//Sets the layout according to the XML file
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.activity_graph_engine_rpm);
//XML reference
chart = findViewById(R.id.linechart);
//Listens for on chart taps
chart.setOnChartGestureListener(GraphEngineRPM.this);
chart.setOnChartValueSelectedListener(GraphEngineRPM.this);
//Enable touch gestures
chart.setTouchEnabled(true);
//Enable scaling and dragging
chart.setDragEnabled(true);
chart.setScaleEnabled(false);
chart.setDrawGridBackground(false);
//Enable pinch zoom
chart.setPinchZoom(true);
//Background color
chart.setBackgroundColor(Color.LTGRAY);
//Setting YAxis
YAxis left = chart.getAxisLeft();
left.setAxisMinimum(20);
left.setAxisMinimum(0f);
left.setAxisMaximum(1500f);
left.setTextSize(13f);
left.enableGridDashedLine(10f, 10f, 0f);
YAxis left2 = chart.getAxisRight();
left2.setEnabled(false);
chart.getAxisRight().setEnabled(false);
//Value String
String[] vals = new String[] {"0s", "1s", "2s", "3s", "4s", "5s", "6s", "7s", "8s", "9s", "10s", "11s"};
//Legend object
Legend i = chart.getLegend();
//Customise legend
i.setTextSize(15f);
i.setForm(Legend.LegendForm.CIRCLE);
i.setTextColor(Color.BLACK);
//Setting XAis
XAxis x = chart.getXAxis();
x.setTextSize(13f);
x.setValueFormatter(new MyXAxisValueFormatter(vals));
x.setGranularity(1);
x.setPosition(XAxis.XAxisPosition.BOTTOM);
//Adding value to array as system will crash without
engineRPMlist.add(new Entry(0, 0));
engineRPMlist.add(new Entry(1, 0));
//Setting the line
set1 = new LineDataSet(engineRPMlist, "Engine RPM ");
set1.setFillAlpha(110);
set1.setColor(Color.RED);
set1.setLineWidth(3f);
set1.setValueTextSize(10f);
set1.setValueTextColor(Color.BLACK);
data = new LineData(set1);
chart.setData(data);
//Calls the downloadData()
downloadData();
//Change the chart when a change occurs
chart.notifyDataSetChanged();
//XML button
Button checkD = findViewById(R.id.checkdata);
//If the user taps the button
checkD.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
//ProgressDialog will appear stating that the data is being checked
progress = new ProgressDialog(GraphEngineRPM.this);
progress.setMax(100);
progress.setMessage("Checking...");
progress.setTitle("Checking Vehicle data");
progress.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
progress.show();
new Thread(new Runnable()
{
@Override
//When running
public void run()
{
try
{
//Whilst the progress dialog is less than or equal to the max
while (progress.getProgress() <= progress.getMax())
{
//Dialog will pause
Thread.sleep(200);
//Handler will retrieve the message of increments
handler.sendMessage(handler.obtainMessage());
//If the progress dialog is equal to the max
if (progress.getProgress() == progress.getMax())
{
//progressDialog will be shut
progress.dismiss();
//The AlertDialog will be opened
progress.setOnDismissListener(new DialogInterface.OnDismissListener()
{
@Override
public void onDismiss(DialogInterface dialog)
{
//CHECK IF VALUE IN BELOW/ABOVE CERTAIN NUMBER
showAlertDialog();
}//End onDismiss()
});//End OnDismissListener()
}//End if()
}//End while()
}//End try()
catch (Exception e)
{
e.printStackTrace();
}//End catch()
}//End run()
}).start();
}//End onClick()
@SuppressLint("HandlerLeak")
Handler handler = new Handler()
{
public void handleMessage (Message msg)
{
super.handleMessage(msg);
//Sets the value to increment by 3
progress.incrementProgressBy(3);
}//End handleMessage()
};//End Handler()
});//End OnClickListener()
}//End onCreate
public void showAlertDialog()
{
/*This creates an Alert dialog on this screen, it also sets it so the user can cancel the message
for the Mass Airflow rate information retrieved from the database*/
AlertDialog.Builder builder2 = new AlertDialog.Builder(GraphEngineRPM.this);
builder2.setCancelable(true);
//Setting the title and message from the string.xml
builder2.setTitle(GraphEngineRPM.this.getString(R.string.IMPORTANT));
builder2.setMessage(GraphEngineRPM.this.getString(R.string.airflow_info));
//When the user selects the Cancel button the page will redirect back to the VehicleSpec page
builder2.setNegativeButton(GraphEngineRPM.this.getString(R.string.cancel), new DialogInterface.OnClickListener()
{
@Override
public void onClick(DialogInterface dialog, int whichButton)
{
dialog.cancel();
Intent intent = new Intent(GraphEngineRPM.this, DataDisplay.class);
startActivity(intent); }//End onClick()
});//End setNegativeButton()
//If the user taps Ok
builder2.setPositiveButton(GraphEngineRPM.this.getString(R.string.Ok), new DialogInterface.OnClickListener()
{
@Override
public void onClick(DialogInterface dialog, int which)
{
}//End onClick()
});//End setPositiveButton()
//Show the Dialogs on screen
builder2.show();
}//End showAlertDialog()
//Downloads Data from FireBase
private void downloadData()
{
//ArrayAdapter
final ArrayAdapter<String> arrayAdapter = new ArrayAdapter<>(this,R.layout.activity_graph_engine_rpm);
Intent intent = getIntent();
final String vehicle_key = intent.getStringExtra("Vehicle_id");
Log.d(vehicle_key, "ENGINE RPM");
//Connecting into table "VehicleData" on the FireBase database
DatabaseReference database = FirebaseDatabase.getInstance().getReference("Vehicles").child(vehicle_key).child("VehiclesData");
//ChildEventListener allows child events to be listened for
database.addChildEventListener(new ChildEventListener()
{
public void onChildAdded(DataSnapshot dataSnapshot, String prevChildKey)
{
//Holds the Datasnapshot value of the database as type String
VehicleData vehicleData = dataSnapshot.getValue(VehicleData.class);
//Prints values to console to prove the download is working
System.out.println("getEngineRPM: " + Objects.requireNonNull(vehicleData).getEngineRPM());
System.out.println("prevChildKey: " + prevChildKey);
System.out.println("data.key" + dataSnapshot.getKey());
//Converting value to integer
setData(Integer.parseInt(dataSnapshot.getKey()), vehicleData);
//Will refresh app when the data changes in the database
arrayAdapter.notifyDataSetChanged();
}//End onChildAdded()
//Will run when data within the database is changed/edited
public void onChildChanged(DataSnapshot dataSnapshot, String s)
{
}//End onChildChanged()
//Will run when data within the database is removed
public void onChildRemoved(DataSnapshot dataSnapshot)
{
}//End onChildRemoved()
//Will run when data within the database is moved to different location
public void onChildMoved(DataSnapshot dataSnapshot, String s)
{
}//End onChildMoved()
//Will run when any sort of error occurs
public void onCancelled(DatabaseError databaseError)
{
}//End onCancelled()
});//End addChildEventListener()
}//End DownloadData()
private void setData(int key, VehicleData vehicleData)
{
//Prints to console first
System.out.println("Using key: " + key);
System.out.println("Setting EngineRPM: " + vehicleData.getEngineRPM());
//Adds new entrys to the arrayList and converts the string into a float
engineRPMlist.add(new Entry(key + 2, Float.parseFloat(vehicleData.getEngineRPM())));
//Change the chart when changes occurs
set1.notifyDataSetChanged();
data.notifyDataChanged();
this.chart.notifyDataSetChanged();
//Redisplay chart
chart.invalidate();
}//End setData()
//Using the String to change the values of the XAis
public class MyXAxisValueFormatter implements IAxisValueFormatter
{
private String[] mVals;
private MyXAxisValueFormatter(String[] vals)
{
this.mVals = vals;
}//End MyXAxisValueFormatter()
@Override
public String getFormattedValue(float value, AxisBase axis)
{
return mVals[(int)value];
}//End getFormattedValue()
}//End MyXAxisValueFormatter()
@Override
//Sends log message if action is performed
public void onChartGestureStart(MotionEvent me, ChartTouchListener.ChartGesture lastPerformedGesture)
{
Log.i(TAG, "onChartGestureStart: X:" + me.getX() + "Y:" + me.getY());
}//End()
@Override
//Sends log message if action is performed
public void onChartGestureEnd(MotionEvent me, ChartTouchListener.ChartGesture lastPerformedGesture)
{
Log.i(TAG, "onChartGestureEnd: " + lastPerformedGesture);
}//End()
@Override
//Sends log message if action is performed
public void onChartLongPressed(MotionEvent me)
{
Log.i(TAG, "onChartLongPressed: ");
}//End()
@Override
//Sends log message if action is performed
public void onChartDoubleTapped(MotionEvent me)
{
Log.i(TAG, "onChartDoubleTapped: ");
}//End()
@Override
//Sends log message if action is performed
public void onChartSingleTapped(MotionEvent me)
{
Log.i(TAG, "onChartSingleTapped: ");
}//End()
@Override
public void onChartFling(MotionEvent me1, MotionEvent me2, float velocityX, float velocityY)
{
Log.i(TAG, "onChartFling: veloX: " + velocityX + "veloY" + velocityY);
}//End()
@Override
//Sends log message if action is performed
public void onChartScale(MotionEvent me, float scaleX, float scaleY)
{
Log.i(TAG, "onChartScale: ScaleX: " + scaleX + "ScaleY: " + scaleY);
}//End()
@Override
public void onChartTranslate(MotionEvent me, float dX, float dY)
{
Log.i(TAG, "onChartTranslate: dX" + dX + "dY" + dY);
}//End()
@Override
//Sends log message if action is performed
public void onValueSelected(Entry e, Highlight h)
{
Log.i(TAG, "onValueSelected: " + e.toString());
Toast.makeText(this, "onValueSelected: " + e.toString(), Toast.LENGTH_SHORT).show();
}//End()
@Override
//Sends log message if action is performed
public void onNothingSelected()
{
Log.i(TAG, "onNothingSelected: ");
}//End()
}//End GraphEngineRPM