JavaFX How can I make a line chart out of an observable list? - database

Question

I have been playing around with the line chart tutorial here: http://docs.oracle.com/javase/8/javafx/user-interface-tutorial/line-chart.htm#CIHGBCFI
I want to extend the tutorial and attempt to build a line chart out of data from a database, instead of setting data like this:
series.getData().add(new XYChart.Data(1, 23));
series.getData().add(new XYChart.Data(2, 14));
What I have to import data from database:
public ObservableList<Items> loadChart() {
try {
Statement stmt = connection.createStatement();
ResultSet rs = stmt.executeQuery("SELECT cost, date FROM Items ORDER BY date ASC");
ObservableList<Items> data = FXCollections.observableArrayList();
while(rs.next()){
Items items = new Items();
items.setCost(rs.getInt(1));
items.setDate(rs.getString(2));
data.add(items);
}
return data;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
I want to plot cost and date against in a line chart... Yet don't know how to do so (based on observable list and the tutorial).

Answer 1

If you are using that sample, your code should look something like this.
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.chart.LineChart;
import javafx.scene.chart.NumberAxis;
import javafx.scene.chart.XYChart;
import javafx.stage.Stage;
public class LineChartSample extends Application {
#Override public void start(Stage stage) {
stage.setTitle("Line Chart Sample");
//defining the axes
final NumberAxis xAxis = new NumberAxis();
final NumberAxis yAxis = new NumberAxis();
xAxis.setLabel("Number of Month");
//creating the chart
final LineChart<Number,Number> lineChart =
new LineChart<Number,Number>(xAxis,yAxis);
lineChart.setTitle("Stock Monitoring, 2010");
//defining a series
XYChart.Series series = new XYChart.Series();
series.setName("My portfolio");
//populating the series with data
try
{
Connection connection = DriverManager.getConnection("...");//You can use try with resources. Establish a Connection
Statement stmt = connection.createStatement();//Create Statement
ResultSet rs = stmt.executeQuery("SELECT cost, date FROM Items ORDER BY date ASC");//Query DB and get results.
//Iterate through results.
while(rs.next())
{
series.getData().add(new XYChart.Data(rs.getInt(1), Integer.parseInt(rs.getString(2))));//Add data to Chart. Changed the second input to Integer due to LineChart<Number,Number>. This should work, though I haven't tested it.
}
}
catch (SQLException ex) {
Logger.getLogger(LineChartSample.class.getName()).log(Level.SEVERE, null, ex);
}
Scene scene = new Scene(lineChart,800,600);
lineChart.getData().add(series);
stage.setScene(scene);
stage.show();
}
public static void main(String[] args) {
launch(args);
}
}
UPDATE BELOW
You can try something like this if you want to have a database handler class.
DBHandler Class
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.scene.chart.XYChart;
/**
*
* #author blj0011
*/
public class DBHandler
{
List<List<Integer>> dataHolder;
//There is probably a better way to structure this DBHandler Class
public DBHandler()
{
dataHolder = new ArrayList();
try
{
Connection connection = DriverManager.getConnection("...");//You can use try with resources. Establish a Connection
Statement stmt = connection.createStatement();//Create Statement
ResultSet rs = stmt.executeQuery("SELECT cost, date FROM Items ORDER BY date ASC");//Query DB and get results.
//Iterate through results.
while(rs.next())
{
List<Integer> tempDataHolder = new ArrayList();
tempDataHolder.add(rs.getInt(1));
tempDataHolder.add(Integer.parseInt(rs.getString(2)));
dataHolder.add(tempDataHolder);
}
}
catch (SQLException ex) {
Logger.getLogger(DBHandler.class.getName()).log(Level.SEVERE, null, ex);
}
}
public List<List<Integer>> getDataHolder()
{
return dataHolder;
}
}
Main Class
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.chart.LineChart;
import javafx.scene.chart.NumberAxis;
import javafx.scene.chart.XYChart;
import javafx.stage.Stage;
public class LineChartSample extends Application {
#Override public void start(Stage stage) {
stage.setTitle("Line Chart Sample");
//defining the axes
final NumberAxis xAxis = new NumberAxis();
final NumberAxis yAxis = new NumberAxis();
xAxis.setLabel("Number of Month");
//creating the chart
final LineChart<Number,Number> lineChart =
new LineChart<Number,Number>(xAxis,yAxis);
lineChart.setTitle("Stock Monitoring, 2010");
//defining a series
XYChart.Series series = new XYChart.Series();
series.setName("My portfolio");
//populating the series with data
DBHandler dbHandler = new DBHandler();
List<List<Integer>> dataHolder = dbHandler.getDataHolder();
for(int i = 0; i < dataHolder.size(); i++)
{
series.getData().add(new XYChart.Data(dataHolder.get(i).get(0), dataHolder.get(i).get(1)));
}
Scene scene = new Scene(lineChart,800,600);
lineChart.getData().add(series);
stage.setScene(scene);
stage.show();
}
public static void main(String[] args) {
launch(args);
}
}