How to automate the initialization of variables

[zakhussain299]

A part of my code required me to initialize n number of variables. How can it be done. For example

......
.......
XYDataset[] data;
for(int i<0;i<size;i++)
{
data[i]="data"+i;
}
for(int i=0;i<size;i++)
{
XYDataset data[i]=new XYDataset();
}
.......

I think you might understand from the example above what I want to do....I just want to have n number of instance variables of the class XYDataset initialized, so that I can then use it my code....How can I do that....I would really appreciate any help....

[Norm]

I just want to have n number of instance variables of the class XYDataset initialized

I would use code like you have posted. I would add an assignment to give data a value:
data = new XYData[n]; // Set data to an array of n slots
What are you asking to be done differently?

A problem is you are redefining data in the loop:
XYDataset data[i]=new XYDataset();

A new version:

         String[] data = new String[5];    // Create an array with 5 elements
         for(int i= 0; i<data.length; i++)         {
           data[i]="data"+i;         // fill the array
         }

         for(int i=0; i<data.length; i++)           {
            data[i]=new String();    // fill the array again
         }

[zakhussain299]

I would use code like you have posted. I would add an assignment to give data a value:
data = new XYData[n]; // Set data to an array of n slots
What are you asking to be done differently?

A problem is you are redefining data in the loop:
XYDataset data[i]=new XYDataset();

A new version:

         String[] data = new String[5];    // Create an array with 5 elements
         for(int i= 0; i<data.length; i++)         {
           data[i]="data"+i;         // fill the array
         }

         for(int i=0; i<data.length; i++)           {
            data[i]=new String();    // fill the array again
         }

Let me post the entire program:



public class CombinedXYPlotDemo1 extends ApplicationFrame {

/**
* Constructs a new demonstration application.
*
* @param title the frame title.
*/
public CombinedXYPlotDemo1(final String title) {

super(title);
final JFreeChart chart = createCombinedChart();
final ChartPanel panel = new ChartPanel(chart, true, true, true, false, true);
panel.setPreferredSize(new java.awt.Dimension(500, 270));
setContentPane(panel);

}

/**
* Creates a combined chart.
*
* @return the combined chart.
*/
private JFreeChart createCombinedChart() {

// create subplot 1...
final XYDataset data1 = createDataset1();
final XYItemRenderer renderer1 = new StandardXYItemRenderer();
final NumberAxis rangeAxis1 = new NumberAxis("Range 1");
final XYPlot subplot1 = new XYPlot(data1, null, rangeAxis1, renderer1);
subplot1.setRangeAxisLocation(AxisLocation.BOTTOM_OR_LEFT);

final XYTextAnnotation annotation = new XYTextAnnotation("Hello!", 50.0, 10000.0);
annotation.setFont(new Font("SansSerif", Font.PLAIN, 9));
annotation.setRotationAngle(Math.PI / 4.0);
subplot1.addAnnotation(annotation);

// create subplot 2...
final XYDataset data2 = createDataset2();
final XYItemRenderer renderer2 = new StandardXYItemRenderer();
final NumberAxis rangeAxis2 = new NumberAxis("Range 2");
rangeAxis2.setAutoRangeIncludesZero(false);
final XYPlot subplot2 = new XYPlot(data2, null, rangeAxis2, renderer2);
subplot2.setRangeAxisLocation(AxisLocation.TOP_OR_LEFT);

// parent plot...
final CombinedDomainXYPlot plot = new CombinedDomainXYPlot(new NumberAxis("Domain"));
plot.setGap(10.0);

// add the subplots...
plot.add(subplot1, 1);
plot.add(subplot2, 1);
plot.setOrientation(PlotOrientation.VERTICAL);

// return a new chart containing the overlaid plot...
return new JFreeChart("CombinedDomainXYPlot Demo",
JFreeChart.DEFAULT_TITLE_FONT, plot, true);

}

/**
* Creates a sample dataset.
*
* @return Series 1.
*/
private XYDataset createDataset1() {

// create dataset 1...
final XYSeries series1 = new XYSeries("Series 1");
series1.add(10.0, 12353.3);
series1.add(20.0, 13734.4);
series1.add(30.0, 14525.3);
series1.add(40.0, 13984.3);
series1.add(50.0, 12999.4);
series1.add(60.0, 14274.3);
series1.add(70.0, 15943.5);
series1.add(80.0, 14845.3);
series1.add(90.0, 14645.4);
series1.add(100.0, 16234.6);
series1.add(110.0, 17232.3);
series1.add(120.0, 14232.2);
series1.add(130.0, 13102.2);
series1.add(140.0, 14230.2);
series1.add(150.0, 11235.2);

final XYSeries series2 = new XYSeries("Series 2");
series2.add(10.0, 15000.3);
series2.add(20.0, 11000.4);
series2.add(30.0, 17000.3);
series2.add(40.0, 15000.3);
series2.add(50.0, 14000.4);
series2.add(60.0, 12000.3);
series2.add(70.0, 11000.5);
series2.add(80.0, 12000.3);
series2.add(90.0, 13000.4);
series2.add(100.0, 12000.6);
series2.add(110.0, 13000.3);
series2.add(120.0, 17000.2);
series2.add(130.0, 18000.2);
series2.add(140.0, 16000.2);
series2.add(150.0, 17000.2);

final XYSeriesCollection collection = new XYSeriesCollection();
collection.addSeries(series1);
collection.addSeries(series2);
return collection;

}

/**
* Creates a sample dataset.
*
* @return Series 2.
*/
private XYDataset createDataset2() {

// create dataset 2...
final XYSeries series2 = new XYSeries("Series 3");

series2.add(10.0, 16853.2);
series2.add(20.0, 19642.3);
series2.add(30.0, 18253.5);
series2.add(40.0, 15352.3);
series2.add(50.0, 13532.0);
series2.add(100.0, 12635.3);
series2.add(110.0, 13998.2);
series2.add(120.0, 11943.2);
series2.add(130.0, 16943.9);
series2.add(140.0, 17843.2);
series2.add(150.0, 16495.3);
series2.add(160.0, 17943.6);
series2.add(170.0, 18500.7);
series2.add(180.0, 19595.9);

return new XYSeriesCollection(series2);

}

// ****************************************************************************
// * JFREECHART DEVELOPER GUIDE *
// * The JFreeChart Developer Guide, written by David Gilbert, is available *
// * to purchase from Object Refinery Limited: *
// * *
// * http://www.object-refinery.com/jfreechart/guide.html *
// * *
// * Sales are used to provide funding for the JFreeChart project - please *
// * support us so that we can continue developing free software. *
// ****************************************************************************

/**
* Starting point for the demonstration application.
*
* @param args ignored.
*/
public static void main(final String[] args) {

final CombinedXYPlotDemo1 demo = new CombinedXYPlotDemo1("CombinedDomainXYPlot Demo");
demo.pack();
RefineryUtilities.centerFrameOnScreen(demo);
demo.setVisible(true);

}

}





If u look at createDataset1(), In this as you can see there are 2 series, series1 and series2, but in my program the number of series depend on a random number, so in that case how can I automate the process, suppose if the random number is 4, then I want the initialization to be for series1,series2,series3 and series4, so that I can then fill the respective series with the dataset values to plot the graph.

[zakhussain299]

Let me post the entire code:


public class CombinedXYPlotDemo4 extends ApplicationFrame {

/**
* Constructs a new demonstration application.
*
* @param title the frame title.
*/
public CombinedXYPlotDemo4(final String title) {

super(title);
final JFreeChart chart = createCombinedChart();
final ChartPanel panel = new ChartPanel(chart, true, true, true, false, true);
panel.setPreferredSize(new java.awt.Dimension(500, 270));
setContentPane(panel);

}

/**
* Creates a combined chart.
*
* @return The combined chart.
*/
private JFreeChart createCombinedChart() {

// create subplot 1...
final XYDataset data1 = createDataset1();
final XYItemRenderer renderer1 = new StandardXYItemRenderer();
final NumberAxis rangeAxis1 = new NumberAxis("Range 1");
final XYPlot subplot1 = new XYPlot(data1, null, rangeAxis1, renderer1);
subplot1.setRangeAxisLocation(AxisLocation.BOTTOM_OR_LEFT);

// add secondary axis
subplot1.setDataset(1, createDataset2());
final NumberAxis axis2 = new NumberAxis("Range Axis 2");
axis2.setAutoRangeIncludesZero(false);
subplot1.setRangeAxis(1, axis2);
subplot1.setRangeAxisLocation(1, AxisLocation.BOTTOM_OR_RIGHT);
subplot1.setRenderer(1, new StandardXYItemRenderer());
subplot1.mapDatasetToRangeAxis(1, 1);

final XYTextAnnotation annotation = new XYTextAnnotation("Hello!", 50.0, 10000.0);
annotation.setFont(new Font("SansSerif", Font.PLAIN, 9));
annotation.setRotationAngle(Math.PI / 4.0);
subplot1.addAnnotation(annotation);

// create subplot 2...
final XYDataset data2 = createDataset2();
final XYItemRenderer renderer2 = new StandardXYItemRenderer();
final NumberAxis rangeAxis2 = new NumberAxis("Range 2");
rangeAxis2.setAutoRangeIncludesZero(false);
final XYPlot subplot2 = new XYPlot(data2, null, rangeAxis2, renderer2);
subplot2.setRangeAxisLocation(AxisLocation.TOP_OR_LEFT);

// parent plot...
final CombinedDomainXYPlot plot = new CombinedDomainXYPlot(new NumberAxis("Domain"));
plot.setGap(10.0);

// add the subplots...
plot.add(subplot1, 1);
plot.add(subplot2, 1);
plot.setOrientation(PlotOrientation.VERTICAL);

// return a new chart containing the overlaid plot...
return new JFreeChart("CombinedDomainXYPlot Demo",
JFreeChart.DEFAULT_TITLE_FONT, plot, true);

}

/**
* Creates a sample dataset.
*
* @return Series 1.
*/
private XYDataset createDataset1() {

// create dataset 1...
final XYSeries series1 = new XYSeries("Series 1a");
series1.add(10.0, 12353.3);
series1.add(20.0, 13734.4);
series1.add(30.0, 14525.3);
series1.add(40.0, 13984.3);
series1.add(50.0, 12999.4);
series1.add(60.0, 14274.3);
series1.add(70.0, 15943.5);
series1.add(80.0, 14845.3);
series1.add(90.0, 14645.4);
series1.add(100.0, 16234.6);
series1.add(110.0, 17232.3);
series1.add(120.0, 14232.2);
series1.add(130.0, 13102.2);
series1.add(140.0, 14230.2);
series1.add(150.0, 11235.2);

final XYSeries series1b = new XYSeries("Series 1b");
series1b.add(10.0, 15000.3);
series1b.add(20.0, 11000.4);
series1b.add(30.0, 17000.3);
series1b.add(40.0, 15000.3);
series1b.add(50.0, 14000.4);
series1b.add(60.0, 12000.3);
series1b.add(70.0, 11000.5);
series1b.add(80.0, 12000.3);
series1b.add(90.0, 13000.4);
series1b.add(100.0, 12000.6);
series1b.add(110.0, 13000.3);
series1b.add(120.0, 17000.2);
series1b.add(130.0, 18000.2);
series1b.add(140.0, 16000.2);
series1b.add(150.0, 17000.2);

final XYSeriesCollection collection = new XYSeriesCollection();
collection.addSeries(series1);
collection.addSeries(series1b);
return collection;

}

/**
* Creates a sample dataset.
*
* @return A sample dataset.
*/
private XYDataset createDataset2() {

// create dataset 2...
final XYSeries series2 = new XYSeries("Series 2");

series2.add(10.0, 16853.2);
series2.add(20.0, 19642.3);
series2.add(30.0, 18253.5);
series2.add(40.0, 15352.3);
series2.add(50.0, 13532.0);
series2.add(100.0, 12635.3);
series2.add(110.0, 13998.2);
series2.add(120.0, 11943.2);
series2.add(130.0, 16943.9);
series2.add(140.0, 17843.2);
series2.add(150.0, 16495.3);
series2.add(160.0, 17943.6);
series2.add(170.0, 18500.7);
series2.add(180.0, 19595.9);

return new XYSeriesCollection(series2);

}

// ****************************************************************************
// * JFREECHART DEVELOPER GUIDE *
// * The JFreeChart Developer Guide, written by David Gilbert, is available *
// * to purchase from Object Refinery Limited: *
// * *
// * http://www.object-refinery.com/jfreechart/guide.html *
// * *
// * Sales are used to provide funding for the JFreeChart project - please *
// * support us so that we can continue developing free software. *
// ****************************************************************************

/**
* Starting point for the demonstration application.
*
* @param args ignored.
*/
public static void main(final String[] args) {

final CombinedXYPlotDemo4 demo = new CombinedXYPlotDemo4("CombinedDomainXYPlot Demo");
demo.pack();
RefineryUtilities.centerFrameOnScreen(demo);
demo.setVisible(true);

}

}




As you can see in createDataset1() and createDataset2(), they have series1 and series2 which are somewhat hard coded into the code. The output of this program will plot a graph. But for my program I would have random number of series , in order to plot the graph for random number of series, I would have to somehow automate the initialization of the instance variable "series". For example, suppose the random number is 5, then I would have series0,series1,series2,series3 and series4 initialized. But I am not sure how I can somehow automate the initialization of "series" in createDataset1() and createDataset2() for random number of series.

[Norm]

automate the initialization of the instance variable "series".

Variable names are defined at compile time.
You can create new "named" variables by using a Map. The Map's key can be treated as the variable name.

String name = "series";
for(int i=0; i < nbrOfSeries; i++) {
  name += i;  // build new name for this one
  XYSeries aSeries = new XYSeries("Series " + i);  // create the instance
  aSeries.add(....);   // fill with data
   ...
  theMap.put(name, aSeries);  // Save the reference
}

[nuzzle]

A part of my code required me to initialize n number of variables. How can it be done.

You can use an initializer. It looks like this,

public class A {
   private int[] a;  // array of integers

   { // an initializer (runs before any constructor)
        // here you can do complex intializations of variables involving 
        // code such as assignments and for-loops:
      a = new int[10];
      for (int i=0; i<a.length(); i++) {
         a[i] = i;
      }
   }

}