Creating A Java Application With Apache Commons Math In NetBeans

Apache Commons Math gives Java developers a dependable set of tools for statistics, linear algebra, optimisation, probability, and numerical analysis. When the library is combined with NetBeans IDE, you can create, run, debug, and package a small analytical application without assembling every mathematical operation yourself.

This walkthrough builds a simple Java program that calculates descriptive statistics from Australian electricity-usage readings. The same pattern can support forecasting, engineering calculations, school projects, financial modelling, or business reporting for teams in Sydney, Melbourne, Brisbane, and beyond.

NetBeans works well for this task because project configuration, dependency management, source navigation, and debugging are available in one workspace. The example uses Maven, which makes it easier to keep the Commons Math version consistent across a laptop, a CI server, and a developer working remotely in Perth or regional New South Wales.

A numerical library does not remove the need for sound application design. Inputs still need validation, units should be documented, and the program should make clear whether it is using a sample or a population calculation. Those details matter when results inform a household bill, a manufacturing decision, or a report prepared for an Australian customer.

Choose The Project Structure And Dependency

Open NetBeans and select File > New Project, then choose Java with Maven > Java Application. Give the project a practical name such as EnergyStatisticsApp, select a suitable JDK, and allow NetBeans to create the standard src/main/java and src/test/java directories.

Open pom.xml and add Apache Commons Math 3 as a dependency:

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-math3</artifactId>
    <version>3.6.1</version>
</dependency>

Save the file so Maven downloads the JAR and its metadata. In the Projects window, expand Dependencies to check that the library is available. If the dependency does not appear, right-click the project and choose Reload Project, then check the Maven output for proxy, repository, or JDK errors.

Keep the main class small and move reusable calculations into a separate service class. This makes it easier to write tests and keeps the user interface, file import code, and numerical logic from becoming tangled. NetBeans can also help organise imports automatically; the automatic import optimisation feature is useful when Commons Math adds several related types to a class.

Build A Descriptive Statistics Example

Create a package such as au.example.statistics and add a class named EnergySummary. The program can use hourly readings expressed in kilowatt-hours:

package au.example.statistics;

import org.apache.commons.math3.stat.descriptive.DescriptiveStatistics;

public class EnergySummary {

    public static void main(String[] args) {
        double[] readings = {8.4, 7.9, 9.1, 12.6, 10.8, 6.7, 8.8};

        DescriptiveStatistics stats = new DescriptiveStatistics(readings);

        System.out.printf("Mean: %.2f kWh%n", stats.getMean());
        System.out.printf("Median: %.2f kWh%n", stats.getPercentile(50));
        System.out.printf("Minimum: %.2f kWh%n", stats.getMin());
        System.out.printf("Maximum: %.2f kWh%n", stats.getMax());
        System.out.printf("Standard deviation: %.2f kWh%n",
                stats.getStandardDeviation());
    }
}

Right-click the class and select Run File. The output window should display a summary based on the seven readings. A value such as 12.6 could represent a hotter Brisbane day when air-conditioning use rises, while a lower result may reflect mild weather or a household with rooftop solar.

DescriptiveStatistics stores the observations and provides common measures without requiring you to implement sorting, averaging, or variance calculations manually. For a large CSV file, you can add values one at a time with addValue(double) rather than loading the complete dataset into an array.

Extend The Program With Practical Analysis

The library becomes more useful when the application reports information that supports a decision. Add a percentile and a range calculation:

double p90 = stats.getPercentile(90);
double range = stats.getMax() - stats.getMin();

System.out.printf("90th percentile: %.2f kWh%n", p90);
System.out.printf("Range: %.2f kWh%n", range);

The 90th percentile can help estimate a high-but-usual usage level for a property manager or energy adviser. If the application later calculates costs, keep the tariff in Australian dollars and store the rate separately from the readings. A retailer may charge a daily supply fee, time-of-use rates, or a feed-in tariff, so one hard-coded price can produce a misleading estimate.

For matrix calculations, import classes from org.apache.commons.math3.linear. For example, Array2DRowRealMatrix can represent a table of measurements, while LUDecomposition can solve a system of linear equations. Probability distributions, regression models, and optimisation classes follow the same Maven-based setup.

Numerical code is also a good candidate for a service layer in a larger Java application. If the results are produced by an enterprise component, review how a stateful session bean maintains conversational data between calls. That approach may suit a multi-step analysis workflow, although stateless processing is often simpler for independent calculations.

Test Results And Diagnose Common Errors

Create a JUnit test under src/test/java to verify known values. A basic test can construct DescriptiveStatistics, add a few readings, and use assertions for the mean and minimum. Testing small datasets makes mistakes visible before a program processes thousands of records from a smart meter or a business export.

Pay attention to empty input, NaN, infinite values, and unexpected negative readings. A validation method should reject invalid measurements or record them clearly rather than allowing them to distort the report. Also document whether standard deviation uses the sample convention, since that distinction can matter in scientific, educational, and compliance-related work.

If NetBeans reports that a Commons Math class cannot be found, inspect pom.xml, confirm that Maven is online, and verify the dependency under the project tree. A project using a different JDK may also expose source or target compatibility problems. Clean and build the project after changing the JDK or dependency version.

When this logic is called from an enterprise application, understand the lifecycle and invocation path before adding state. A session bean call can be appropriate when a calculation spans several user actions, but a plain Java service is usually easier to test for a single batch operation.

Recommendations For A Reliable NetBeans Application

Keep the numerical core independent from NetBeans-specific code. NetBeans is the development environment; Commons Math performs the calculations, and your own classes should define validation, business rules, and output formatting.

  • Use Maven so every developer receives the same Commons Math dependency.
  • Store units beside field names, such as dailyUsageKwh, rather than using vague variables like value.
  • Validate blank files, malformed decimals, negative readings, and missing tariff data.
  • Add JUnit tests for empty, typical, and unusually large datasets.
  • Format currency with an Australian locale when presenting dollar values to users.
  • Record the library version and JDK version in project documentation.

A clean separation makes the application easier to move from a NetBeans desktop project into a command-line tool, web service, or scheduled reporting job. It also leaves room to add CSV import, charts, regression, or optimisation later without rewriting the initial statistics code.