Example Code for BAEL-1425 (#4394)

* added example code for Java mail

* added examp code for BAEL-1425

* updated example code for BAEL-1425

core-java/pom.xml

@@ -198,6 +198,11 @@
             <artifactId>mail</artifactId>
             <version>${javax.mail.version}</version>
         </dependency>
+        <dependency>
+            <groupId>javax.mail</groupId>
+            <artifactId>mail</artifactId>
+            <version>1.5.0-b01</version>
+        </dependency>
     </dependencies>
 
     <build>

libraries/pom.xml

@@ -698,6 +698,17 @@
             <artifactId>jctools-core</artifactId>
             <version>${jctools.version}</version>
         </dependency>
+
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-math3</artifactId>
+            <version>${common-math3-version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.knowm.xchart</groupId>
+            <artifactId>xchart</artifactId>
+            <version>${xchart-version}</version>
+        </dependency>
     </dependencies>
 
     <repositories>
@@ -910,6 +921,8 @@
         <jets3t-version>0.9.4.0006L</jets3t-version>
         <jctools.version>2.1.2</jctools.version>
         <typesafe-akka.version>2.5.11</typesafe-akka.version>
+        <common-math3-version>3.6.1</common-math3-version>
+        <xchart-version>3.5.2</xchart-version>
     </properties>
 
 </project>

libraries/src/main/java/com/baeldung/commons/math3/Histogram.java

@@ -0,0 +1,90 @@
+package com.baeldung.commons.math3;
+
+import org.apache.commons.math3.stat.Frequency;
+import org.knowm.xchart.CategoryChart;
+import org.knowm.xchart.CategoryChartBuilder;
+import org.knowm.xchart.SwingWrapper;
+import org.knowm.xchart.style.Styler;
+
+import java.util.*;
+
+public class Histogram {
+
+    public Histogram() {
+
+        Map distributionMap = processRawData();
+        List yData = new ArrayList();
+        yData.addAll(distributionMap.values());
+        List xData = Arrays.asList(distributionMap.keySet().toArray());
+
+        CategoryChart chart = buildChart(xData, yData);
+        new SwingWrapper<>(chart).displayChart();
+
+    }
+
+    private CategoryChart buildChart(List xData, List yData) {
+
+        // Create Chart
+        CategoryChart chart = new CategoryChartBuilder().width(800).height(600)
+                .title("Age Distribution")
+                .xAxisTitle("Age Group")
+                .yAxisTitle("Frequency")
+                .build();
+
+        chart.getStyler().setLegendPosition(Styler.LegendPosition.InsideNW);
+        chart.getStyler().setAvailableSpaceFill(0.99);
+        chart.getStyler().setOverlapped(true);
+
+        chart.addSeries("age group", xData, yData);
+
+        return chart;
+    }
+
+    private Map processRawData() {
+
+        List<Integer> datasetList = Arrays.asList(36, 25, 38, 46, 55, 68, 72, 55, 36, 38, 67, 45, 22, 48, 91, 46, 52, 61, 58, 55);
+        Frequency frequency = new Frequency();
+        datasetList.forEach(d -> frequency.addValue(Double.parseDouble(d.toString())));
+
+        int classWidth = 10;
+
+        Map distributionMap = new TreeMap();
+        List processed = new ArrayList();
+        datasetList.forEach(d -> {
+
+            double observation = Double.parseDouble(d.toString());
+
+            if(processed.contains(observation))
+                return;
+
+            long observationFrequency = frequency.getCount(observation);
+            int upperBoundary = (observation > classWidth) ? Math.multiplyExact( (int) Math.ceil(observation / classWidth), classWidth) : classWidth;
+            int lowerBoundary = (upperBoundary > classWidth) ? Math.subtractExact(upperBoundary, classWidth) : 0;
+            String bin = lowerBoundary + "-" + upperBoundary;
+
+            int prevUpperBoundary = lowerBoundary;
+            int prevLowerBoundary = (lowerBoundary > classWidth) ? lowerBoundary - classWidth : 0;
+            String prevBin = prevLowerBoundary + "-" + prevUpperBoundary;
+            if(!distributionMap.containsKey(prevBin))
+                distributionMap.put(prevBin, 0);
+
+            if(!distributionMap.containsKey(bin)) {
+                distributionMap.put(bin, observationFrequency);
+            }
+            else {
+                long oldFrequency = Long.parseLong(distributionMap.get(bin).toString());
+                distributionMap.replace(bin, oldFrequency + observationFrequency);
+            }
+
+            processed.add(observation);
+
+        });
+
+        return distributionMap;
+    }
+
+    public static void main(String[] args) {
+        new Histogram();
+    }
+
+}