Add SalaryHistogram class to categorize and print employee salaries into defined ranges

Author: kumarcodes

src/main/java/com/superthirty/SalaryHistogram.java

@@ -0,0 +1,32 @@
+
+package com.superthirty;
+
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+public class SalaryHistogram {
+    public static void main(String[] args) {
+        List<Employee> employees = EmployeeDTO.getEmployees();
+        //Naive Approach
+        List<Double> empListUnder30K = employees.stream().map(Employee::getSalary).filter(x -> x < 30000).toList();
+        List<Double> empListBW30KAnd60K = employees.stream().map(Employee::getSalary)
+                .filter(x -> x > 30000 && x < 60000).toList();
+        List<Double> empListMoreThan60K = employees.stream().map(Employee::getSalary)
+                .filter(x -> x > 60000).toList();
+        System.out.println(empListUnder30K);
+        System.out.println(empListBW30KAnd60K);
+        System.out.println(empListMoreThan60K);
+        //Pro Approach
+        Map<String, List<Double>> histogram = employees.stream().map(Employee::getSalary).collect(Collectors.groupingBy(
+                salary -> {
+                    if (salary < 30000)
+                        return "Under 30K";
+                    if (salary >= 30000 && salary < 60000)
+                        return "Between 30K and 60K";
+                    return "More than or Equal to 60K";
+
+                }));
+        System.out.println(histogram);
+    }
+}