map-reduce

Author: basahota

map_reduce/Employee.java

@@ -0,0 +1,52 @@
+package com.javatechie.map_reduce;
+
+public class Employee {
+    private int id;
+    private String name;
+    private String grade;
+    private double salary;
+
+    public Employee() {
+    }
+
+    public Employee(int id, String name, String grade, double salary) {
+        this.id = id;
+        this.name = name;
+        this.grade = grade;
+        this.salary = salary;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getGrade() {
+        return grade;
+    }
+
+    public void setGrade(String grade) {
+        this.grade = grade;
+    }
+
+    public double getSalary() {
+        return salary;
+    }
+
+    public void setSalary(double salary) {
+        this.salary = salary;
+    }
+
+
+}

map_reduce/EmployeeDatabase.java

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+package com.javatechie.map_reduce;
+
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class EmployeeDatabase {
+
+
+    public static List<Employee> getEmployees(){
+      return  Stream.of(new Employee(101,"john","A",60000),
+              new Employee(109,"peter","B",30000),
+              new Employee(102,"mak","A",80000),
+              new Employee(103,"kim","A",90000),
+              new Employee(104,"json","C",15000))
+              .collect(Collectors.toList());
+    }
+}

map_reduce/MapReduceExample.java

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+package com.javatechie.map_reduce;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+
+public class MapReduceExample {
+
+    public static void main(String[] args) {
+
+        List<Integer> numbers = Arrays.asList(3, 7, 8, 1, 5, 9);
+
+        List<String> words = Arrays.asList("corejava", "spring", "hibernate");
+
+        int sum = 0;
+        for (int no : numbers) {
+            sum = sum + no;
+        }
+        System.out.println(sum);
+
+        int sum1 = numbers.stream().mapToInt(i -> i).sum();
+        System.out.println(sum1);
+
+        Integer reduceSum = numbers.stream().reduce(0, (a, b) -> a + b);
+        System.out.println(reduceSum);
+
+        Optional<Integer> reduceSumWithMethodReference = numbers.stream().reduce(Integer::sum);
+        System.out.println(reduceSumWithMethodReference.get());
+
+        Integer mulResult = numbers.stream().reduce(1, (a, b) -> a * b);
+        System.out.println(mulResult);
+
+        Integer maxvalue = numbers.stream().reduce(0, (a, b) -> a > b ? a : b);
+        System.out.println(maxvalue);
+
+        Integer maxvalueWithMethodReference = numbers.stream().reduce(Integer::max).get();
+        System.out.println(maxvalueWithMethodReference);
+
+
+        String longestString = words.stream()
+                .reduce((word1, word2) -> word1.length() > word2.length() ? word1 : word2)
+                .get();
+        System.out.println(longestString);
+
+        //get employee whose grade A
+        //get salary
+        double avgSalary = EmployeeDatabase.getEmployees().stream()
+                .filter(employee -> employee.getGrade().equalsIgnoreCase("A"))
+                .map(employee -> employee.getSalary())
+                .mapToDouble(i -> i)
+                .average().getAsDouble();
+
+        System.out.println(avgSalary);
+
+        double sumSalary = EmployeeDatabase.getEmployees().stream()
+                .filter(employee -> employee.getGrade().equalsIgnoreCase("A"))
+                .map(employee -> employee.getSalary())
+                .mapToDouble(i -> i)
+                .sum();
+        System.out.println(sumSalary);
+    }
+
+
+}