Added java stream examples

Java/Java-stream-filter/Example1.java

@@ -0,0 +1,65 @@
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+enum OrderType {
+    ONLINE,
+    OFFLINE
+}
+
+class Order {
+    private String customerName;
+    private OrderType orderType;
+    private float amount;
+
+    Order(OrderType _orderType, float _amount, String _customerName){
+        this.orderType = _orderType;
+        this.amount = _amount;
+        this.customerName = _customerName;
+    }
+
+    public OrderType getOrderType() {
+        return orderType;
+    }
+
+    public float getAmount() {
+        return amount;
+    }
+
+    public String getCustomerName() {
+        return customerName;
+    }
+
+    static void printOrders(List<Order> orderList){
+        orderList.forEach(e -> {
+            System.out.println("Customer Name : "+e.getCustomerName()+", Order type : "+e.getOrderType()+" , Amount : "+e.getAmount());
+        });
+    }
+}
+
+
+public class Example1 {
+
+    public static void main(String[] args) {
+        Order[] orderArray = {new Order(OrderType.OFFLINE, 1000, "Bob"), new Order(OrderType.ONLINE, 500, "Rose"),
+                new Order(OrderType.OFFLINE, 400, "Nancy"), new Order(OrderType.ONLINE, 1500, "Kate")};
+
+        List<Order> orderList = Arrays.asList(orderArray);
+
+        System.out.println("Given Orders : ");
+        Order.printOrders(orderList);
+
+        List<Order> offlineList = orderList.stream()
+                .filter(item -> item.getOrderType().equals(OrderType.OFFLINE))
+                .collect(Collectors.toList());
+
+        System.out.println("Offline order list : ");
+        Order.printOrders(offlineList);
+
+        List<Order> belowThousandList = orderList.stream()
+                .filter(item -> item.getAmount() < 1000)
+                .collect(Collectors.toList());
+        System.out.println("Orders with less than 1000 : ");
+        Order.printOrders(belowThousandList);
+    }
+}

Java/Java-stream-filter/Example2.java

@@ -0,0 +1,50 @@
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+
+class Customer {
+    private String name;
+    private String country;
+
+    Customer(String _name, String _country){
+        this.name = _name;
+        this.country = _country;
+    }
+
+    String getCountry() {
+        return country;
+    }
+
+    private String getName() {
+        return name;
+    }
+
+    static void printCustomerDetail(List<Customer> customerList){
+        customerList.forEach( e -> System.out.println("Customer name : "+e.getName()+" Country : "+e.getCountry()));
+    }
+}
+
+
+public class Example2 {
+
+    public static void main(String[] args) {
+        Map<Integer,Customer> customerMap = new HashMap<>();
+        String country = "UK";
+
+        customerMap.put(1, new Customer("Boris","UK"));
+        customerMap.put(2, new Customer("William","UK"));
+        customerMap.put(3, new Customer("Simon","UK"));
+        customerMap.put(4, new Customer("Paul","Zimbabwe"));
+
+        List<Customer> customerList = customerMap
+                .entrySet()
+                .stream()
+                .filter(x -> x.getValue().getCountry().equals(country))
+                .map(item -> item.getValue())
+                .collect(Collectors.toList());
+
+        Customer.printCustomerDetail(customerList);
+    }
+}

Java/Java-stream-filter/Example3.java

@@ -0,0 +1,50 @@
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.Predicate;
+import java.util.stream.Collectors;
+
+
+class Student {
+    private String name;
+    private int marks;
+
+    Student(String _name, int _marks){
+        this.name = _name;
+        this.marks = _marks;
+    }
+
+    String getName() {
+        return name;
+    }
+
+    int getMarks() {
+        return marks;
+    }
+
+    static void printStudents(List<Student> studentList){
+        studentList.forEach( e -> System.out.println("Student name : "+e.getName()+" Marks : "+e.getMarks()));
+    }
+}
+
+
+public class Example3 {
+
+    public static void main(String[] args) {
+        Student[] studentArray = {new Student("Jacob", 80), new Student("Amanda", 70),
+                new Student("Ashley", 85), new Student("Alexis", 90)};
+        List<Student> studentList = Arrays.asList(studentArray);
+
+        Predicate<Student> studentFilterPredicate = new Predicate<Student>() {
+            @Override
+            public boolean test(Student student) {
+                return student.getName().startsWith("A") && student.getMarks() > 80;
+            }
+        };
+
+        List<Student> studentAList = studentList.stream()
+                .filter(studentFilterPredicate)
+                .collect(Collectors.toList());
+
+        Student.printStudents(studentAList);
+    }
+}