Difference between Iterable and Iterator

Add examples of the Iterable and the Iterator usage.

core-java-modules/core-java-collections-2/src/main/java/com/baeldung/collections/iterable/IterableExample.java

@@ -0,0 +1,48 @@
+package com.baeldung.collections.iterable;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+class IterableExample {
+
+    public static void iterateUsingIterator() {
+        List<Integer> numbers = getNumbers();
+
+        Iterator<Integer> iterator = numbers.iterator();
+        while (iterator.hasNext()) {
+            System.out.println(iterator.next());
+        }
+    }
+
+    public static void removeElementsUsingIterator() {
+        List<Integer> numbers = getNumbers();
+
+        Iterator<Integer> iterator = numbers.iterator();
+        while (iterator.hasNext()) {
+            iterator.remove();
+        }
+    }
+
+    public static void iterateUsingEnhancedForLoop() {
+        List<Integer> numbers = getNumbers();
+
+        for (Integer number : numbers) {
+            System.out.println(number);
+        }
+    }
+
+    public static void iterateUsingForEachLoop() {
+        List<Integer> numbers = getNumbers();
+        numbers.forEach(System.out::println);
+    }
+
+    private static List<Integer> getNumbers() {
+        List<Integer> numbers = new ArrayList<>();
+        numbers.add(10);
+        numbers.add(20);
+        numbers.add(30);
+        numbers.add(40);
+        return numbers;
+    }
+}

core-java-modules/core-java-collections-2/src/main/java/com/baeldung/collections/iterable/Product.java

@@ -0,0 +1,28 @@
+package com.baeldung.collections.iterable;
+
+class Product {
+
+    private String name;
+    private double price;
+
+    public Product(String code, double price) {
+        this.name = code;
+        this.price = price;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public double getPrice() {
+        return price;
+    }
+
+    public void setPrice(double price) {
+        this.price = price;
+    }
+}

core-java-modules/core-java-collections-2/src/main/java/com/baeldung/collections/iterable/ProductIterable.java

@@ -0,0 +1,18 @@
+package com.baeldung.collections.iterable;
+
+import java.util.Iterator;
+import java.util.List;
+
+class ProductIterable implements Iterable<Product> {
+
+    List<Product> productList;
+
+    public ProductIterable(List<Product> productList) {
+        this.productList = productList;
+    }
+
+    @Override
+    public Iterator<Product> iterator() {
+        return productList.iterator();
+    }
+}

core-java-modules/core-java-collections-2/src/main/java/com/baeldung/collections/iterable/ProductIterableClient.java

@@ -0,0 +1,17 @@
+package com.baeldung.collections.iterable;
+
+import java.util.Arrays;
+import java.util.List;
+
+class ProductIterableClient {
+
+    public static void main(String[] args) {
+        List<Product> products = Arrays.asList(new Product("Salad", 45), new Product("Tuna", 42), new Product("Eggplant", 65), new Product("Bread", 22), new Product("Banana", 29));
+
+        ProductIterable iterable = new ProductIterable(products);
+
+        for (Product product : iterable) {
+            System.out.println(product.getName());
+        }
+    }
+}

core-java-modules/core-java-collections-2/src/main/java/com/baeldung/collections/iterator/CustomIterator.java

@@ -0,0 +1,8 @@
+package com.baeldung.collections.iterator;
+
+interface CustomIterator<T> {
+
+    boolean hasNext();
+
+    T next();
+}

core-java-modules/core-java-collections-2/src/main/java/com/baeldung/collections/iterator/CustomIteratorClient.java

@@ -0,0 +1,12 @@
+package com.baeldung.collections.iterator;
+
+class CustomIteratorClient {
+
+    public static void main(String[] args) {
+        CustomIterator<Integer> iterator = Numbers.iterator();
+
+        while (iterator.hasNext()) {
+            System.out.println(iterator.next());
+        }
+    }
+}

core-java-modules/core-java-collections-2/src/main/java/com/baeldung/collections/iterator/Numbers.java

@@ -0,0 +1,51 @@
+package com.baeldung.collections.iterator;
+
+import java.util.Arrays;
+import java.util.List;
+
+class Numbers {
+
+    private static final List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
+
+    private Numbers() {
+    }
+
+    public static CustomIterator<Integer> iterator() {
+        return new PrimeIterator();
+    }
+
+    private static class PrimeIterator implements CustomIterator<Integer> {
+
+        private int currentPosition;
+
+        private static boolean isPrime(int number) {
+            for (int i = 2; i <= number / 2; ++i) {
+                if (number % i == 0) {
+                    return false;
+                }
+            }
+            return true;
+        }
+
+        @Override
+        public Integer next() {
+            return numbers.get(currentPosition++);
+        }
+
+        @Override
+        public boolean hasNext() {
+            if (currentPosition > numbers.size()) {
+                return false;
+            }
+
+            for (int i = currentPosition; i < numbers.size(); i++) {
+                if (isPrime(numbers.get(i))) {
+                    currentPosition = i;
+                    return true;
+                }
+            }
+
+            return false;
+        }
+    }
+}