Initial Commit

Author: Rajeev Kumar Singh

.DS_Store

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+.idea
+*.class
+*.iml

.gitignore

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+.idea
+*.class
+*.iml

Readme.md

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+import java.util.ArrayList;
+import java.util.List;
+
+public class AccessElementsFromArrayListExample {
+    public static void main(String[] args) {
+        List<String> topCompanies = new ArrayList<>();
+
+        // Check if an ArrayList is empty
+        System.out.println("Is the topCompanies list empty? : " + topCompanies.isEmpty());
+
+        topCompanies.add("Google");
+        topCompanies.add("Apple");
+        topCompanies.add("Microsoft");
+        topCompanies.add("Amazon");
+        topCompanies.add("Facebook");
+
+        // Find the size of an ArrayList
+        System.out.println("Here are the top " + topCompanies.size() + " companies in the world");
+        System.out.println(topCompanies);
+
+        // Retrieve the element at a given index
+        String bestCompany = topCompanies.get(0);
+        String secondBestCompany = topCompanies.get(1);
+        String lastCompany = topCompanies.get(topCompanies.size() - 1);
+
+        System.out.println("Best Company: " + bestCompany);
+        System.out.println("Second Best Company: " + secondBestCompany);
+        System.out.println("Last Company in the list: " + lastCompany);
+
+        // Modify the element at a given index
+        topCompanies.set(4, "Walmart");
+        System.out.println("Modified top companies list: " + topCompanies);
+    }
+}

java-arraylist-examples/.gitignore

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+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public class ArrayListCollectionsSortExample {
+    public static void main(String[] args) {
+        List<Integer> numbers = new ArrayList<>();
+        numbers.add(13);
+        numbers.add(7);
+        numbers.add(18);
+        numbers.add(5);
+        numbers.add(2);
+
+        System.out.println("Before : " + numbers);
+
+        // Sorting an ArrayList using Collections.sort() method
+        Collections.sort(numbers);
+
+        System.out.println("After : " + numbers);
+    }
+}

java-arraylist-examples/Readme.md

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+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+public class ArrayListIteratorRemoveExample {
+    public static void main(String[] args) {
+        List<Integer> numbers = new ArrayList<>();
+        numbers.add(13);
+        numbers.add(18);
+        numbers.add(25);
+        numbers.add(40);
+
+        Iterator<Integer> numbersIterator = numbers.iterator();
+        while (numbersIterator.hasNext()) {
+            Integer num = numbersIterator.next();
+            if(num % 2 != 0) {
+                numbersIterator.remove();
+            }
+        }
+
+        System.out.println(numbers);
+    }
+}

java-arraylist-examples/src/AccessElementsFromArrayListExample.java

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+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+
+class Person {
+    private String name;
+    private Integer age;
+
+    public Person(String name, Integer age) {
+        this.name = name;
+        this.age = age;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public Integer getAge() {
+        return age;
+    }
+
+    public void setAge(Integer age) {
+        this.age = age;
+    }
+
+    @Override
+    public String toString() {
+        return "{" +
+                "name='" + name + '\'' +
+                ", age=" + age +
+                '}';
+    }
+}
+
+public class ArrayListObjectSortExample {
+    public static void main(String[] args) {
+        List<Person> people = new ArrayList<>();
+        people.add(new Person("Sachin", 47));
+        people.add(new Person("Chris", 34));
+        people.add(new Person("Rajeev", 25));
+        people.add(new Person("David", 31));
+
+        System.out.println("Person List : " + people);
+
+        // Sort People by their Age
+        people.sort((person1, person2) -> {
+            return person1.getAge() - person2.getAge();
+        });
+
+        // A more concise way of writing the above sorting function
+        people.sort(Comparator.comparingInt(Person::getAge));
+
+        System.out.println("Sorted Person List by Age : " + people);
+
+        // You can also sort using Collections.sort() method by passing the custom Comparator
+        Collections.sort(people, Comparator.comparing(Person::getName));
+        System.out.println("Sorted Person List by Name : " + people);
+    }
+}

java-arraylist-examples/src/ArrayListCollectionsSortExample.java

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+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.List;
+
+public class ArrayListSortExample {
+    public static void main(String[] args) {
+        List<String> names = new ArrayList<>();
+        names.add("Lisa");
+        names.add("Jennifer");
+        names.add("Mark");
+        names.add("David");
+
+        System.out.println("Names : " + names);
+
+        // Sort an ArrayList using its sort() method. You must pass a Comparator to the ArrayList.sort() method.
+        names.sort(new Comparator<String>() {
+            @Override
+            public int compare(String name1, String name2) {
+                return name1.compareTo(name2);
+            }
+        });
+
+        // The above `sort()` method call can also be written simply using lambda expressions
+        names.sort((name1, name2) -> name1.compareTo(name2));
+
+        // Following is an even more concise solution
+        names.sort(Comparator.naturalOrder());
+
+        System.out.println("Sorted Names : " + names);
+    }
+}