ArrayListFun.java

package arraylist;
import java.util.ArrayList;
public class ArrayListFun {

	public static void main(String[] args) {
		// creating ArrayList(AL) of name arr
		
		ArrayList<Integer> arr1=new ArrayList<>();

		//1. add(value) - This will keep on adding value in last of array list.
			arr1.add(2);
			arr1.add(7);
			arr1.add(3);
			arr1.add(1);
			arr1.add(7);
			arr1.add(5);
			System.out.println(arr1); //[2, 7, 3, 1, 7, 5]
		
			
		//2. size() - return no. of elements added in AL
			System.out.println(arr1.size());// 6
			
			
		//3. get(index) - return value at particular index
			System.out.println(arr1.get(2));// 3
			
		
		//4. set(index,value) - change value at particular index
			arr1.set(2, 8);
			System.out.println(arr1);// [2, 7, 8, 1, 7, 5]
			
			
			
		//5. indexOf(value) - return first occurrence index of the particular value if present, else return -1
			System.out.println(arr1.indexOf(7)); // 1
			System.out.println(arr1.indexOf(9)); // -1
			
			
		//6. lastIndexOf(value) - return last occurrence index of the particular value if present, else return -1
			System.out.println(arr1.lastIndexOf(7)); // 4
			System.out.println(arr1.lastIndexOf(9)); // -1
			
			
		//7. remove(index) - remove value at particular index and return the removed value
			System.out.println(arr1.remove(2)); // 8
			System.out.println(arr1); // [2, 7, 1, 7, 5]
			
			
			
		//8. add(index,value) - add value at particular index. NOTE: Index should lie in range [0 to arr.size()] 	
			System.out.println(arr1); // before : [2, 7, 1, 7, 5]
			arr1.add(2,3);
			System.out.println(arr1); // after :  [2, 7, 3, 1, 7, 5]
			
			
		//9. addAll(AL) -  appends arr1 into new AL and returns true if successfully appended
			ArrayList<Integer> arr2=new ArrayList<>();
			arr2.add(777);
			arr2.add(888);
			arr2.add(999);
			
			System.out.println(arr1); //[2, 7, 3, 1, 7, 5]
			System.out.println(arr2); // Before : [777, 888, 999]
			
			System.out.println(arr2.addAll(arr1)); // true
			
			System.out.println(arr2); // After: [777, 888, 999, 2, 7, 3, 1, 7, 5]
			
			
			
		//10. addAll(index,AL) - appends arr1 into new AL at particular index and returns true if successfully appended
			ArrayList<Integer> arr3=new ArrayList<>();
			arr3.add(444);
			arr3.add(555);
			arr3.add(666);
			
			System.out.println(arr1); // [2, 7, 3, 1, 7, 5]
			System.out.println(arr3); // Before : [444, 555, 666]
			
			System.out.println(arr3.addAll(2,arr1)); // true
			
			System.out.println(arr3); // After: [444, 555, 2, 7, 3, 1, 7, 5, 666]
		
			
		
		//11. for loop iteration in ArrayList
			for(int i=0;i<arr1.size();i++) {
				System.out.print(arr1.get(i)+" "); // 2 7 3 1 7 5
			}
			System.out.println(); // new line
			//for each loop
			for(int val: arr1) {
				System.out.print(val+" "); // 2 7 3 1 7 5
			}
			System.out.println(); // new line
			
		//12. clear() - remove all elements from AL	
				arr1.clear();
				arr2.clear();
				arr3.clear();
				System.out.println(arr1); // []
				System.out.println(arr2); // []
				System.out.println(arr3); // []
		
		
		// 13. Intialization of new ArrayList with defaultValues.
		ArrayList<Long> arr4=new ArrayList<>(Arrays.asList(3l, 4l, 1l, 9l, 56l, 7l, 9l, 12l));

		//14. Making 2d ArrayList
		ArrayList<ArrayList<Integer>> ans=new ArrayList<>();
		ans.add(new ArrayList<>());
		ans.get(0).add(1);
		ans.get(0).add(2);
		ans.get(0).add(3);
		// [[1,2,3]]
		ans.add(new ArrayList<>()); // [[1,2,3],[]]
		ans.get(1).add(5);
		ans.get(1).add(6);
		ans.get(0).add(4);
		// [[1,2,3,4][5,6]]
	}

}