All about ArrayList – Android.

package com.coderzheaven.arraylistcomplete;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Vector;

import android.app.Activity;
import android.os.Bundle;

public class MainActivity extends Activity {

	@SuppressWarnings("unchecked")
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

		ArrayList<String> al = new ArrayList<String>();

		System.out.println("Initial size of al: " + al.size());

		al.add("C");
		al.add("A");
		al.add("E");
		al.add("B");
		al.add("D");
		al.add("F");
		al.add(1, "A2");

		System.out.println("Size of al after additions: " + al.size());

		System.out.println("Contents of al: " + al);

		al.remove("F");
		al.remove(2);

		System.out.println("Size of al after deletions: " + al.size());
		System.out.println("Contents of al: " + al);

		// *********************************************************//

		List<String> list = new ArrayList<String>();
		list.add("A");
		list.add("B");
		list.add("C");
		List<String> list2 = new ArrayList<String>();
		list2.add("X");
		list2.add("Y");
		list2.add("Z");
		list.addAll(list2);
		list.addAll(1, list2);

		System.out.println(list);

		// **********************************************************//

		ArrayList<String> arrayList = new ArrayList<String>();
		arrayList.add("1");
		arrayList.add("2");
		arrayList.add("3");

		Vector<String> v = new Vector<String>();
		v.add("4");
		v.add("5");

		// insert all elements of Vector to ArrayList at index 1
		arrayList.addAll(1, v);

		for (String str : arrayList)
			System.out.println(str);

		list.clear();

		System.out.println("After Clearing");

		for (String str : arrayList)
			System.out.println(str);

		// ****************************************************************//

		ArrayList myList = new ArrayList(5);
		for (int j = 0; j < 5; j++) {
			myList.add(new Integer(j));
		}
		System.out.println("List contains " + myList.size() + " elements");

		Integer int2 = new Integer(2);
		System.out
				.println("List contains Integer(2): " + myList.contains(int2));
		System.out.println("Integer(2) is at index " + myList.indexOf(int2));

		myList.set(2, new Integer(99));
		System.out.println("Get element at index 2: " + myList.get(2));

		myList.ensureCapacity(15);

		for (int k = myList.size(); k < 25; k++) {
			myList.add(k, new Integer(k));
		}

		System.out.println(myList);

		myList.subList(10, 14).clear();
		myList.trimToSize();

		// ****************************************************************//

		IteratorDemo();

		checkEmpty();
		
		ListIteratorDemo();
		
		

	}

	void IteratorDemo() {
		ArrayList<String> al = new ArrayList<String>();

		al.add("C");
		al.add("A");
		al.add("E");
		al.add("B");
		al.add("D");
		al.add("F");

		System.out.print("Original contents of al: ");
		Iterator<String> itr = al.iterator();
		while (itr.hasNext()) {
			String element = itr.next();
			System.out.print(element + " ");
		}
		System.out.println();

		ListIterator<String> litr = al.listIterator();
		while (litr.hasNext()) {
			String element = litr.next();
			litr.set(element + "+");
		}

		// Now, display the list backwards.
		System.out.print("Modified list backwards: ");
		while (litr.hasPrevious()) {
			String element = litr.previous();
			System.out.print(element + " ");
		}
	}

	void checkEmpty() {
		List list = Arrays.asList(new String[] { "A", "B", "C", "D" });
		System.out.println(list.size());
		System.out.println(list.isEmpty());
	}

	void ListIteratorDemo() {
		ArrayList<String> al = new ArrayList<String>();

		al.add("C");
		al.add("A");
		al.add("E");
		al.add("B");
		al.add("D");
		al.add("F");

		System.out.print("Original contents of al: ");
		Iterator<String> itr = al.iterator();
		while (itr.hasNext()) {
			String element = itr.next();
			System.out.print(element + " ");
		}
		System.out.println();

		ListIterator<String> litr = al.listIterator();
		while (litr.hasNext()) {
			String element = litr.next();
			litr.set(element + "+");
		}

		// Now, display the list backwards.
		System.out.print("Modified list backwards: ");
		while (litr.hasPrevious()) {
			String element = litr.previous();
			System.out.print(element + " ");
		}
	}


}

Download complete tutorial PDF from here.

Please check the LogCat for Output.

One thought on “All about ArrayList – Android.

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