All about ArrayList – Android.

By | October 14, 2012
1 Comment
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.

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