Thursday 29 November 2012

Get Sub List of Java ArrayList Example

By Unknown 05:39 Leave a Comment
  1. import java.util.ArrayList;
  2. import java.util.List;
  3.  
  4. public class GetSubListOfJavaArrayListExample {
  5.  
  6.   public static void main(String[] args) {
  7.  
  8.     //create an ArrayList object
  9.     ArrayList arrayList = new ArrayList();
  10.    
  11.     //Add elements to Arraylist
  12.     arrayList.add("1");
  13.     arrayList.add("2");
  14.     arrayList.add("3");
  15.     arrayList.add("4");
  16.     arrayList.add("5");
  17.    
  18.     /*
  19.        To get a sub list of Java ArrayList use
  20.        List subList(int startIndex, int endIndex) method.
  21.        This method returns an object of type List containing elements from
  22.        startIndex to endIndex - 1.
  23.     */
  24.    
  25.     List lst = arrayList.subList(1,3);
  26.        
  27.     //display elements of sub list.
  28.     System.out.println("Sub list contains : ");
  29.     for(int i=0; i< lst.size() ; i++)
  30.       System.out.println(lst.get(i));
  31.      
  32.     /*
  33.       Sub List returned by subList method is backed by original Arraylist. So any
  34.       changes made to sub list will also be REFLECTED in the original Arraylist.
  35.     */
  36.     //remove one element from sub list
  37.     Object obj = lst.remove(0);
  38.     System.out.println(obj + " is removed from sub list");
  39.    
  40.     //print original ArrayList
  41.     System.out.println("After removing " + obj + " from sub list, original ArrayList contains : ");
  42.     for(int i=0; i< arrayList.size() ; i++)
  43.       System.out.println(arrayList.get(i));
  44.    
  45.   }
  46.  
  47. }
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Sort Element Of ArrayList In Java

By Unknown 05:28 Leave a Comment
  1. import java.util.ArrayList;
  2. import java.util.Collections;
  3.  
  4. public class SortJavaArrayListExample {
  5.  
  6.   public static void main(String[] args) {
  7.    
  8.     //create an ArrayList object
  9.     ArrayList arrayList = new ArrayList();
  10.    
  11.     //Add elements to Arraylist
  12.     arrayList.add("1");
  13.     arrayList.add("3");
  14.     arrayList.add("5");
  15.     arrayList.add("2");
  16.     arrayList.add("4");
  17.  
  18.     /*
  19.       To sort an ArrayList object, use Collection.sort method. This is a
  20.       static method. It sorts an ArrayList object's elements into ascending order.
  21.     */
  22.     Collections.sort(arrayList);
  23.    
  24.     //display elements of ArrayList
  25.     System.out.println("ArrayList elements after sorting in ascending order : ");
  26.     for(int i=0; i<arrayList.size(); i++)
  27.       System.out.println(arrayList.get(i));
  28.  
  29.   }
  30. }
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Search an element from ArrayList

By Unknown 05:25 Leave a Comment
import java.util.ArrayList;


public class SearchElementInArrayList
{
   public static void main(String args[])
   {
       ArrayList arrList=new ArrayList();
      
       arrList.add("1");
       arrList.add("2");
       arrList.add("3");
      
       Boolean flag=arrList.contains("1");
      
       System.out.println("Contains?= "+flag);
      
       int indexNum=arrList.indexOf("1");
      
       System.out.println("Index= "+indexNum);
      
   }
}
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Replace an element in arraylist

By Unknown 05:18 Leave a Comment
import java.util.ArrayList;


public class ReplaceElementInArrayList
{
   
    public static void main(String args[])
    {
        ArrayList arrList=new ArrayList();
       
        arrList.add("Harit");
        arrList.add("Lalit");
       
        for(Object list:arrList)
        {
            System.out.println(list);
        }
       
        arrList.set(0,"Nikki");
       
        for(Object list:arrList)
        {
            System.out.println(list);
        }
    }

}
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Remove an element from specified index of Java ArrayList Example

By Unknown 05:13 Leave a Comment
  1. import java.util.ArrayList;
  2.  
  3. public class RemoveElementFromArrayListExample {
  4.  
  5.   public static void main(String[] args) {
  6.     //create an ArrayList object
  7.     ArrayList arrayList = new ArrayList();
  8.    
  9.     //Add elements to Arraylist
  10.     arrayList.add("1");
  11.     arrayList.add("2");
  12.     arrayList.add("3");
  13.    
  14.     /*
  15.       To remove an element from the specified index of ArrayList use
  16.       Object remove(int index) method.
  17.       It returns the element that was removed from the ArrayList.
  18.     */
  19.     Object obj = arrayList.remove(1);
  20.     System.out.println(obj + " is removed from ArrayList");
  21.    
  22.     System.out.println("ArrayList contains...");
  23.     //display elements of ArrayList
  24.     for(int index=0; index < arrayList.size(); index++)
  25.       System.out.println(arrayList.get(index));
  26.    
  27.   }
  28. }
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Remove all elements from Java ArrayList Example

By Unknown 05:11 Leave a Comment
  1. import java.util.ArrayList;
  2.  
  3. public class RemoveAllElementsOfArrayListExample {
  4.  
  5.   public static void main(String[] args) {
  6.     //create an ArrayList object
  7.     ArrayList arrayList = new ArrayList();
  8.    
  9.     //Add elements to Arraylist
  10.     arrayList.add("1");
  11.     arrayList.add("2");
  12.     arrayList.add("3");
  13.    
  14.     System.out.println("Size of ArrayList before removing elements : "
  15.                                                        + arrayList.size());
  16.     /*
  17.       To remove all elements from the ArrayList use
  18.       void clear() method.
  19.     */
  20.     arrayList.clear();
  21.     System.out.println("Size of ArrayList after removing elements : "
  22.                                                        + arrayList.size());
  23.    
  24.   }
  25. }
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Iterate a ArrayList Using Iterator

By Unknown 05:10 Leave a Comment
  1. import java.util.ArrayList;
  2. import java.util.Iterator;
  3.  
  4. public class IterateThroughArrayListUsingIteratorExample {
  5.  
  6.   public static void main(String[] args) {
  7.    
  8.     //create an ArrayList object
  9.     ArrayList arrayList = new ArrayList();
  10.    
  11.     //Add elements to Arraylist
  12.     arrayList.add("1");
  13.     arrayList.add("2");
  14.     arrayList.add("3");
  15.     arrayList.add("4");
  16.     arrayList.add("5");
  17.    
  18.     //get an Iterator object for ArrayList using iterator() method.
  19.     Iterator itr = arrayList.iterator();
  20.    
  21.    
  22.     System.out.println("Iterating through ArrayList elements...");
  23.     while(itr.hasNext())
        {
  24.       System.out.println(itr.next());
  25.     }
  26.   }
  27. }
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Insert all elements of other Collection to Specified Index of Java ArrayList Example

By Unknown 05:07 Leave a Comment
  1. import java.util.ArrayList;
  2. import java.util.Vector;
  3.  
  4. public class InsertAllElementsOfOtherCollectionToArrayListExample {
  5.  
  6.   public static void main(String[] args) {
  7.  
  8.     //create an ArrayList object
  9.     ArrayList arrayList = new ArrayList();
  10.    
  11.     //Add elements to Arraylist
  12.     arrayList.add("1");
  13.     arrayList.add("2");
  14.     arrayList.add("3");
  15.    
  16.     //create a new Vector object
  17.     Vector v = new Vector();
  18.     v.add("4");
  19.     v.add("5");
  20.    
  21.    
  22.     //insert all elements of Vector to ArrayList at index 1
  23.     arrayList.addAll(1,v);
  24.    
  25.     //display elements of ArrayList
  26.     System.out.println("After inserting all elements of Vector at index 1,
  27.                                                    ArrayList contains..");
  28.     for(int i=0; i<arrayList.size(); i++)
  29.       System.out.println(arrayList.get(i));
  30.  
  31.   }
  32. }
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Wednesday 28 November 2012

Copy all elements of Java ArrayList to an Object Array Example

By Unknown 03:48 Leave a Comment
mport java.util.ArrayList;

public class CopyElementsOfArrayListToArrayExample {

  public static void main(String[] args) {
    //create an ArrayList object
    ArrayList arrayList = new ArrayList();
  
    //Add elements to ArrayList
    arrayList.add("1");
    arrayList.add("2");
    arrayList.add("3");
    arrayList.add("4");
    arrayList.add("5");
  
    /*
      To copy all elements of java ArrayList object into array use
      Object[] toArray() method.
    */
  
    Object[] objArray = arrayList.toArray();
  
    //display contents of Object array
    System.out.println("ArrayList elements are copied into an Array.
                                                  Now Array Contains..");
    for(int index=0; index < objArray.length ; index++)
      System.out.println(objArray[index]);
  }
}
 
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Append all elements of other Collection to Java ArrayList Example

By Unknown 03:01 Leave a Comment

import java.util.ArrayList;
import java.util.Vector;

public class AppendAllElementsOfOtherCollectionToArrayListExample {

  public static void main(String[] args) {

    //create an ArrayList object
    ArrayList arrayList = new ArrayList();
   
    //Add elements to Arraylist
    arrayList.add("1");
    arrayList.add("2");
    arrayList.add("3");
   
    //create a new Vector object
    Vector v = new Vector();
    v.add("4");
    v.add("5");
   

    
    //append all elements of Vector to ArrayList
    arrayList.addAll(v);
   
    //display elements of ArrayList
    System.out.println("After appending all elements of Vector,ArrayList contains..");

     for(int i=0; i<arrayList.size(); i++)
      System.out.println(arrayList.get(i));

  }
}


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Array List

By Unknown 02:50 Leave a Comment

ArrayList

 Java ArrayList is a resizable array which implements List interface. ArrayList provides all operation defined by List interface. Internally ArrayList uses an array to store its elements. ArrayList provides additional methods to manipulate the array that actually stores the elements.

 ArrayList is equivalent to Vector, but ArrayList is not synchronized.

 Java ArrayList Capacity

 Capacity of an ArrayList is the size of the array used to store the list elements. It grows automatically as we add elements to it. Every time this happens, the internal array has to be reallocated. This increases the load.

 We can set the initial capacity of the ArrayList using following method.

 ArrayList arrayList = new ArrayList();
arrayList.ensureCapacity(100);

 Java ArrayList Iterators
Java ArrayList provides two types of Iterators.
1) Iterator
2) ListIterator

 Iterator iterator = arrayList.iterator();

 Returns object of Iterator.

 ListIterator listIterator = arrayList.listIterator();

 Returns object of ListIterator.

 ListIterator listIterator = arrayList.listIterator(int startIndex);

 Returns object of ListIterator. The first next() method call on this ListIterator object will return the element at the specified index passed to get the ListIterator object.

 Iterators returned by these methods are fail-fast. That means if the list is modified after getting the Iterator by using some other means rather than Iterators own add or remove method, Iterator will throw ConcurrentModificationException.

 ArrayList Constructors

 1) ArrayList()
Creates an empty ArrayList.

 For example,
ArrayList arrayList = new ArrayList();

 2) ArrayList(int capacity)
Creates an ArrayList with specified initial capacity.

 For example,
ArrayList arrayList = new ArrayList(10);

 3) ArrayList(Collection c)
Creates an ArrayList containing elements of the collection specified.

 For example,
ArrayList arrayList = new ArrayList(myCollection);

 Where myCollection is an object of the type Collection. This creates an ArrayList of elements contained in the myCollection, in the order returned by the myCollection’s Iterator.

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Tuesday 20 November 2012

Add or substract hours to current time using Java Calendar

By Unknown 04:43 Leave a Comment

  1. /*
  2.   Add or substract hours to current time using Java Calendar
  3.   This example shows how to add or substract hours in current time  
  4.   using Java Calendar class.
  5. */
  6.  
  7. import java.util.Calendar;
  8.  
  9. public class AddHoursToCurrentDate {
  10.  
  11.   public static void main(String[] args) {
  12.    
  13.     //create Calendar instance
  14.     Calendar now = Calendar.getInstance();
  15.  
  16.     System.out.println("Current Date : " + (now.get(Calendar.MONTH) + 1)
  17.                         + "-"
  18.                         + now.get(Calendar.DATE)
  19.                         + "-"
  20.                         + now.get(Calendar.YEAR));
  21.    
  22.     System.out.println("Current time : " + now.get(Calendar.HOUR_OF_DAY)
  23.                       + ":"
  24.                       + now.get(Calendar.MINUTE)
  25.                       + ":"
  26.                       + now.get(Calendar.SECOND));
  27.                      
  28.     //add hours to current date using Calendar.add method
  29.     now.add(Calendar.HOUR,10);
  30.  
  31.     System.out.println("New time after adding 10 hours : "
  32.                       + now.get(Calendar.HOUR_OF_DAY)
  33.                       + ":"
  34.                       + now.get(Calendar.MINUTE)
  35.                       + ":"
  36.                       + now.get(Calendar.SECOND));
  37.  
  38.     /*
  39.      * Java Calendar class automatically adjust the date accordingly if adding
  40.      * hours to the current time causes current date to be changed.
  41.      */
  42.      
  43.     System.out.println("New date after adding 10 hours : "
  44.                         + (now.get(Calendar.MONTH) + 1)
  45.                         + "-"
  46.                         + now.get(Calendar.DATE)
  47.                         + "-"
  48.                         + now.get(Calendar.YEAR));
  49.    
  50.     //substract hours from current date using Calendar.add method
  51.     now = Calendar.getInstance();
  52.     now.add(Calendar.HOUR, -3);
  53.  
  54.     System.out.println("Time before 3 hours : " + now.get(Calendar.HOUR_OF_DAY)
  55.                       + ":"
  56.                       + now.get(Calendar.MINUTE)
  57.                       + ":"
  58.                       + now.get(Calendar.SECOND));
  59.    
  60.   }
  61. }
  62.  
  63. /*
  64. Typical output would be
  65. Current Date : 12-25-2007
  66. Current time : 18:31:42
  67. New time after adding 10 hours : 4:31:42
  68. New date after adding 10 hours : 12-26-2007
  69. Time before 3 hours : 15:31:42
  70. */
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Add or substract days to current date using Java Calendar

By Unknown 04:37 Leave a Comment

  1. /*
  2.   Add or substract days to current date using Java Calendar
  3.   This example shows how to add or substract days in current date and time values
  4.   using Java Calendar class.
  5. */
  6.  
  7. import java.util.Calendar;
  8.  
  9. public class AddDaysToCurrentDate {
  10.  
  11.   public static void main(String[] args) {
  12.    
  13.     //create Calendar instance
  14.     Calendar now = Calendar.getInstance();
  15.    
  16.     System.out.println("Current date : " + (now.get(Calendar.MONTH) + 1)
  17.                         + "-"
  18.                         + now.get(Calendar.DATE)
  19.                         + "-"
  20.                         + now.get(Calendar.YEAR));
  21.    
  22.     //add days to current date using Calendar.add method
  23.     now.add(Calendar.DATE,1);
  24.  
  25.     System.out.println("date after one day : " + (now.get(Calendar.MONTH) + 1)
  26.                         + "-"
  27.                         + now.get(Calendar.DATE)
  28.                         + "-"
  29.                         + now.get(Calendar.YEAR));
  30.  
  31.    
  32.     //substract days from current date using Calendar.add method
  33.     now = Calendar.getInstance();
  34.     now.add(Calendar.DATE, -10);
  35.  
  36.     System.out.println("date before 10 days : " + (now.get(Calendar.MONTH) + 1)
  37.                         + "-"
  38.                         + now.get(Calendar.DATE)
  39.                         + "-"
  40.                         + now.get(Calendar.YEAR));
  41.    
  42.   }
  43. }
  44.  
  45. /*
  46. Typical output would be
  47. Current date : 12-25-2007
  48. date after one day : 12-26-2007
  49. date before 10 days : 12-15-2007
  50. */
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