Methods of ArrayList

1) add(Object o):

This method adds an element to ArrayList.

Eg:

public static void main(String[]args){

//creation of Arraylist with string arguments

//adding elements to Arraylist

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

al.add("India");

al.add("US");

al.add("Australia");

al.add("Germany");

al.add("Europe");

//Displaying elements of Arraylist

System.out.println(al);

}

Output:[India,US,Australia,Germany,Europe]

2)add(int index, object 0)

This method adds object 0 to  an ArrayList to at given index

Eg:

public static void main(String[]args){

//creation of Arraylist with string arguments

//adding elements to Arraylist

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

 al.add(0,"India");

al.add(1,"US");

al.add(2,"Australia");

al.add(3,"Germany");

al.add(4,"Europe");

 //Displaying elements of Arraylist

System.out.println(al);

}

Output:[India,US,Australia,Germany,Europe]

.

3)remove(int index)

Removes an element from given index.

public static void main(String[]args){

//creation of Arraylist with string arguments

//adding elements to Arraylist

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

al.add("India");

al.add("US");

al.add("Australia");

al.add("Germany");

al.add("Europe");

//Displaying elements of Arraylist before removing elements of ArrayList

System.out.println(al);

//after removing elements from ArrayList at specified index of ArrayList

al.remove(3);

//Displaying elements of Arraylist

System.out.println(al);

}

//Before removal

 Output[India,US,Australia,Germany,Europe]

//After removal

Output:[India,US,Australia,Europe]

4)remove(Object 0)

Removes an Object o from ArrayList.

public static void main(String[]args){

//creation of Arraylist with string arguments

//adding elements to Arraylist

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

al.add("India");

al.add("US");

al.add("Australia");

al.add("Germany");

al.add("Europe");

//Displaying elements of Arraylist before removing elements of ArrayList

System.out.println(al);

//after removing elements from ArrayList at specified index of ArrayList

al.remove("Germany");

//Displaying elements of Arraylist

System.out.println(al);

}

Output[India,US,Australia,Germany,Europe]

//after removal

Output:[India,US,Australia,Europe]

5)set(int index, Object o)

This method is used for Updating an element which replaces element present at specified index with object o.

public static void main(String[]args){

//creation of Arraylist with string arguments

//adding elements to Arraylist

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

al.add("India");

al.add("US");

al.add("Australia");

al.add("Germany");

al.add("Europe");

//Displaying elements of Arraylist before updating elements of ArrayList

System.out.println(al);

//after updating elements from ArrayList at specified index of ArrayList

al.set(2,"London");

//Displaying elements of Arraylist

System.out.println(al);

}

//before updating 

Output[India,US,Australia,Germany,Europe]

//after updating

Output:[India,US,London,Germany,Europe]

6)int indexOf(Object o)

This method gives the index of Object o. If the element is not found in the list it returns -1.

public static void main(String[]args){

//creation of Arraylist with string arguments

//adding elements to Arraylist

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

al.add(0,"India");

al.add(1,"US");

al.add(2,"Australia");

al.add(3,"Germany");

al.add(4,"Europe");

 //Displaying elements of Arraylist

al.indexOf("Australia");

System.out.println(al);

}

Output:2

7)Object get(int index )

It returns the object of list which is present at specified index.

public static void main(String[]args){

//creation of Arraylist with string arguments

//adding elements to Arraylist

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

al.add(0,"India");

al.add(1,"US");

al.add(2,"Australia");

al.add(3,"Germany");

al.add(4,"Europe");

//Displaying elements of Arraylist

 al.get(4);

System.out.println(al);

}

Output:Europe

8)int size()

It gives the size of Arraylist.

public static void main(String[]args){

//creation of Arraylist with string arguments

//adding elements to Arraylist

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

al.add(0,"India");

al.add(1,"US");

al.add(2,"Australia");

al.add(3,"Germany");

al.add(4,"Europe");

//Displaying size of elements of Arraylist

 al.size();

System.out.println(al);

}

Output: 5

9)boolean contains(Object o)

It checks whether the given object o is present in the arrayList .If  the element is present it returns true else returns false.

public static void main(String[]args){

//creation of Arraylist with string arguments

//adding elements to Arraylist

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

al.add(0,"India");

al.add(1,"US");

al.add(2,"Australia");

al.add(3,"Germany");

al.add(4,"Europe");

//Displaying size of elements of Arraylist

 al.contains("India");

System.out.println(al);

}

Output: true

10)Clear

This method is used to clear all the elements from Arraylist.

public static void main(String[]args){

//creation of Arraylist with string arguments

//adding elements to Arraylist

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

al.add(0,"India");

al.add(1,"US");

al.add(2,"Australia");

al.add(3,"Germany");

al.add(4,"Europe");

//Displaying size of elements of Arraylist

 al.clear();

System.out.println(al);

}

Output: []