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List in java


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List in java

The List interface extends Collection and declares the behaviour of a collection that stores a sequence of elements.

·         Elements can be inserted or accessed by their position in the list, using a zero-based index.

·         A list may contain duplicate elements.

·         In addition to the methods defined by Collection.

·         Several of the list methods will throw an UnsupportedOperationException if the collection cannot be modified, and a ClassCastException is generated when one object is incompatible with another.

 

 We can define List data type which data type will be store in the list.

I.e.

List<String> myList=new ArrayList( );

// store only String type value

myList.add(" Data1");

myList.add(" Data2");

myList.add(" Data3");

or

List mList=new ArrayList( );

// store any type value

 

mList.add(" Data1");

mList.add(" Data2");

mList.add(" Data3");

 

In List class we can add several types of data but List<e> interface we can add only e type data for example

List mList=new ArrayList( );

mList.add(" Data1");

mList.add(123);

mList.add('C');

mList.add(3.63);

 

Insert value in list

Syntax -: listObj.add(Value);

                 myList.add("MyData");

 

Update value in particular index

Syntax -: listObj.set(int index, Value;

                  myList.set(4, "Update");

 

Find value from index

Syntax-: listobj.get(int index);

                myList.get(2);

 

Remove value from index

Syntax-: listobj.remove(int index);

                myList.remove(2);

 

Get index of Object

Syntax-: listobj.indexOf(Object);

int index=myList.indexOf("Data2");

If record found then return index position otherwise return -1.

 

 

Here I am creating example if List sample for insert, manipulation, deletion etc.

 

import java.util.ArrayList;

import java.util.List;

 

public class Demo {

     static List<String> myList;

 

     public static void main(String args[]) {

 

           myList = new ArrayList<String>();

           // insertData("Data1");

 

           for (int i = 1; i < 11; i++) {

                insertData("Item" + i);

 

           }

           updateList("Data10", 10);

           DeleteByData("Data10");

           DeleteByIndex(9);

           System.out.print(myList.toString());

 

     }

 

     public static void insertData(String data) {

           myList.add(data);

           // System.out.println("Data Inserted.");

 

     }

 

     public static void updateList(String data, int index) {

           index = index - 1;

           if (index < myList.size()) {

                myList.set(index, data);

                System.out.println("Data Updated.");

           } else

    System.out.println("You have not enough data index for update.");

     }

 

     public static void DeleteByIndex(int index) {

           index = index - 1;

           if (index < myList.size()) {

                myList.remove(index);

                System.out.println("Data Deleted.");

           } else

System.out.println("You have not enough data index for delete.");

 

     }

 

     public static void DeleteByData(String data) {

           int index = myList.indexOf(data);

           if (index >= 0) {

                myList.remove(index);

                System.out.println("Data Deleted.");

           } else

                System.out.println("Data not found for delete.");

     }

}

 

 

Output

 

 


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