Lists in java

By
Lists in java:
What is a list?
A list is collection of data.For a real time example consider a list of groceries for a month.You can add,remove,clear,get items from a list.List is actually an interface.
There are several lists collections available in java:
  1. Array list:Most important and useful type of list
  2. LinkedList:Similiar to arraylist with limited functionality
  3. Vector:Similiar to arraylist but it is synchronised class.
  4. Stack:LIFO(Last in first out) collection
Common methods in a list:
  1. add(Object e),add(int index,Object e):adds an element(duh :<).For adding element at specific position pass parameter index.
  2. remove(int index):remove an element at position
  3. clear():clears out the list.Make list empty.

Comments

Post a Comment

Popular posts from this blog

Basics of JDBC connectivity

By
JDBC connectivity: Or simplified as Java database connectivity.What is the fun when the program does not have a database to store to.So,here comes sql(a console based language specially for the data storage) to the rescue. Why is JDBC connectivity needed: Suppose you are working on large project called Library management and there are huge data to be stored and retrieved during the program execution.Such large data cannot be managed by simple file based databases.So,there is a need for a proper tool for this purpose.JDBC serves for this purpose.   How to do JDBC connectivity: First you will need jar file for JDBC driver. Link: JDBC driver for Mysql . If you are working on the eclipse,the right click on the project->project properties->java build path->(Bottom Left)add button->Path of the .jar file. Or you can create lib folder in your project and paste the jar file into it.That shoul work. JDBC connectivity is done in for steps: Loading the class with class...
Read more

Abstract class,Interfaces and its implementations

By
Image
Abstract class We need abstract class for the sense of simplicity.Learn it this way,suppose there is a college administration with over 100 of persons working in different sections namely,Head of department,teachers of diff. subjects,accounts department staff,mess staff,cleaners etc. Each have their own role in the college.But,here's the situation,what if the different department(classes) want the similar thing,for example,retrieving student info or getting the salary.We have to make method with similar motive,for each and every class we make,WHAT A WASTE!!! Abstract class comes to the rescue.  Abstract class is nothing but a normal class with some restrictions. Well,these restrictions are: At least one of the method/s must be abstract. You cannot make an object of an abstract class,i.e.,no new keyword before the class name.But the sub-classes of an abstract class is allowed. An abstract method MUST NOT HAVE A BODY.For example:void...
Read more

Concept of access specifiers,Simple programs in java

By
Access specifiers in java: What are access specifiers:They are keywords that restricts the access of the instance variable(data) and methods within a package,inherited classes or within the class There are basically 4 access specifiers in java: public:Gives access is in the package,other classes,within the class but cannot be accesses in another package.Free access to the variable in the whole project to be summed. private:Most restrictive,can access variable within the class only.Used for saving critical data. protected:Data and methods are access within the classes that are inherited to the current class only and within class access. default:Data and methods are accessible withing your package/project Simple programs in java Program to find the largest between two numbers: Code: class A { public static void main(String args[]) { int a=5; int b=10;           if(a>b)             {       ...
Read more