Java programs

Java programming: Java program code consists of instructions which will be executed on your computer system to perform a task as an example say arrange given integers in ascending order. This page contains examples for beginners to understand how to use java programming to write simple Java programs. These codes demonstrate how to get input from user, working with loops, strings and arrays. Programs are provided with output (image file) and you can also download class file and execute it directly without compiling the source file.

Compiling and executing java programs

Java programming software: To compile and run Java program code you need to download JDK (Java Development Kit).

To compile type: javac file_name.java where file_name is name of file containing java source code.
Javac is the Java compiler which converts java code into bytecode.

To run type: java main_method_class where main_method_class is the name of class which defines main method.

Learn Java through books

If you are just starting to learn Java then it is recommended to buy Java programming book. A Java book will help you to easy learn basic concepts and will act as a reference for all time.

Java programming examples

Example 1: Display message on computer screen.

class First {
  public static void main(String[] arguments) {
    System.out.println("Let's do something using Java technology.");
  }
}

This is similar to hello world java program. Download java programming class file.

Output of program:
Java program output

Example 2: Print integers

class Integers {
  public static void main(String[] arguments) {
    int c; //declaring a variable
 
  /* Using for loop to repeat instruction execution */
 
    for (c = 1; c <= 10; c++) {
      System.out.println(c);
    }
  }
}

Output:
10 natural numbers java program

If else control instructions:

class Condition {
  public static void main(String[] args) {
    boolean learning = true;
 
    if (learning) {
      System.out.println("Java programmer");
    }
    else {
      System.out.println("What are you doing here?");
    }
  }
}

Output:
If else java program

Command line arguments:

class Arguments {
  public static void main(String[] args) {
    for (String t: args) {
      System.out.println(t);
    }
  }
}

Command line arguments

Java programming language

Below is the list of java programs which will help you in learn java programming language.

Java Development IDE

As your programming experience grows in Java you may be developing your own project or software, using a simple text editor is not recommended. Following are two popular and open source IDE's:

Using IDE helps you a lot while coding as they offer many useful features such as you can create GUI in Netbeans without writing any code, Netbeans will show you any compilation error before you compile your code and it can also show hints on how to fix that.

Java programming tutorial

Java technology has changed our life as most of devices we use today includes java that's why to learn java programming is a good thing. Java was developed by Sun Microsystems but now owned by Oracle. Here is a quick java tutorial for beginners, Java is an object oriented computer programming like C++, if you already know C++ or any other object oriented language then it will be easier for you to learn java. Java program consists of classes which contain methods, you can't write a method outside a class. Objects are instances of classes. Consider the following code:

class ProgrammingLanguage {
  //attributes
  String language_name;
  String language_type;
 
  //constructor
  ProgrammingLanguage(String n, String t) {
    language_name = n;
    language_type = t;
  }
 
  //main method
  public static void main(String[] args) {
    //creating objects of class
    ProgrammingLanguage C = new ProgrammingLanguage("C", "Procedural");
    ProgrammingLanguage Cpp = new ProgrammingLanguage("C++", "Object oriented");
 
    //calling method    
    C.display();
    Cpp.display();
  }
 
  //method (function in C++ programming)
  void display() {
    System.out.println("Language name:"+language_name);
    System.out.println("Language type:"+language_type);
  }
}

There is a ProgrammingLanguage class and all programming languages will be instances of this class. We have considered only two attributes language name and type, we can create instances of class using new keyword. There is a constructor method which is invoked when an object of class is created we use it to name the programming language and its type. Main method is a must and acts as starting point of program, display method is used to print information about programming language object. Class names in java begin with a capital letter and if there are more words in class then their first letter will also be capital, for example MyJavaClass is a class name and for methods (functions in C or C++) first letter is small and other words first letter is capital as an example myJava is method name. These are only conventions, but are useful in distinguishing classes from methods. Java has a very rich API to build desktop and web applications.

Java programming PDF

If you like to learn using PDF books then try learning java from following e-books:
Java programming language handbook 2.85 MB.
Introduction to programming using Java 5.99 MB.

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