How to Compile and Run your First Java Program
By Chaitanya Singh | Filed Under: Learn Java
In this tutorial, we will see how to write, compile and run a java program. I will also cover java syntax, code conventions and several ways to run a java program.
Simple Java Program:
Output: This is my first program in java
How to compile and run the above program
Prerequisite: You need to have java installed on your system. You can get the java from here.
Step 1: Open a text editor, like Notepad on windows and TextEdit on Mac. Copy the above program and paste it in the text editor.
You can also use IDE like Eclipse to run the java program but we will cover that part later in the coming tutorials. For the sake of simplicity, I will only use text editor and command prompt (or terminal) for this tutorial
Step 2: Save the file as FirstJavaProgram.java. You may be wondering why we have named the file as FirstJavaProgram, the thing is that we should always name the file same as the public class name. In our program, the public class name is FirstJavaProgram , that’s why our file name should be FirstJavaProgram.java.
Step 3: In this step, we will compile the program. For this, open command prompt (cmd) on Windows, if you are Mac OS then open Terminal.
To compile the program, type the following command and hit enter.
You may get this error when you try to compile the program: “javac’ is not recognized as an internal or external command, operable program or batch file“. This error occurs when the java path is not set in your system
If you get this error then you first need to set the path before compilation.
Set Path in Windows:
Open command prompt (cmd), go to the place where you have installed java on your system and locate the bin directory, copy the complete path and write it in the command like this.
Note: Your jdk version may be different. Since I have java version 1.8.0_121 installed on my system, I mentioned the same while setting up the path.
Set Path in Mac OS X
Open Terminal, type the following command and hit return.
Type the following command on terminal to confirm the path.
The steps above are for setting up the path temporary which means when you close the command prompt or terminal, the path settings will be lost and you will have to set the path again next time you use it. I will share the permanent path setup guide in the coming tutorial.
Step 4: After compilation the .java file gets translated into the .class file(byte code). Now we can run the program. To run the program, type the following command and hit enter:
Note that you should not append the .java extension to the file name while running the program.
Closer look to the First Java Program
Now that we have understood how to run a java program, let have a closer look at the program we have written above.
This is the first line of our java program. Every java application must have at least one class definition that consists of class keyword followed by class name. When I say keyword, it means that it should not be changed, we should use it as it is. However the class name can be anything.
I have made the class public by using public access modifier, I will cover access modifier in a separate post, all you need to know now that a java file can have any number of classes but it can have only one public class and the file name should be same as public class name.
This is our next line in the program, lets break it down to understand it:
public : This makes the main method public that means that we can call the method from outside the class.
static : We do not need to create object for static methods to run. They can run itself.
void : It does not return anything.
main : It is the method name. This is the entry point method from which the JVM can run your program.
(String[] args) : Used for command line arguments that are passed as strings. We will cover that in a separate post.
This method prints the contents inside the double quotes into the console and inserts a newline after.
Checkout these basic java programs before reading next topic:
Java Programs – Java Programming Examples with Output
By Chaitanya Singh | Filed Under: Java Examples
To understand a programming language you must practice the programs, this way you can learn the language faster. This page includes java programs on various java topics such as control statements, loops, classes & objects, functions, arrays etc. All the programs are tested and provided with the output. If you new to java and want to learn java before trying out these program, then read my Core Java Tutorials.
Java Programs
| Java Basic Programs |
|---|
| Java Program to Add two Numbers |
| Java Program to Check Even or Odd Number |
| Java Program to add two binary numbers |
| Java Program to add two complex numbers |
| Java Program to Multiply two Numbers |
| Java Program to check Leap Year |
| Java Program to check whether input character is vowel or consonant |
| Java Program to calculate compound interest |
| Java Program to calculate simple interest |
| Java Program to find quotient and remainder |
| Java Program to calculate power of a number |
| Java Strings Programs |
|---|
| Java Program to Convert char to String and String to Char |
| Java Program to find duplicate characters in a String |
| Java Program to check Palindrome String using Stack, Queue, For and While loop |
| Java Program to sort strings in alphabetical order |
| Java Program to reverse words in a String |
| Java Program to perform bubble sort on Strings |
| Java program to find occurrence of a character in a String |
| Java program to count vowels and consonants in a String |
| Java Arrays Programs |
|---|
| Java Program to Calculate average of numbers using Array |
| Java Program to Add the elements of an Array |
| Java Program to reverse an array |
| Java Program to sort an array in ascending order |
| Java Program to convert char Array to String |
| Java Program to Add Two Matrix Using Multi-dimensional Arrays |
| Java Recursion Programs |
|---|
| Java Program to Reverse a number using for, while loop and recursion |
| Java Program to check Palindrome string using Recursion |
| Java Program to Reverse a String using Recursion |
| Java Program to find Factorial of a number using Recursion |
| Java Programs on Numbers |
|---|
| Java Program to display first 100 prime numbers |
| Java Program to display prime numbers between 1 and 100 or 1 and n |
| Java program to break integer into digits |
| Java Program to check Prime Number |
| Java Program to check if a given number is perfect square |
| Java Program to find square root of a number without sqrt method |
| Java Program to print Armstrong numbers between a given range |
| Java Program to Find Sum of Natural Numbers |
| Java Program to check if a number is Positive or Negative |
| Java Program to generate Random Number |
| Java Program to check Armstrong number |
| Java Program to find GCD of two numbers |
| Java Program to find Largest of three numbers |
| Java Program to swap two numbers using bitwise operator |
| Java Program to find smallest of three numbers using ternary operator |
| Java Program to find largest of three numbers using ternary operator |
| Java Program to display alternate prime numbers |
| Java Program to display even numbers from 1 to n or 1 to 100 |
| Java Program to display odd numbers from 1 to n or 1 to 100 |
| Java Program to Find average of 3 numbers |
| Java Program to Find HCF and LCM of Two Numbers |
| Java Input/Output Programs |
|---|
| Java Program to read number from Standard Input |
| Java Program to Get IP Address |
| Java Program to get Input From User |
| Java Programs on Geometrical Calculations |
|---|
| Java Program to Calculate Area of Rectangle |
| Java Program to Calculate Area of Square |
| Java Program to Calculate the area of Triangle |
| Java Program to Calculate Area and Circumference of Circle |
| Java Sorting/Searching Programs |
|---|
| Java Program for bubble Sort Ascending or Descending Order |
| Java Program for Linear Search |
| Java Program for Binary Search |
| Java Program for Selection Sorting |
| Java Conversion Programs |
|---|
| Java Octal to Decimal conversion |
| Java Program to Convert Decimal to Octal |
| Java hexadecimal to decimal conversion |
| Java Program to convert decimal to hexadecimal |
| Java binary to octal conversion |
| Java String to boolean |
| Java program to convert boolean to String |
| Java int to char conversion |
| Java char to int conversion |
| Java char to string conversion |
| Java long to int conversion |
| Java int to long conversion |
| Java Program to Convert Decimal to Binary |
| Java Program to convert binary to Decimal |
| Java Program to find ASCII value of a character |
| Java program for String to int conversion |
| Java program to convert int to String |
| Java program for string to double conversion |
| Java program to convert double to String |
| Java program to convert String to long |
| Java program to convert long to String |
| Other Java Programs |
|---|
| Java Program to print Floyd’s triangle |
| Java program to print Pascal triangle |
| Java Program to display Fibonacci series using loops |
| Java Program to find Factorial using loops |
| Java Program to make a calculator using switch case |
| Java Program to Calculate grades of Student |
| Java Program to perform Arithmetic Operation using Method Overloading |
| Java Program to find Area of Geometric figures using method overloading |
Comments
i need some case studies on java programming
A very beautiful and well suited website —–> beginnersbook.com 😉
what is the error in this program
class p3
<
public static void main(int age)
<
if(age>=18)
<
system.out.println(“eligible for election”);
>
else
<
system.out.println(“not eligible for election”);
>
>
A function doesn’t contain a main method
pratham programmer says
your s should not be small in the statement “system. out. print…” . It should be capital S
Arpita Mandal says
Hey..there is a syntax error in your program!
The “s” of “system” must be in caps…that is,
It should be —
System.out.println(“eligible…”);
I hope it helps!!
> bracket error
Last > bracket are required
You can’t pass any argument in main method
Vamshi Krishna says
actually we can, they’re called as “command line arguments”
Ram panwar says
Yes we can pass argument in main function using command line argument..as a string
Deepak Kumar says
You can pass arguments in main method but only as String…..
public static void main(String []args) will come instead of public Static void main(int age)
Isuru Harischandra says
“int age” should be “String[] args” / “String args[]” / “String[] arg” / “String arg[]”
Mohit Tyagi says
1. main method should have String []args as arguments instead of age. Use public static void main(String args[])
2. age should be declared as a variable before using. Use int age=10;
3. System.out.println instead of system.out.println.
4.Closing bracket fro class p3 missing. Use > at last.
best java tutorial examples ever
This page is awesome For beginners…it is very helpful…give me example programs which will be useful for real time projects
How can I take an array for example five separate words and place them on separate lines evenly using astericks to make up the number on both ends in relation to the number entered by the user? Is a program to do this possible?
console application that receives any size of matrix and one parameter which is the Manhattan distance, this is K.
The result should be Yes/No. Yes if there are any two similar items (integers) in the matrix that are in a distance of K from each other or less.
Input: 1. Number of rows. 2. Matrix rows one line after the other in a new line between each matrix line. 3. K value. Output YES/NO Here is a sample for an input and output:
can you kindly provide program for the following
java a program to create an array of 10 integers. Accept values from the user in that array. Input another number from the user and find out how many numbers are equal to the number passed, how many are greater and how many are less than the number passed.
Nikhil Satpute says
# Suppose 450 is 3 digit number ….So 3 is its digit length. In that way calculate 5 digit random number ….do not run by using range ….get random number using length itself
How to convert char to numeric value
first U convert char to String with the method String s = String.valueof(char c), after this U convert String to numeric num like integer with Integer.parseint(String s)
Chaitanya Singh says
Chaitanya , your posts are awesome 😊
Muqtasid khan says
Write a program to accept the length of and breath of a rectangle using scanner class and display its area and perimeter
anisha garg says
can you please write a code on below question of complex number ??
Print the sum, difference and product of two complex numbers by creating a class named ‘Complex’ with separate methods for each operation whose real and imaginary parts are entered by user.
please add more programs like matrix all operation and no. of time vowels occurrence in a string
54321
4321
321
21
1 Write the structure of the program using for loop
DWAIPAYAN DUTTA says
X!/10+(X+2)!/15+(X+4)!/20+………n plz solve this.
GESII LEIBOR says
Write java program to find if a name exists in a list of names.The program should display how many times the name occurs in the list.The program should have at least two instance methods.
Siva kumar Nebarti says
Hi where can i get real time example programs such as
1 find out the no of persons in a room
2 Find the electricity bill for one month
Chaitanya Singh says
I will upload these programs soon.
I am new to java and I hope this beginnersbook.com would be very helpful to me. I am gonna start learning Java. Thank you very much.
Mohit Saini says
Very Well explained examples….. exact answers that are asked in interviews
Program for password it must contain one upper case and lower case and number and size of password 8-15
