First create simpledemo.java file.
Let's write below code into simpledemo.java file. Class name should be filename.
public class simpledemo {
public static void main(String[] args) {
System.out.println("welcome to java tutorials!");
}
}
Compile above code using below command.
javac simpledemo.java
Execute code using below command.
java simpledemo
It generates below output.
Output:
welcome to java tutorials!
When we compile Java program using javac tool, the Java compiler converts the source code (simpledemo.java) into byte code ( simpledemo.class).
public keyword in Java Program
public keyword is an access modifier. we can access public properties aneywhere java program. A class contains main method should be public.
class in Java Program
class keyword is used to declare a class in Java.
main method in Java Program
main represents the entry point for executing a Java program.
static in Java Program
if method is static, then we don't need to create object to access static method. The main() method is executed by the JVM, so it doesn't require creating an object to invoke the main() method. So, it saves memory.
void in Java Program
void is the return type of the method. It means it doesn't return any value.
String[] args or String args[] in Java Program
String[] args or String args[] is used for command line argument. We can pass array string argument in main method using command promt.
System.out.println() in Java Program
System.out.println() is used to print statement. System is a class, out is an object of the PrintStream class, println() is a method of the PrintStream class.
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