regex101: Find Program Java

Regular Expression

(((import java\.)[a-zA-Z\.\*]*;)|(public static void main(.*))|(class\s[a-zA-Z_$]+[\s]*\{)|(System\.out\.print))

Test String
New

/*
        Calculate Circle Area using Java Example
        This Calculate Circle Area using Java Example shows how to calculate
        area of circle using it's radius.
*/
 
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
 
public class CalculateCircleAreaExample {
 
        public static void main(String[] args) {
               
                int radius = 0;
                System.out.println("Please enter radius of a circle");
               
                try
                {
                        //get the radius from console
                        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
                        radius = Integer.parseInt(br.readLine());
                }
                //if invalid value was entered
                catch(NumberFormatException ne)
                {
                        System.out.println("Invalid radius value" + ne);
                        System.exit(0);
                }
                catch(IOException ioe)
                {
                        System.out.println("IO Error :" + ioe);
                        System.exit(0);
                }
               
                /*
                 * Area of a circle is
                 * pi * r * r
                 * where r is a radius of a circle.
                 */
               
                //NOTE : use Math.PI constant to get value of pi
                double area = Math.PI * radius * radius;
               
                System.out.println("Area of a circle is " + area);
        }
}
 
/*
Output of Calculate Circle Area using Java Example would be
Please enter radius of a circle
19
Area of a circle is 1134.1149479459152
*/

@@@@

/*
        Calculate Rectangle Area using Java Example
        This Calculate Rectangle Area using Java Example shows how to calculate
        area of Rectangle using it's length and width.
*/
 
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
 
public class CalculateRectArea {
 
        public static void main(String[] args) {
               
                int width = 0;
                int length = 0;
                       
                try
                {
                        //read the length from console
                        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
                       
                        System.out.println("Please enter length of a rectangle");
                        length = Integer.parseInt(br.readLine());
 
                        //read the width from console
                        System.out.println("Please enter width of a rectangle");
                        width = Integer.parseInt(br.readLine());
                       
                       
                }
                //if invalid value was entered
                catch(NumberFormatException ne)
                {
                        System.out.println("Invalid value" + ne);
                        System.exit(0);
                }
                catch(IOException ioe)
                {
                        System.out.println("IO Error :" + ioe);
                        System.exit(0);
                }
               
                /*
                 * Area of a rectangle is
                 * length * width
                */
               
                int area = length * width;
               
                System.out.println("Area of a rectangle is " + area);
        }
               
}
 
/*
Output of Calculate Rectangle Area using Java Example would be
Please enter length of a rectangle
10
Please enter width of a rectangle
15
Area of a rectangle is 150
*/

@@@@

/*
        Java Factorial Using Recursion Example
        This Java example shows how to generate factorial of a given number
        using recursive function.
*/
 
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
 
public class JavaFactorialUsingRecursion {
       
        public static void main(String args[]) throws NumberFormatException, IOException{
               
                System.out.println("Enter the number: ");
               
                //get input from the user
                BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
                int a = Integer.parseInt(br.readLine());
               
                //call the recursive function to generate factorial
                int result= fact(a);
               
               
                System.out.println("Factorial of the number is: " + result);
        }
       
        static int fact(int b)
        {
                if(b <= 1)
                        //if the number is 1 then return 1
                        return 1;
                else
                        //else call the same function with the value - 1
                        return b * fact(b-1);
        }
}
 
/*
Output of this Java example would be
 
Enter the number:
5
Factorial of the number is: 120
*/

@@@@

/*
        Swap Numbers Without Using Third Variable Java Example
        This Swap Numbers Java Example shows how to
        swap value of two numbers without using third variable using java.
*/
 
public class SwapElementsWithoutThirdVariableExample {
 
        public static void main(String[] args) {
               
                int num1 = 10;
                int num2 = 20;
               
                System.out.println("Before Swapping");
                System.out.println("Value of num1 is :" + num1);
                System.out.println("Value of num2 is :" +num2);
               
                //add both the numbers and assign it to first
                num1 = num1 + num2;
                num2 = num1 - num2;
                num1 = num1 - num2;
               
                System.out.println("Before Swapping");
                System.out.println("Value of num1 is :" + num1);
                System.out.println("Value of num2 is :" +num2);
        }
 
 
}
 
/*
Output of Swap Numbers Without Using Third Variable example would be
Before Swapping
Value of num1 is :10
Value of num2 is :20
Before Swapping
Value of num1 is :20
Value of num2 is :10
*/

@@@@

// OddEven.java
import javax.swing.JOptionPane;
 
public class OddEven {
    /**
     * "input" is the number that the user gives to the computer
     */
    private int input; // a whole number("int" means integer)
 
    /**
     * This is the constructor method. It gets called when an object of the OddEven type
     * is being created.
     */
    public OddEven() {
        /*
         * In most Java programs constructors can initialize objects with default values, or create
         * other objects that this object might use to perform its functions. In some Java programs, the
         * constructor may simply be an empty function if nothing needs to be initialized prior to the
         * functioning of the object. In this program's case, an empty constructor would suffice.
         * A constructor must exist; however, if the user doesn't put one in then the compiler
         * will create an empty one.
         */
    }
 
    /**
     * This is the main method. It gets called when this class is run through a Java interpreter.
     * @param args command line arguments (unused)
     */
    public static void main(final String[] args) {
       /*
        * This line of code creates a new instance of this class called "number" (also known as an
        * Object) and initializes it by calling the constructor. The next line of code calls
        * the "showDialog()" method, which brings up a prompt to ask you for a number
        */
       OddEven number = new OddEven();
       number.showDialog();
    }
 
    public void showDialog() {
        /*
         * "try" makes sure nothing goes wrong. If something does,
         * the interpreter skips to "catch" to see what it should do.
         */
        try {
            /*
             * The code below brings up a JOptionPane, which is a dialog box
             * The String returned by the "showInputDialog()" method is converted into
             * an integer, making the program treat it as a number instead of a word.
             * After that, this method calls a second method, calculate() that will
             * display either "Even" or "Odd."
             */
            this.input = Integer.parseInt(JOptionPane.showInputDialog("Please enter a number."));
            this.calculate();
        } catch (final NumberFormatException e) {
            /*
             * Getting in the catch block means that there was a problem with the format of
             * the number. Probably some letters were typed in instead of a number.
             */
            System.err.println("ERROR: Invalid input. Please type in a numerical value.");
        }
    }
 
    /**
     * When this gets called, it sends a message to the interpreter.
     * The interpreter usually shows it on the command prompt (For Windows users)
     * or the terminal (For *nix users).(Assuming it's open)
     */
    private void calculate() {
        if ((this.input % 2) == 0) {
            JOptionPane.showMessageDialog(null, "Even");
        } else {
            JOptionPane.showMessageDialog(null, "Odd");
        }
    }
}

Regular Expression

Test StringNew

Test String
New