Digits-Sum

Digits-Sum built on java, UI on window builder, building tool gradle.

• Simple project to check gradle building tool installation. Program sums all digits of given number:

IMPORTANT

• Popular error message is while trying to run jar file:

$ java -jar untitled-1.0-SNAPSHOT.jar
no main manifest attribute, in untitled-1.0-SNAPSHOT.jar

• To handle this, we have to add manifest file with the 'Main-Class' attribute to the JAR file in build.gradle file:

tasks.jar {
    manifest {
        attributes["Main-Class"] = "org.example.Main"
    }
}

---

Implementation

• Java Swing-based user interface (UI) class named UI. It creates a simple GUI window that allows the user to input a number and calculate the sum of its digits

• The code is in a package named gradleaf.

• The UI class extends the JFrame class to create a window-based UI.

• The UI consists of a panel named contentPane, which serves as the main container for UI components.

• The UI contains several UI components:

  • A JTextField named tfInput for the user to enter a number.
  • A JLabel named lbOutput to display the result of the sum.
  • A JLabel named lblNewLabel to display a title for the UI.
  • A JButton named btnSum to initiate the calculation.

• In the constructor of the UI class:

  • The UI window's title, size, and close operation are set.
  • The content pane's layout is set to null.
  • The UI components are created, positioned, and added to the content pane.
  • An action listener is added to the btnSum button, which listens for button clicks. When the button is clicked, the action listener's actionPerformed method is invoked.

• Inside the actionPerformed method:

  • The text entered in the tfInput field is retrieved using tfInput.getText().
  • The retrieved text is parsed into a Long value using Long.parseLong() and stored in inputDouble.
  • An instance of the sumDigits class (not provided) is created.
  • The sumDigits object's sumDigits method is called, passing inputDouble as an argument.
  • The returned result is cast to an int and stored in the result variable.
  • The result is converted to a String using Integer.toString() and stored in resultFinal.
  • The resultFinal string is set as the text of the lbOutput label.
  • The UI class does not define the sumDigits class, so the calculation logic for summing the digits of a number is missing. To make the code functional, you need to define the sumDigits class separately and provide its implementation.

• When the UI is launched and interacted with, it provides a simple input field for entering a number, a button to trigger the digit sum calculation, and a label to display the result.