/**
 * Implemented a simple arithmetic calculator in Java
 * using Swing toolkit for UI
 */
 
 package func;

public class MainCalc {
	
	public static void main(String[] args) {
		
		CalculatorUI operate = new CalculatorUI();
		operate.outputCalc();
		
	}
}

/**
 * Implemented a simple arithmetic calculator in Java
 * using Swing toolkit for UI
 */
 
package desktop_app;

public class MainCalc {
	
	public static void main(String[] args) {
		
		CalculatorUI operate = new CalculatorUI();
		operate.outputCalc();
		
	}
}

Update MainCalc.java