	public void click_btn_finish(View view)
	{
		printErr(false, ""); 
		double solution = 0;
		boolean error_occurred = false;
		String leftOpStr = lOperand.getText().toString();
		String rightOpStr = rOperand.getText().toString();
		char operator = ((String) txt_signPlaceholder.getText()).charAt(0);
		double leftOperand = 0, rightOperand = 0;
		try
		{
			leftOperand = Double.parseDouble(leftOpStr);
		} catch (NumberFormatException e)
		{
			error_occurred = true;
			printErr(true, "Enter a valid number as the left operand.\n");
		}
		try
		{
			rightOperand = Double.parseDouble(rightOpStr);
		} catch (NumberFormatException e)
		{
			error_occurred = true;
			printErr(true, "Enter a valid number as the right operand.\n");
		}
		if (!error_occurred)
		{
			try
			{
				solution = Calculator.calculate(leftOperand, operator,
						rightOperand);
			} catch (ArithmeticException a)
			{
				printErr(true,
						"Cannot Divide by Zero! Some men just want to watch the world burn!\n");
			} catch (IllegalArgumentException i)
			{
				printErr(true, "Please select an operator.\n");
			}
		}
		if (!error_occurred)
			outputBox.setText("Answer: " + solution);
		else
			outputBox.setText("Answer: ");
	}

	public void click_btn_finish(View view)
	{
		printErr(false, ""); 
		double solution = 0;
		boolean error_occurred = false;
		String leftOpStr = lOperand.getText().toString();
		String rightOpStr = rOperand.getText().toString();
		char operator = ((String) txt_signPlaceholder.getText()).charAt(0);
		double leftOperand = 0, rightOperand = 0;
		try
		{
			leftOperand = Double.parseDouble(leftOpStr);
		} catch (NumberFormatException e)
		{
			error_occurred = true;
			printErr(true, "Enter a valid number as the left operand.\n");
		}
		try
		{
			rightOperand = Double.parseDouble(rightOpStr);
		} catch (NumberFormatException e)
		{
			error_occurred = true;
			printErr(true, "Enter a valid number as the right operand.\n");
		}
		if (!error_occurred)
		{
			try
			{
				solution = Calculator.calculate(leftOperand, operator,
						rightOperand);
			} catch (ArithmeticException a)
			{
				printErr(true,
						"Cannot Divide by Zero! Some men just want to watch the world burn!\n");
				error_occurred=true; 
			} catch (IllegalArgumentException i)
			{
				printErr(true, "Please select an operator.\n");
				error_occurred=true;
			}
		}
		if (!error_occurred)
			outputBox.setText("Answer: " + solution);
		else
			outputBox.setText("Answer: ");
	}
