public void calc() {

			if(operator== "+") {
				firstNum += secondNum;
				System.out.println("firstNum plus secondNum is: " + firstNum); }
			if(operator == "-"){
				firstNum -= secondNum;
			System.out.println("firstNum minus secondNum is: " + firstNum);}
			if(operator == "*") {
				firstNum *= secondNum;
			System.out.println("firstNum times secondNum is: " + firstNum);}
			if((operator == "/") && secondNum != 0.0){
				System.out.println("firstNum div by secondNum is: " + firstNum);
				firstNum /= secondNum;}
			if((operator == "/") && secondNum == 0.0){
				display.setText("ERROR");
				System.out.println(display.getText());
				firstNum = 0.0;
				secondNum = 0.0;
				operators = true;
				doClear = true;
			}
				
			if (!(display.getText().equals("ERROR"))) {
			operators = true;
			decPoint = false;

			display.setText(String.valueOf(firstNum));
		
			secondNum = firstNum;

			
			System.out.println("SecondNum is: " + firstNum);
		}

		}