import javax.swing.JOptionPane;your text

public class Main {
public static void main(String[] args) {

    JOptionPane.showMessageDialog(null,"What Do You Want To Do?");
    String typeOfMath = JOptionPane.showInputDialog("Addition, Subtraction, Division, Multiplication, Find The Square Root?");

    String Addition;
    String Subtraction;
    String Division;
    String Multiplication;
    String SquareRoot;
    double z;

    if (typeOfMath == Addition) {
        double x = Double.parseDouble(JOptionPane.showInputDialog("Enter First Number"));
        double y = Double.parseDouble(JOptionPane.showInputDialog("Enter First Number"));
        z = x + y;
        JOptionPane.showMessageDialog(null, "The Answer Is: " + z);
    }else if (typeOfMath == Subtraction) {
        double x = Double.parseDouble(JOptionPane.showInputDialog("Enter First Number"));
        double y = Double.parseDouble(JOptionPane.showInputDialog("Enter First Number"));
        z = x - y;
        JOptionPane.showMessageDialog(null, "The Answer Is: " + z);
    }else if (typeOfMath == Division) {
        double x = Double.parseDouble(JOptionPane.showInputDialog("Enter First Number"));
        double y = Double.parseDouble(JOptionPane.showInputDialog("Enter First Number"));
        z = x / y;
        JOptionPane.showMessageDialog(null, "The Answer Is: " + z);
    }else if (typeOfMath == Multiplication) {
        double x = Double.parseDouble(JOptionPane.showInputDialog("Enter First Number"));
        double y = Double.parseDouble(JOptionPane.showInputDialog("Enter First Number"));
        z = x * y;
        JOptionPane.showMessageDialog(null, "The Answer Is: " + z);
    }else if (typeOfMath == SquareRoot){
        double x = Double.parseDouble(JOptionPane.showInputDialog("Enter The Number"));
        z = Math.sqrt(x);
        JOptionPane.showMessageDialog(null, "The Answer Is: " + z);
    }

    }
}

Can Someone help it says that strings addition, subtraction etc might not be initialized.