How to make an input loop in the method?
<p>When I input motherHeight and fatherHeight then they will calculate the height of the child. But how do I add a loop so when the height of the child is zero or less, that should give an error message and try again?</p>

<pre><code>import java.util.Scanner;

public class estimateHeight {
    private static Scanner kb = new Scanner(System.in);
    private static Scanner kbNum = new Scanner(System.in);

    public static void calculateHeight(char gender, float motherHeight, float fatherHeight ) {
        float height = 0;
        if(gender == 'm' || gender == 'M')
            height = ((motherHeight * 13/12) + fatherHeight )/2;
        else
            height = ((fatherHeight * 12/13) + motherHeight)/2;

        if(height &lt;= 0) {
            System.out.println("Invalid inputs, please reneter: " );
            calculateHeight(gender, motherHeight, fatherHeight);
        }
        else
            System.out.println("The child's height is: " + height);
    }

    public static void main(String[] args) {
        System.out.println("Estimating the Adult Height of a Child. Press Q or -1 to quit.\n");

        String genderSelect;
        float fatherHeight, motherHeight;

        System.out.print("Gender? (m/f): ");
        genderSelect = kb.nextLine();
        if(genderSelect.equalsIgnoreCase("q"))
            System.exit(0);
        while(!(genderSelect.equalsIgnoreCase("m") || genderSelect.equalsIgnoreCase("f"))) {
            System.out.print("Invalid. Gender? (m/f): ");
            genderSelect = kb.nextLine();
        }

        System.out.print("Father's height? ");
        fatherHeight = kbNum.nextFloat();
        if(fatherHeight == -1)
            System.exit(0);

        System.out.print("Mother's height? ");
        motherHeight = kbNum.nextFloat();
        if(motherHeight == -1)
            System.exit(0);

        calculateHeight(genderSelect.charAt(0), motherHeight, fatherHeight);
    }
}
</code></pre>
