Hi,
On Jun 25, 8:36 am, [email protected] wrote:
> I tried to add codes to validate the input in the Exercise 3 of JAVA
> EXCEPTIONS AND ASSERTION.
> My purpose was to catch error for ALPHABETIC inputs. I'm confused why instead
> of executing the codes to catch NumberFormatException and then display the
> message "Input should be numeric" on JoptionPane, JAVA normal runtime error
> was displayed.
> This was the runtime error after inputting ALPHABETIC characters.
> Exception in thread "main" java.lang.NumberFormatException: For input string:
> "a"
> at
> java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
> at java.lang.Integer.parseInt(Integer.java:447)
> at java.lang.Integer.parseInt(Integer.java:497)
> at assertexample.Diamond.main(Main.java:43)
Just lookup the stacktrace. The exception is in Integer.parseInt().
When you look into your code, the Interger.parseInt() is not in the
try/catch block.
> These are the codes I added:catch (NumberFormatException e) {
> JOptionPane.showMessageDialog(null, "Input should be numeric. ");
> Below is the complete codes.
> Any help would be appreciated.
> Ray
> package assertexample;
> import javax.swing.*;
> class Diamond {
> static void printDiamond(int size) {
> String diamond = "";
> /* print upper triangle */
> for (int r = 1, a = 1; r <= size; r++, a+=2) {
> /* print spaces */
> for (int i = size - r; i >= 1; i--) {
> diamond += " ";
> }
> /* print *'s */
> for (int j = 1; j <= a; j++) {
> diamond += "*";
> }
> diamond += "\n";
> }
> /* print lower triangle */
> for (int r = size - 1, a = 2*(size-1)-1; r >= 1; r--, a-=2) {
> /* print spaces */
> for (int i = size - r; i >= 1; i--) {
> diamond += " ";
> }
> /* print *'s */
> for (int j = 1; j <= a; j++) {
> diamond += "*";
> }
> diamond += "\n";
> }
> JOptionPane.showMessageDialog(null, diamond);
> System.out.println(diamond);
> }
> public static void main(String args[]) {
> String strSize;
> // Get the size of the diamond to draw
> strSize = JOptionPane.showInputDialog(null, "Enter diamond size:");
> int size = Integer.parseInt(strSize);
This code tries to convert the input into an integer, but this is
not in a try/catch block, so your new catch-Block for the
NumberFormatException
is not executed.
You have to move this in the try-Block.
> // Assert that the value entered is greater than 0, otherwise,
> // it will generate AssertionError exception.
> try {
> assert(size > 0);
> printDiamond(size);
> } catch (AssertionError e) {
> JOptionPane.showMessageDialog(null, "AssertionError is captured:
> " +
> "Size should be > 0.");
> }
> catch (NumberFormatException e) {
> JOptionPane.showMessageDialog(null, "Input should be numeric. ");
> }
> System.exit(0);
> }
> }
HTH
Ewald
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