Trying to determine the last occurence of a number within a word string.

Question

Hi All,
I am trying to find the last occurence of a number within a string. I have had a quick look at the Java Tutorial and know about lastIndexOf and substring. The thing is I have to test for the existance of the numbers 0-9 within a product code that typically looks like this:
s1_14G12B
s1_17G1BA
s2_24GD
The only part of the above strings that I am interested in is the letter(s) that follow the very last number, so in the case of those codes presented above, I would like to extract the following:
B
BA
D
I have written some code that performs a similar operation:
public class FindPriceCode
  private String priceCode;
  private String[] numberValues = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9"};
  public FindPriceCode()
    priceCode = "s2_71G4BA";
    for(int i=0; i<numberValues.length; i++)
      int location = priceCode.lastIndexOf(numberValues);
System.out.println("Character " + numberValues[i] + " found at position: " + location);
public static void main(String[] args)
FindPriceCode myPriceCode = new FindPriceCode();
...finding the location of numberValues string within the given example code. I am now at a loss as to how I can determine the location of the last number occurence (moving right to left) and then build a substring from that number. Any help will be greatly appreicated.
Thanks
David

Answer 1

Hello,
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class CutNumberTest extends JFrame implements ActionListener {
     private JTextField input= new JTextField(10);
     private JTextArea result=new JTextArea(10,10);
     char[]numbers=new char[]{'0','1','2','3','4','5','6','7','8','9'};
     public CutNumberTest() {
          super("CutNumberTest");
          setDefaultCloseOperation(DISPOSE_ON_CLOSE);
          JButton cutButton = new JButton("cut number");
          cutButton.addActionListener(this);
          JPanel topPanel=new JPanel();
          JLabel label=new JLabel("Please enter price-code:");
          topPanel.add(label);
          topPanel.add(input);
          topPanel.add(cutButton);
          getContentPane().add(topPanel, BorderLayout.NORTH);
          getContentPane().add(new JScrollPane(result));
          pack();
          setLocationRelativeTo(null);
     public void actionPerformed(ActionEvent e) {
          char[] code=input.getText().toCharArray();          
          int counter=code.length;
          boolean lastNumFound=false;
          while(!lastNumFound && --counter >= 0)
               lastNumFound=isNumber(code[counter]);
          result.append(lastNumFound ? "result: "+input.getText().substring(counter+1)+"\n" : "No number found!\n");
     private boolean isNumber(char chr){
          boolean isNumber=false;
          int counter=-1;
          while(++counter < numbers.length && !isNumber)
               isNumber=numbers[counter]==chr;
          return isNumber;
     public static void main(String[] args) {
          new CutNumberTest().setVisible(true);
}//copy/paste:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class CutNumberTest extends JFrame implements ActionListener {
     private JTextField input= new JTextField(10);
     private JTextArea result=new JTextArea(10,10);
     char[]numbers=new char[]{'0','1','2','3','4','5','6','7','8','9'};
     public CutNumberTest() {
          super("CutNumberTest");
          setDefaultCloseOperation(DISPOSE_ON_CLOSE);
          JButton cutButton = new JButton("cut number");
          cutButton.addActionListener(this);
          JPanel topPanel=new JPanel();
          JLabel label=new JLabel("Please enter price-code:");
          topPanel.add(label);
          topPanel.add(input);
          topPanel.add(cutButton);
          getContentPane().add(topPanel, BorderLayout.NORTH);
          getContentPane().add(new JScrollPane(result));
          pack();
          setLocationRelativeTo(null);
     public void actionPerformed(ActionEvent e) {
          char[] code=input.getText().toCharArray();          
          int counter=code.length;
          boolean lastNumFound=false;
          while(!lastNumFound && --counter >= 0)
               lastNumFound=isNumber(code[counter]);
          result.append(lastNumFound ? "result: "+input.getText().substring(counter+1)+"\n" : "No number found!\n");
     private boolean isNumber(char chr){
          boolean isNumber=false;
          int counter=-1;
          while(++counter < numbers.length && !isNumber)
               isNumber=numbers[counter]==chr;
          return isNumber;
     public static void main(String[] args) {
          new CutNumberTest().setVisible(true);
Regards,
Tim