编写一个Java程序，计算一下1,2,…,9这9个数字可以组成多少个互不相同的、无重复数字的三位偶数。

package a;

public class SanWeiOuShu {

    public static void main(String[] args) {
         String str="123456789";
         String a,b,c;
         int sum=0;
         for (int i = 1; i < 9; i+=2) {
            a=str.substring(i,i+1);
            String str1 = str.replace(a,"");            
            
            for (int j = 0; j < 8; j++) {                    
                b=str1.substring(j,j+1);    
                String str2 = str1.replace(b, "");
                
                for (int k = 0; k < 7; k++) {                                
                    c=str2.substring(k,k+1);                        
                    System.out.print(new Integer(c+b+a)+"\t");                
                    sum+=1;
                }            
                System.out.println();
            }
            System.out.println();
        }
                  System.out.println("总个数为："+sum);
    }

}