How to resolve NumberFormatException : for input string error?

[joseplta5]

This is a part of my code, where Im trying to generate a few patterns, Now Im getting an error saying :
Exception in thread "main" java.lang.Numbe rFormatExceptio n: For input string: "C2"
at java.lang.Numbe rFormatExceptio n.forInputStrin g(NumberFormatE xception.java:4 8)
at java.lang.Integ er.parseInt(Int eger.java:449)
at java.lang.Integ er.valueOf(Inte ger.java:554)
at nprf.offline.Pa tternGenerator. doGeneratePatte rn(PatternGener ator.java:77)
at nprf.offline.Pa tternGenerator. main(PatternGen erator.java:23)

The error is occuring in these two lines [edit: 50 and 51] as shown below:
int a= Integer.valueOf (Fe[i][k].substring(1,Fe[i][k].indexOf(','))) ;
int b= Integer.valueOf (Fe[j][k].substring(1,Fe[j][k].indexOf(','))) ;

Fe[][] is an array which is declared as String [][] Fe=new String[500][77];

public void doGeneratePattern() throws Exception 
    {
        String sql; 
        ResultSet rs;
             
        // STEP NO 8
        int i=0;
        int ptr=0;
      
        findF1();
      
        //STEP NO 10
        e=2;
        while (true) 
        {
            // Flush support of size MAX_CA
            for(int a=0;a<MAX_CA;a++)
                Support[a]=0;
           
            // Flush  CAe
            for(int a=0;a<MAX_CA;a++)
                for(int b=0;b<Auxiliary.MAX_ITERATION;b++) 
                    CAe[a][b]=null;
                          
            ptr=0;
            int j;
            for (i=0;i<nFe;i++) 
            {
                for (j=i+1;j<nFe;j++) 
                {
                    boolean flag=false;
                    for (int k=0;k<e-2;k++) 
                    {
                        if (Fe[i][k].equals(Fe[j][k]))
                            continue;
                        else 
                        {
                            flag=true;
                            break;
                        }
                    }
                    int k;
                    if (flag==false) // (k-2) items matched
                    {
                        for (k=0;k<e-2;k++)
                            CAe[ptr][k]=Fe[i][k];

                     //   Double a=  Double.parseDouble(Fe[i][k].substring(1,Fe[i][k].indexOf(',')));
                     //   Double b=  Double.parseDouble(Fe[j][k].substring(1,Fe[j][k].indexOf(',')));
                       int a=  Integer.valueOf(Fe[i][k].substring(1,Fe[i][k].indexOf(',')));
                       int b=  Integer.valueOf(Fe[j][k].substring(1,Fe[j][k].indexOf(',')));
                    //  System.out.println("value of a and b"+a +b);
                        if(e!=2 || a==1)
                            if (a<b)
                            {
                                CAe[ptr][k]=Fe[i][k];
                                CAe[ptr][k+1]=Fe[j][k];
                                ptr++;
                            }
                    }
                    else
                        continue;
                }
            }
            nCAe=ptr;
            for (int k=0;k<nCAe;k++) 
            {
                sql="select * from navigationtransaction";
                rs=Auxiliary.stmt.executeQuery(sql);
                while (rs.next()) 
                {
                    String itemString=rs.getString(2);
                    boolean flag=false;
                    for(int l=0;l<e;l++)
                    {
                        if(itemString.contains(CAe[k][l])==true) 
                            continue;
                        else 
                            flag=true;
                    }
                    if(flag==false)
                        Support[k]++;
                }
            }
            int m=0;
            for (int k=0;k<nCAe;k++) 
            {
                if (Support[k]>=Auxiliary.minSupport) 
                {
                    for (j=0;j<e;j++)
                        Fe[m][j]=CAe[k][j];
                    m++;
                }
            }
            nFe=m;
            for (int k=0;k<nFe;k++) 
            {
                for (j=0;j<e;j++) 
                    NP[nNP][j]=Fe[k][j];
                nNP++;
            }
            e=e+1;      
            if(nFe==0) 
                break;
        }      
    }

[Rabbit]

The substring you're returning includes the comma.