im getting error and i cant understand whats wrong with it pls check n tell me

Question

import java.io.*;
import java.math.*;
class simcolum
{
public static void main(String [] args) throws IOException
{
String plaintext,ciphertext="",temp="";
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
int i=0,j=0;
System.out.print("Enter plain text:");
plaintext=br.readLine();
int plen=plaintext.length();
for(i=0;i<plen;++i)
{
if(plaintext.charAt(i)!=' ')
temp+=plaintext.charAt(i);
}
System.out.println("temp= "+temp);
int len=temp.length();
System.out.print("Enter no. of columns(max."+len+"):");
int cols=Integer.parseInt(br.readLine());
if(cols<=len)
{
int rows=1,k=0;
if(len%cols==0)
rows=len/cols;
else
rows=(len/cols)+1;
char matrix[][]=new char[rows][cols];
for(i=0;i<rows;i++)
{
for(j=0;(j<cols)&&(k<len);++j)
{
matrix[i][j]=temp.charAt(k);
k++;
}
}
i--;
for(;j<cols;j++)
matrix[i][j]='

Answer 1

What does the error message say?