Question

Here I’m reading text file which contains a integer in each line and I’m printing all the integers which appeared more than once.

As you can see I used Hash Map and I assigned integers as Key and number of occurrence of number as value.

Here I’m getting Number Format Exception here. Can anyone help me with this?

package fileread;

import java.io.*;
import java.util.HashMap;


public class Main {


public static void main(String[] args) {
    // TODO code application logic here
    HashMap<Integer, Integer> lines = new HashMap<Integer, Integer>();
    try {
        FileInputStream fstream = new FileInputStream("C:/Users/kiran/Desktop/text.txt");
        DataInputStream in = new DataInputStream(fstream);
        BufferedReader br = new BufferedReader(new InputStreamReader(in));
        String str;

        while ((str = br.readLine()) != null) {

            Integer intObj = Integer.valueOf(str);
            if (lines.containsKey(intObj)) {
                int x = 0;
                x = lines.get(intObj);
                if (x == 2) {
                    System.out.println(intObj);
                }
                lines.put(intObj, x++);

            } else {

                lines.put(intObj, 1);
            }
        }
        in.close();
    } catch (Exception e) {
        System.err.println(e);
    }
}
}

Answer 1

It’s very likely that your number format exception is happening at this line:

            Integer intObj = Integer.valueOf(str);

See the documentation for Integer.valueOf here

I’d guess this is because one of the lines is not an integer