java.lang.NumberFormatException: For input string: "1"

Question

"out.txt" content is

1

My JAVA code is like this.

    int val=0;
    BufferedReader br = new BufferedReader(new FileReader("out.txt"));

    while(true) {
        String line = br.readLine();
        if (line==null) break;
        val=Integer.parseInt(line);
    }
    br.close();

and debugger says,

java.lang.NumberFormatException: For input string: "1"

i need to use 1 from "out.txt". How can i use 1 as Integer? Thank you for your attention :)

Answer 1

You must be having the trailing whitespaces. Use the trim() function as follows:

val = Integer.parseInt(line.trim());

Here is the code snippet:

int val = 0;
BufferedReader br = new BufferedReader(new FileReader("out.txt"));

String line = null;
while(true) {
    line = br.readLine();
    if (line == null) break;
    val = Integer.parseInt(line.trim());
}
br.close();

Also, if you want to check whether String is null or empty you can start using the Apache Commons StringUtils as follows:

if (StringUtils.isEmpty(line)) break;