why am I keep getting a FileNotFoundException?

Question

I don't understand why I keep getting a FileNotFoundException? I am using java through Eclipse and am trying to read a file.txt of integers and I want to add them together to test them but keep getting the exception.

I have imported the file into eclipse. Here is my code and the exception messages I am getting.

    public class FileRead {
    //fields
    private Scanner s;
    private int[] arr;
    /**
     * @throws FileNotFoundException 
     * 
     */
    public FileRead() throws FileNotFoundException{
        s = new Scanner(new File("lab1_data.txt"));
        arr = new int[10000000];
        for(int i = 0;i < arr.length;i++){
            arr[i] = s.nextInt();
        }

    }

    public int addArr(){
        int a = 0;
        for(int x: arr){
            a = a + x;
        }
        return a;
    }

    /**
     * @param args
     */
    public static void main(String[] args) {
        FileRead r = null;
        try {
            r = new FileRead();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        r.addArr();
    }

}

java.io.FileNotFoundException: lab1_data.txt (The system cannot find the 
file specified)
at java.io.FileInputStream.open0(Native Method)
at java.io.FileInputStream.open(Unknown Source)
at java.io.FileInputStream.<init>(Unknown Source)
at java.util.Scanner.<init>(Unknown Source)
at FileRead.<init>(FileRead.java:22)
at FileRead.main(FileRead.java:44)
Exception in thread "main" java.lang.NullPointerException
at FileRead.main(FileRead.java:48)

Answer 1

(new File("lab1_data.txt"));

传递确切的目录路径/文件夹名称/lab1_data.txt

Answer 2

lab1_data.txt should be in classpath to be found. Better appraoach to read the files is getResourceAsStream . A simple google search should help.

Answer 3

check where the file exists and add a full path to the file at new File("...") .

be aware that the current project path not always the same path where your .java files are.

Answer 4

This Code Works

        String path="";
        File f=new File("lab1_data.txt");
        path=f.getAbsolutePath();