Java/ read from .txt file

Question

I have .txt file, and I want to read from it to char array.

I have problem, in the .txt file I have:

1  a

3  b

2  c

which mean that a[1]='a', a[3]='b', a[2]='c'.

How in reading the file, I ignore from spaces, and consider the new lines? Thanks

Answer 1

I would suggest you to use a Map for this instead since it's better suited for this kind of problems.:

public static void main(String[] args) {

    Scanner s = new Scanner("1 a 3 b 2 c"); // or new File(...)

    TreeMap<Integer, Character> map = new TreeMap<Integer, Character>();

    while (s.hasNextInt())
        map.put(s.nextInt(), s.next().charAt(0));
}

---

If you would like to convert the TreeMap to char[] you can do the following:

char[] a = new char[map.lastKey() + 1];

for (Entry<Integer, Character> entry : map.entrySet())
    a[entry.getKey()] = entry.getValue();

Notes:

• This solution does not work with negative indexes
• Takes only the "first" character if more than one

Answer 2

It's probably easiest to use a Scanner .

ArrayList<String> a = new ArrayList<String>();
Scanner s = new Scanner(yourFile);
while(s.hasNextInt()) {
    int i = s.nextInt();
    String n = s.next();
    a.add(n);
}

Of course, this boldly assumes correct input; you should be more paranoid. If you need to deal with each line specially, you can use hasNextLine() and nextLine() , and then split the line using split() from the String class.