File I/O in Java

Question

I have problems with the code for my own Vector class.

FIXED. Added reading and writing to file, but this try/catch things look too cumbersome for me. Maybe there's a better way of file I/O?

FIXED-2 Oh, I've just discovered "throws" and now my code looks really good. Thanks everyone for help! Here's the final version of Stack.java:

import java.util.Scanner;
import java.io.*;

class Vector {

        private int[] vec;
        private int length, pointer;

        public Vector(int n) {
            pointer = 0;
            length = n;
            vec = new int[length];
        }

        public int get(int i) {
            return vec[i];
        }
        public void set(int i, int n) {
            vec[i] = n;
        }

        public void push(int n) {
            if (pointer == length) {
                int[] nvec = new int[length*2];
                for (int i = 0; i < length; i++)
                    nvec[i] = vec[i];
                length *= 2;
                vec = null;
                vec = nvec;
            }
            vec[pointer++] = n;
        }

        public void delete() {
            pointer--;
            if (pointer == length / 4) {
                int[] nvec = new int[length/2];
                for (int i = 0; i <= pointer; i++)
                    nvec[i] = vec[i];
                length /= 2;
                vec = null;
                vec = nvec;
            }
        }

        public int size() {
            return pointer;
        }
        public int actualSize() {
            return length;
        }
    }

public class Stack {

    public static void main(String[] args) throws IOException {

        File ifile = new File("stack1.in");
        BufferedReader reader = new BufferedReader(new FileReader(ifile));

        File ofile = new File("stack1.out");
        BufferedWriter writer = new BufferedWriter(new FileWriter(ofile));

        int n = Integer.parseInt(reader.readLine());

        Vector stack = new Vector(10);
        for (int i = 0; i < n; i++) {
            String s = reader.readLine();
            if (s.charAt(0) == '-') {
                writer.write(Integer.toString(stack.get(stack.size()-1)));
                writer.write("\n");
                stack.delete();
            } else {
                s = s.substring(2);
                stack.push(Integer.parseInt(s));
            }
        }

        writer.close();
        reader.close();
    }
}

Answer 1

Vector stack = new Vector(10);

Answer 2

Initialise the Vector class as below

 Vector stack = new Vector(10);

Answer 3

Your syntax is wrong. Perhaps you meant something like this:

Vector stack = new Vector(10);

Also, are you sure you want your Vector class inside your Stack class? Also also, it's generally a bad idea to name your classes the same thing as existing Java classes.