Java brainfuck interpreter

gistfile1.txt

package ca.deamon.dais.brainfuck;

import java.util.Arrays;
import java.util.Scanner;

public class BrainFuckInterpreter {
  byte[] dat;
	char[] program;
	
	int counter = 0;
	int ptr = 0;
	
	Scanner in;
	
	public BrainFuckInterpreter(char[] program) {
		dat = new byte[30000];
		Arrays.fill(dat, (byte)0);
		this.program = program;
		in = new Scanner(System.in);
	}
	
	public void interpret() {
		while(counter < program.length) {
			interpret(program[counter]);
			counter++;
		}
	}
	
	private void interpret(char c) {
		if(c == '>') {
			ptr++;
		}
		if(c == '<' && ptr > 0) {
			ptr--;
		}
		if(c == '+') {
			dat[ptr]++;
		}
		if(c == '-') {
			dat[ptr]--;
		}
		if(c == '.') {
			System.out.print((char)dat[ptr]);
		}
		if(c == ',') {
			while(!in.hasNext());
			dat[ptr] = in.nextByte();
		}
		if(c == '[') {
			if(dat[ptr]==0) {
				int n = 1;
				counter++;
				while(n > 0 && counter < program.length) {
					if(program[counter] == '[') n++;
					if(program[counter] == ']') n--;
					counter++;
				}
			}
		}
		if(c == ']') {
			if(dat[ptr]!=0) {
				int n = 1;
				counter--;
				while(n > 0 && counter < program.length) {
					if(program[counter] == '[') n--;
					if(program[counter] == ']') n++;
					counter--;
				}
				counter++;
			}
		}
	}
}