CheckBalanced3.java

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

public class CheckBalanced3 {

    /**
    *   Program: CheckBalanced3.java
    *   Purpose: Read a Java source code file and check it has balanced brackets {}()[].
    *       Do not include brackets within quotes or comments.
    *   Version: More efficient - reads file once, uses arraylist.
    *   Creator: Chris Clarke
    *   Created: 13.11.2015
    */

    // create array list
    private static ArrayList<String> lines = new ArrayList<String>();

    // create linked list object as instance variable
    LinkedList<Integer> list = new LinkedList<Integer>();

    // initialise top (of stack)
    static int top = -1;

    public void push(int t) {
        list.add(new Integer(t));
    } // push()

    public int pop() {
        if (top != -1)
            return list.remove(top);
        return top;
    } // pop()

    public static String doBalanceCheck(char ch0, char ch1, CheckBalanced3 stack, String javaSource,
     boolean readFile) {
        File f;
        Scanner scan = null;
        String line;
        String result = "";
        char ch;
        int lineNum = 0;
        int openLineNum = 0;
        int position = 0;
        top = -1;
        boolean inSingleQuotes = false;
        boolean inDoubleQuotes = false;
        boolean inMultiLineComment = false;

        if (readFile) {
            try {
                f = new File(javaSource);
                scan = new Scanner(f);
            } catch (IOException e) {
                System.out.println("Caught IOException");
                System.exit(1);
            } // try

            while (scan.hasNextLine()) {
                line = scan.nextLine();
                lines.add(line);
            } // while

            if (scan!=null) scan.close();
        } // if

        for (String ln: lines) {
            for (int i=0; i<ln.length(); i++) {
                ch = ln.charAt(i);
                if (ch=='\"') {
                    inDoubleQuotes = !inDoubleQuotes;
                } else if (ch=='\'') {
                    inSingleQuotes = !inSingleQuotes;
                } else if (ch=='/' && i<ln.length()-1) {
                    if (ln.charAt(i+1)=='/') {
                        break; // single line comment - ignore rest of line
                    } else if (ln.charAt(i+1)=='*') {
                        inMultiLineComment = true;
                    } // if ln
                } else if (ch=='*' && i<ln.length()-1) {
                    if (ln.charAt(i+1)=='/') {
                        inMultiLineComment = false;
                    } // if ln
                } // if ch
                if (!inDoubleQuotes && !inSingleQuotes && !inMultiLineComment) {
                    if (ch==ch0) {
                        stack.push(++top);
                        openLineNum = lineNum;
                        position = i;
                    } // if ch
                    if (ch==ch1) {
                        stack.pop();
                        top--;
                    } // if ch
                } // if !in
            } // for i
            lineNum++;
        } // for ln

        if (top == -1)
            result = ""+ch0+ch1+": BALANCED";
        else
            result = ""+ch0+ch1+": NOT BALANCED at line"
            +(openLineNum+1)+", position "+(position+1);

        return result;
    } // doBalanceCheck()

    public static void main(String[] args) {
        CheckBalanced3 myStack = new CheckBalanced3();
        if (args.length==0) {
            System.out.println("Usage: java CheckBalanced3 \"MyProgram.java\"");
        } else {
            System.out.println (doBalanceCheck('{', '}', myStack, args[0], true));
            System.out.println (doBalanceCheck('(', ')', myStack, args[0], false));
            System.out.println (doBalanceCheck('[', ']', myStack, args[0], false));
        } // if
    } // main()

} // class CheckBalanced3