Android File Compare diff(File f1, File f2)

Description

diff

License

Open Source License

Declaration

public static boolean diff(File f1, File f2) throws IOException 

Method Source Code

//package com.java2s;
/*/*from   w  w  w.ja v a2  s  . com*/
 * Copyright (c) 2015. Philip DeCamp
 * Released under the BSD 2-Clause License
 * http://opensource.org/licenses/BSD-2-Clause
 */

import java.io.*;
import java.nio.ByteBuffer;

public class Main {
    public static boolean diff(File f1, File f2) throws IOException {
        if (f1 != null && !f1.exists())
            f1 = null;

        if (f2 != null && !f2.exists())
            f2 = null;

        if (f1 == f2 || f1 != null && f1.equals(f2))
            return false;

        if (f1 == null)
            return f2 != null && f2.length() != 0;

        if (f2 == null)
            return f1 != null && f1.length() != 0;

        long len = f1.length();

        if (len != f2.length())
            return true;

        DataInputStream s1 = new DataInputStream(new BufferedInputStream(
                new FileInputStream(f1)));
        DataInputStream s2 = new DataInputStream(new BufferedInputStream(
                new FileInputStream(f2)));

        long p = 0;

        for (; p < len - 7; p += 8) {
            if (s1.readLong() != s2.readLong())
                return true;
        }

        for (; p < len; p++) {
            if (s1.read() != s2.read())
                return true;
        }

        s1.close();
        s2.close();
        return false;
    }

    public static boolean diff(File f1, ByteBuffer b2) throws IOException {
        if (f1 != null && !f1.exists())
            f1 = null;

        if (b2 != null)
            b2 = b2.slice();

        if (f1 == null)
            return b2 != null && b2.remaining() != 0;

        if (b2 == null)
            return f1 != null && f1.length() != 0;

        if (f1.length() != b2.remaining())
            return true;

        DataInputStream s1 = new DataInputStream(new BufferedInputStream(
                new FileInputStream(f1)));
        final int len = b2.capacity();
        int p = 0;

        for (; p < len - 7; p += 8) {
            if (s1.readLong() != b2.getLong())
                return true;
        }

        for (; p < len; p++) {
            if (s1.read() != (b2.get() & 0xFF))
                return true;
        }

        s1.close();
        return false;
    }

    public static boolean diff(ByteBuffer b1, ByteBuffer b2)
            throws IOException {
        if (b1 == b2 || b1 != null && b1.equals(b2))
            return false;

        if (b1 == null)
            return b2 != null && b2.remaining() != 0;

        if (b2 == null)
            return b1 != null && b1.remaining() != 0;

        b1 = b1.slice();
        b2 = b2.slice();

        int len = b1.capacity();
        if (len != b2.capacity())
            return true;

        int p = 0;

        for (; p < len - 7; p += 8)
            if (b1.getLong() != b2.getLong())
                return true;

        for (; p < len; p++)
            if (b1.get() != b2.get())
                return true;

        return false;
    }
}

Related

1. compareContents(File file1, File file2)