package bogush;

import java.io.*;
import java.nio.file.Path;

class LineCounter {
    static int count(Path file) throws IOException {
        try (InputStream is = new BufferedInputStream(new FileInputStream(file.toFile()))) {
            boolean empty = true;
            byte bytes[] = new byte[1024];
            int readChars;
            int count = 1;
            while ((readChars = is.read(bytes)) != -1) {
                empty = false;
                for (int i = 0; i < readChars; ++i) {
                    if (bytes[i] == '\n') {
                        ++count;
                    }
                }
            }
            if (empty) {
                return 0;
            } else {
                return count;
            }
        }
    }
}

package bogush;

import java.io.*;
import java.nio.file.Path;

class LineCounter {
    static int count(Path file) throws IOException {
        try (InputStream is = new BufferedInputStream(new FileInputStream(file.toFile()))) {
            boolean empty = true;
            byte bytes[] = new byte[1024];
            int readChars;
            int count = 0;
            while ((readChars = is.read(bytes)) != -1) {
                empty = false;
                for (int i = 0; i < readChars; ++i) {
                    if (bytes[i] == '\n') {
                        ++count;
                    }
                }
            }
            return (count == 0 && !empty) ? 1 : count;
        }
    }
}

--- 
+++ 
@@ -9,7 +9,7 @@
             boolean empty = true;
             byte bytes[] = new byte[1024];
             int readChars;
-            int count = 0;
+            int count = 1;
             while ((readChars = is.read(bytes)) != -1) {
                 empty = false;
                 for (int i = 0; i < readChars; ++i) {
@@ -18,7 +18,11 @@
                     }
                 }
             }
-            return (count == 0 && !empty) ? 1 : count;
+            if (empty) {
+                return 0;
+            } else {
+                return count;
+            }
         }
     }
 }
Fix to count 0 on empty files and (amount of line-breaks + 1) on non-empty files
