diff -r 8ddf4af937d7 -r 5bab2e971333 src/de/uapcore/sudoku/DocumentHandler.java
--- a/src/de/uapcore/sudoku/DocumentHandler.java	Sat Jan 26 19:34:31 2013 +0100
+++ b/src/de/uapcore/sudoku/DocumentHandler.java	Sun Jan 27 15:03:57 2013 +0100
@@ -26,10 +26,15 @@
 
 package de.uapcore.sudoku;
 
+import java.io.BufferedReader;
 import java.io.BufferedWriter;
+import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
+import java.io.InputStreamReader;
 import java.io.OutputStreamWriter;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 /**
  *
@@ -43,7 +48,34 @@
         if (!isFilenameSet()) {
             throw new IOException("no filename supplied");
         }
-        // TODO: implement
+        int row = 0;
+        try (BufferedReader in = new BufferedReader(
+                new InputStreamReader(new FileInputStream(filename)))) {
+            Pattern pat = Pattern.compile("^\\s*(?:[1-9_] ){8}[1-9_]\\s*$");
+            String line;
+            while ((line = in.readLine()) != null) {
+                if (line.matches("^\\s*$")) {
+                    continue;
+                }
+                Matcher m = pat.matcher(line);
+                if (m.matches()) {
+                    String c[] = line.trim().split(" ");
+                    if (c.length != 9) {
+                        break;
+                    }
+                    for (int i = 0 ; i < 9 ; i++) {
+                        field.setCellValue(i, row,
+                                c[i].equals("_") ? 0 : Integer.valueOf(c[i]));
+                    }
+                    row++;
+                } else {
+                    break;
+                }
+            }
+            if (row != 9) {
+                throw new IOException("Kein Sudoku-Feld enthalten!");
+            }
+        }
     }
     
     public void save(Field field) throws IOException {