the undo button works

src/backend/Board.java

@@ -157,7 +157,8 @@ public class Board {
 		}
 		else {
 			outputString+= "1";
-		}
+		}
+		outputString += "\n";
 		return outputString;
 	}
 	
@@ -382,6 +383,15 @@ public class Board {
 		else {
 			enPassant = true;
 		}
+		enPassant = false;
+		kingWMoved = false;
+		kingBMoved = false;
+		rookLWMoved = false;
+		rookRWMoved = false;
+		rookLBMoved = false;
+		rookRBMoved = false;
+		castling = false;
+		castlingDone = false;
 	}
 	
 	/* The following methods require more work ! */
@@ -753,8 +763,64 @@ public class Board {
 	}
 
 	public void undoLastMove() {
-		//TODO
-		
+		if(turnNumber == 0) {
+			String lastBoard = previousBoard.get(turnNumber); // we have a String but we need a String[] in order to use the constructer
+			String[] oldBoard = new String[10];
+			boolean complete = false;
+			int indexLine=0;
+			int indexColumn=0;
+			for(int i=0; i<10; i++) {
+				oldBoard[i] = "";
+			}
+			while (complete == false) {
+				if (lastBoard.charAt(indexColumn) == '\n') {
+					indexLine+=1;
+					if (indexLine == 10) {
+						complete= true;
+					}
+				}
+				else {
+					oldBoard[indexLine] += lastBoard.charAt(indexColumn);
+				}
+				indexColumn+=1;
+			}
+			Board undo = new Board(oldBoard);
+			this.pieces = undo.pieces;
+			this.xTwo=undo.xTwo;
+			this.yTwo=undo.yTwo;
+			this.enPassant=undo.enPassant;
+			this.lastTurnPawnTwo=undo.lastTurnPawnTwo;
+		}
+		if (turnNumber != 0 ) {
+			turnNumber -= 1;
+			String lastBoard = previousBoard.get(turnNumber); // we have a String but we need a String[] in order to use the constructer
+			String[] oldBoard = new String[10];
+			boolean complete = false;
+			int indexLine=0;
+			int indexColumn=0;
+			for(int i=0; i<10; i++) {
+				oldBoard[i] = "";
+			}
+			while (complete == false) {
+				if (lastBoard.charAt(indexColumn) == '\n') {
+					indexLine+=1;
+				if (indexLine == 10) {
+					complete= true;
+					}
+				}
+				else {
+					oldBoard[indexLine] += lastBoard.charAt(indexColumn);
+				}
+				indexColumn+=1;
+			}
+			Board undo = new Board(oldBoard);
+			this.pieces = undo.pieces;
+			this.xTwo=undo.xTwo;
+			this.yTwo=undo.yTwo;
+			this.enPassant=undo.enPassant;
+			this.lastTurnPawnTwo=undo.lastTurnPawnTwo;
+			previousBoard.remove(turnNumber+1);
+		}
 		
 	}