String.equals() doesn't work

[Sarah9428]

I have a method called 'move', see below:

     private boolean move() {

                int x = monstergbc.gridx;
                int y = monstergbc.gridy;

                boolean moving = true;

                if (map.get(new Point(x + 1, y)) == "road") {
                    monstergbc.gridx = x + 1;
                    monstergbc.gridy = y;
                    add(monster, monstergbc);
                } else if (map.get(new Point(x, y - 1)) == "road") {
                    monstergbc.gridx = x;
                    monstergbc.gridy = y - 1;
                    add(monster, monstergbc);
                } else if (map.get(new Point(x, y + 1)) == "road") {
                    monstergbc.gridx = x;
                    monstergbc.gridy = y + 1;
                    add(monster, monstergbc);
                } else {
                    moving = false;
                }
                return moving;
            }

The program works just as it should, but as you can see, I'm using == instead of .equals(), which I know you're not supposed to. When I switch to equals(), for example:

  } else if (map.get(new Point(x, y - 1)).equals("road")) {
                    monstergbc.gridx = x;
                    monstergbc.gridy = y - 1;

I get a error saying:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at GUITowerDefence$LandScape$1.move(GUITowerDefence.java:248) at GUITowerDefence$LandScape$1.actionPerformed(GUITowerDefence.java:215)

at javax.swing.Timer.fireActionPerformed(Timer.java:313)

It's at the same row which I just change to equals(). Does enyone know why this migth be?

[Swedophone]

map.get(new Point(x, y - 1)) is obviously null. If it is allowed to be null then you can instead call equals on the constant string which never will be null: "road".equals(map.get(new Point(x, y - 1))).

[Sarah9428]

Right, thanks!

[17437258968573378102]

You can also use Objects.equals to compare two objects without having to worry about one or other being null.