Lint Warning for using != to compare a string

Android Programming (3rd Edition) 26. Loopers, Handlers, and HandlerThread
1

The following code gives me a Lint warning (the yellow highlight with a suggestion for alternate code) on the “!=” stating basically that strings should be compared with .equals() instead of == or !=. When I modified the code to “!mRequestMap.get(target).equals(url)” I started getting some random fatal errors saying that it was attempting to invoke a method on a null object. It seems to run fine using the ==, but I’m assuming this has to do with capital and lowercase letters having different values and == not capturing that. Is there a different way I should convert this comparison, or just not worry about it?

mResponseHandler.post(new Runnable() {
            @Override
            public void run() {
                if (mRequestMap.get(target) != url || mHasQuit) {
                    return;
                }

                mRequestMap.remove(target);
                mTThumbnailDownloadListener.onThumbnailDownloaded(target, bitmap);
            }
        });
2

You can change one line to:
if ((mRequestMap.get(target) != null) && (!mRequestMap.get(target).equals(url) || mHasQuit)) {
As far as I understand this is a better way to compare Strings and Objects at all.
And check this: There are some bugs!

3

I use

    if (!Objects.equals(mRequestMap.get(targetView), url) || mHasQuit) {
        return;
    }

The static equals method of class Objects will help you check the null issue first.

    public static boolean equals(Object a, Object b) {
        return (a == b) || (a != null && a.equals(b));
    }