堆栈问题，不存储值

Question

I have written a browser for a side project, currently I have this code:

ReadHTML is my constructor, and load web page is the method I use to load a web page, what should happen, is when the user presses back, it should trigger the action listener and then check if the stack has some content, however, I have tested this and found that the code will reach the action listener and the stack test will fail, leading me to believe that my program is not storing content into the stack, I would appreciate if someone could point out where I am going wrong, or a better way of doing this I would be most appreciative.

If you don't have enough code, or need me to add more information, I can edit and post pretty quickly, thanks in advance!

Stack<String> backStack = new Stack<String>();
Stack<String> forwardStack = new Stack<String>();
boolean stackTest = false;

    private void loadWebPage(String userInput) {
    if (stackTest = true) {
        forwardStack.push(urlBox.getText());
        stackTest = false;
    } else {
        backStack.push(urlBox.getText());
    }
    try {
        webWindow.setPage(userInput);
        urlBox.setText(userInput);
    } catch (Exception e) {
        try {
            File file = new File(userInput);
            webWindow.setPage(file.toURI().toURL());
        } catch (MalformedURLException e1) {
            e1.printStackTrace();
        } catch (IOException e1) {
            e1.printStackTrace();
        }
    }
}
public ReadHTML() {
        forward.addActionListener(
    new ActionListener() {
        public void actionPerformed(ActionEvent forwardPress) {
            if (!forwardStack.empty()) {
                loadWebPage(forwardStack.pop());
            }
        }
    });
    back.addActionListener(
    new ActionListener() {
        public void actionPerformed(ActionEvent backPress) {
            if (!backStack.empty()) {
                stackTest = true;
                loadWebPage(backStack.pop());
            }
        }
    });
}

Answer 1

It looks like

 if (stackTest = true) {

Should be

 if (stackTest == true) {