Android: 'getWindowManager()' method error and solution

The method 'getWindowManager()' is a method of the 'android.view.Window' class, not the 'android.app.Activity' class. To access the 'getWindowManager()' method, you need to get a reference to the current window of the activity using the 'getWindow()' method and then call the 'getWindowManager()' method on the window object.

Here's an example of how to use 'getWindowManager()' in an activity:

public class MyActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        // Get a reference to the window
        Window window = getWindow();
        
        // Get the WindowManager from the window
        WindowManager windowManager = window.getWindowManager();
        
        // Use the WindowManager to perform operations on the window
        // For example, get the display metrics:
        DisplayMetrics metrics = new DisplayMetrics();
        windowManager.getDefaultDisplay().getMetrics(metrics);
    }
}