Setup Java Look and Feel on IntelliJ IDEA GUI Forms

This involves 2 main steps.

Step 1: Create method to set Look & Feel of your preferences. 

We use 'Nimbus' Look & Feel for this example.

private void initLookandFeel(){

try {
    for (LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
        if ("Nimbus".equals(info.getName())) {
            UIManager.setLookAndFeel(info.getClassName());
            break;
        }
    }
} catch (Exception e) {
    // If Nimbus is not available, you can set the GUI to another look and feel.
}

}

Step 2: Setup and update the UI for new Look & Feel after all components have been initiated

When you have the class extended to JFrame class, do the following.

// constructor
public MyClass(){

   // IntelliJ IDEA GUI form components binding and initiation
   // to the given top panel name: 'mainPanel'
   setContentPane(mainPanel);

   // setting up Look and Feel and update UI
   initLookandFeel();
   SwingUtilities.updateComponentTreeUI(this)
}

If you are not sure how to get the IntelliJ IDEA forms be run, check here.