NotificationSample.java

import com.intellij.notification.Notification;
import com.intellij.notification.NotificationType;
import com.intellij.notification.Notifications;
import com.intellij.openapi.actionSystem.AnAction;
import com.intellij.openapi.actionSystem.AnActionEvent;
import com.intellij.openapi.wm.WindowManager;

import javax.swing.*;


public class NotificationSample extends AnAction {
    public void actionPerformed(AnActionEvent e) {

        // 表示される
        Notifications.Bus.notify(new Notification("Sample", "Title1", "content1", NotificationType.INFORMATION));

        // ダイアログの表示
        SampleDialog sampleDialog = new SampleDialog();
        sampleDialog.setLocationRelativeTo(WindowManager.getInstance().getFrame(e.getProject()).getComponents()[0]);
        sampleDialog.setVisible(true);

        // 表示されない
        Notifications.Bus.notify(new Notification("Sample", "Title2", "content2", NotificationType.INFORMATION));

        // 表示される
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                Notifications.Bus.notify(new Notification("Sample", "Title3", "content3", NotificationType.INFORMATION));
            }
        });
    }
}