Swing Komponenten erst nach Resize sichtbar

[Lucaaa]

Hey!
Warum werden meine Komponenten speziell das JSplitPane erst nach dem Resize des Fensters sichtbar?

package com.ludevstudio.passwordmanager;
import java.awt.BorderLayout;
import javax.swing.JFrame;
public class MainFrame extends JFrame{
 /* This Class contains the Main Frame
   This is only the blank window. */
 
 MainPane mainPane;
 
 
 
 // Set params for the Window
 public MainFrame() {
  setTitle("Password Manager v1.0");
  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  setLayout(new BorderLayout() );
  setVisible(true);
  
  
  // only in Dev Phase:
  setSize(800, 800);
  setLocationRelativeTo(null);
  
  
  initComponents(); // Call initComponents
 }
 
 // init and add the Panels
 public void initComponents() {
  mainPane = new MainPane();
  add(mainPane, BorderLayout.CENTER);
 }
}

package com.ludevstudio.passwordmanager;
import java.awt.BorderLayout;
import java.awt.Dimension;
import javax.swing.JSplitPane;
public class MainPane extends JSplitPane {
 // This Class contains the main Interface.
 
 // Set params for the Pane
 public MainPane() {
  
  setLeftComponent(new ManagerPanel());
  setRightComponent(new ActionsPanel());
  setDividerLocation(500);
  
 }
 
}

package com.ludevstudio.passwordmanager;
import java.awt.Dimension;
import javax.swing.JPanel;
public class ManagerPanel extends JPanel{
 // This Class contains the Manager
 
 // Constructor and params
 public ManagerPanel() {
  
  setMinimumSize(new Dimension(400, 100));
 }
 
 
}

package com.ludevstudio.passwordmanager;
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.JPanel;

public class ActionsPanel  extends JPanel{ 
 // THis Class contains the Action Buttons on the right side.
 
 
 // Constructor and params
 public ActionsPanel()  {
  setBackground(Color.BLUE);
  setMinimumSize(new Dimension(150, 150));
  setMaximumSize(new Dimension(200, 1000));
 }
}

Ich Hoffe ihr könnt mir Helfen.
Danke schonmal!

 

[Robat]

setVisible(true) erst am Ende aufrufen, wenn alle Komponenten hinzugefügt wurden.

 

[Lucaaa]

Danke!