Добавление элементов во вкладки JTabbedPane - Java

import java.awt.*;
import javax.swing.*;
 
public class Builder{
 
    public static void main(String[] args) {
        createInterface();      
    }
    
    public static void createInterface(){
        Windows windows = new Windows();
        windows.createTabbedPane("MainTab");
        windows.createTab(windows.getJTabbedPane("MainTab"), "Search");
        windows.createTab(windows.getJTabbedPane("MainTab"), "History");
        windows.createPanel("SearchPanel", (Container)windows.getJTabbedPane("MainTab").getTabComponentAt(0));
    }
 
}

import java.awt.*;
import java.util.*;
import javax.swing.*;
 
public class Windows extends JFrame {
    public Windows(){
        createMainWindow();
        jTabbedPanes = new HashMap<String, JTabbedPane>();
        jPanels = new HashMap<String, JPanel>();
    }
    public void createTabbedPane(String tpName){
        JTabbedPane tPane = new JTabbedPane();
        this.add(tPane);
        jTabbedPanes.put(tpName, tPane);
    }
    public void createTab(JTabbedPane tPane, String tName){
        tPane.addTab(tName, new JPanel());
    }
    public void createPanel(String pName, Container c){
        JPanel jPanel = new JPanel();
        jPanel.setName(pName);
        c.add(jPanel);
        jPanels.put(pName, jPanel);
    }
    public void createButton(){}
    public void createLabel(){}
    public JTabbedPane getJTabbedPane(String tpName){
        return jTabbedPanes.get(tpName);
    }
    private void createMainWindow(){
        setSize(400, 300);
        setTitle("Searcher");
        setLocationRelativeTo(null); //узнать что это
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setVisible(true);
    }
    private HashMap<String, JTabbedPane> jTabbedPanes;
    private HashMap<String, JPanel> jPanels;
}