Try to add a scrollpane to a JTable component

I try to make a scrollbar on my JTable, but it not works. I have a JTable with 21 rows and 5 columns. I have a scrollpane object, and I constructs this like

public Targy_felv() {
 
     JScrollPane scrollPane;
     JFrame frame = new JFrame();
     frame.setVisible(true);
     frame.setSize(600, 300);
     table = new JTable();
     Object o[] = new Object[]{"Tárgynév", "Oktató", "Kredit", "Félév", "Tárgykód"};
     table.setModel(new DefaultTableModel(get_Tárgyak(), o));
     scrollPane = new JScrollPane();
     scrollPane.getViewport().add(table);
     frame.add(table);
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 }
 

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