I want to put a "placeholder" in a JtextField in Java

Question

This is my code, I want to add a placeholder to the JtextField, I have watched several YouTube videos but they don't work, I have tried with libraries but it didn't work either, I have tried with JtextArea but it doesn't work either I have tried with several things but it still doesn't work. Here is my code and an image where I want to add the placeholder.

package Mantenimiento;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;

import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.table.DefaultTableModel;


public class Alumno extends JDialog implements WindowListener {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    public static String al;
    private JTextField txtadicionar;
    private JTextField txtconsulta;
    private JTextField txtmodificar;
    private JTextField txteliminar;
    private JTable tblTabla;
    private DefaultTableModel modelo;
    private JTextField textField_1;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        try {
            //@SuppressWarnings("unused")
            Alumno dialog = new Alumno();
            //dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
            dialog.setVisible(true);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Create the dialog.
     */
    public Alumno() {
        setTitle("Alumno");
        addWindowListener(this);
        setAlwaysOnTop(true);
        al="alumno";
        setBounds(100, 100, 813, 397);
        getContentPane().setLayout(null);
        
        JButton btnAdicionar = new JButton("adicionar");
        btnAdicionar.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
            }
        });
        btnAdicionar.setBounds(10, 85, 89, 23);
        getContentPane().add(btnAdicionar);
        
        JButton btnConsultar = new JButton("Consultar");
        btnConsultar.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
            }
        });
        btnConsultar.setBounds(10, 119, 89, 23);
        getContentPane().add(btnConsultar);
        
        JButton btnModificar = new JButton("modificar");
        btnModificar.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
            }
        });
        btnModificar.setBounds(10, 153, 89, 23);
        getContentPane().add(btnModificar);
        
        JButton btnEliminar = new JButton("eliminar");
        btnEliminar.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
            }
        });
        btnEliminar.setBounds(10, 187, 89, 23);
        getContentPane().add(btnEliminar);
        
        
        //esto_es_donde_dentra_los datos 
        txtadicionar = new JTextField();
        txtadicionar.setBounds(266, 40, 100, 21);
        getContentPane().add(txtadicionar);
        txtadicionar.setColumns(10);
        
        txtconsulta = new JTextField();
        txtconsulta.setBounds(399, 40, 100, 20);
        getContentPane().add(txtconsulta);
        txtconsulta.setColumns(10);
        
        txtmodificar = new JTextField();
        txtmodificar.setBounds(534, 40, 100, 20);
        getContentPane().add(txtmodificar);
        txtmodificar.setColumns(10);
        
        txteliminar = new JTextField();
        txteliminar.setBounds(665, 40, 100, 20);
        getContentPane().add(txteliminar);
        txteliminar.setColumns(10);
        
        JLabel lblCodigo = new JLabel("ingrese un codigo");
        lblCodigo.setBounds(134, 11, 119, 23);
        getContentPane().add(lblCodigo);
        
        textField_1 = new JTextField();
        textField_1.setBounds(134, 40, 86, 20);
        getContentPane().add(textField_1);
        textField_1.setColumns(10);
        
        JScrollPane scrollPane = new JScrollPane();
        scrollPane.setBounds(109, 85, 678, 262);
        getContentPane().add(scrollPane);
        
        
        //esto_es la_tabla
        tblTabla = new JTable();
        tblTabla.setBorder(null);
        tblTabla.setFillsViewportHeight(true);
        scrollPane.setViewportView(tblTabla);
        
        modelo = new DefaultTableModel();
        modelo.addColumn("codigo");
        modelo.addColumn("nombre");
        modelo.addColumn("nota 1");
        modelo.addColumn("nota2");
        modelo.addColumn("promedio");
        tblTabla.setModel(modelo);
        
    }
}