Entendi, tem alguns problemas aí:
Vc setou sua janela como JPanel, mas o correto é JFrame
public class Itens extends JPanel {}
Vc adicionou Itens() no contentPane, fazendo que o seu programa nunca iniciasse, iria ficar sempre adicionando, o que causaria erro.
frame.setContentPane(new Itens());
Outro problema é q vc declarou um JFrame, isso nao é necessario:
static JFrame frame = new JFrame();
No final ficou:
//import com.kingaspx.DownloadVideo.menu.Menu;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
public class Itens extends JFrame {
private static final long serialVersionUID = 1L;
public Itens() {
initComponents();
}
private void initComponents() {
jLabel1 = new JLabel();
jLabel9 = new JLabel();
jLabel10 = new JLabel();
jLabel11 = new JLabel();
jLabel12 = new JLabel();
jLabel13 = new JLabel();
jLabel14 = new JLabel();
jButton1 = new JButton();
jLabel15 = new JLabel();
jLabel8 = new JLabel();
jLabel16 = new JLabel();
jLabel18 = new JLabel();
jLabel17 = new JLabel();
jLabel4 = new JLabel();
jLabel3 = new JLabel();
jLabel6 = new JLabel();
jLabel7 = new JLabel();
jLabel5 = new JLabel();
jLabel2 = new JLabel();
jLabel1.setFont(new java.awt.Font("Arial", 0, 36));
jLabel1.setText("Itens");
add(jLabel1);
jLabel1.setBounds(620, 0, 100, 43);
jLabel9.setFont(new java.awt.Font("Arial", 1, 36));
jLabel9.setText("Probabilidade de Drop");
add(jLabel9);
jLabel9.setBounds(470, 340, 390, 43);
jLabel10.setFont(new java.awt.Font("Arial", 0, 36));
jLabel10.setForeground(new java.awt.Color(0, 102, 0));
jLabel10.setText("Item Incomum: 50%");
add(jLabel10);
jLabel10.setBounds(500, 440, 320, 43);
jLabel11.setFont(new java.awt.Font("Arial", 0, 36));
jLabel11.setForeground(new java.awt.Color(153, 153, 153));
jLabel11.setText("Item Comum: 70%");
add(jLabel11);
jLabel11.setBounds(500, 390, 299, 43);
jLabel12.setFont(new java.awt.Font("Arial", 0, 36));
jLabel12.setForeground(new java.awt.Color(51, 153, 255));
jLabel12.setText("Item Raro: 30%");
add(jLabel12);
jLabel12.setBounds(520, 480, 250, 43);
jLabel13.setFont(new java.awt.Font("Arial", 0, 36));
jLabel13.setForeground(new java.awt.Color(255, 204, 51));
jLabel13.setText("Item Lendário 5%");
add(jLabel13);
jLabel13.setBounds(510, 580, 290, 43);
jLabel14.setFont(new java.awt.Font("Arial", 0, 36));
jLabel14.setForeground(new java.awt.Color(102, 0, 153));
jLabel14.setText("Item Épico: 15%");
add(jLabel14);
jLabel14.setBounds(520, 530, 270, 43);
jButton1.setFont(new java.awt.Font("Arial", 0, 24));
jButton1.setText("MENU");
jButton1.setContentAreaFilled(false);
jButton1.setFocusable(false);
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
add(jButton1);
jButton1.setBounds(0, 0, 187, 56);
jLabel15.setFont(new java.awt.Font("Arial", 0, 36));
jLabel15.setForeground(new java.awt.Color(102, 0, 153));
jLabel15.setText("(Roxo)");
add(jLabel15);
jLabel15.setBounds(670, 240, 110, 43);
jLabel8.setFont(new java.awt.Font("Arial", 0, 36));
jLabel8.setForeground(new java.awt.Color(255, 204, 51));
jLabel8.setText("(Dourado)");
add(jLabel8);
jLabel8.setBounds(670, 290, 170, 43);
jLabel16.setFont(new java.awt.Font("Arial", 0, 36));
jLabel16.setText("Lendário &6");
add(jLabel16);
jLabel16.setBounds(470, 290, 200, 43);
jLabel18.setFont(new java.awt.Font("Arial", 0, 36));
jLabel18.setText("Épico = &5");
add(jLabel18);
jLabel18.setBounds(490, 240, 180, 43);
jLabel17.setFont(new java.awt.Font("Arial", 0, 36));
jLabel17.setForeground(new java.awt.Color(51, 153, 255));
jLabel17.setText("(Azul Marinho)");
add(jLabel17);
jLabel17.setBounds(670, 190, 235, 43);
jLabel4.setFont(new java.awt.Font("Arial", 0, 36));
jLabel4.setText("Raro = &3");
add(jLabel4);
jLabel4.setBounds(500, 190, 163, 43);
jLabel3.setFont(new java.awt.Font("Arial", 0, 36));
jLabel3.setForeground(new java.awt.Color(0, 102, 0));
jLabel3.setText("(Verde Escuro) ");
add(jLabel3);
jLabel3.setBounds(650, 140, 260, 43);
jLabel6.setFont(new java.awt.Font("Arial", 0, 36));
jLabel6.setText("Incomum = &2");
add(jLabel6);
jLabel6.setBounds(410, 140, 240, 43);
jLabel7.setFont(new java.awt.Font("Arial", 0, 36));
jLabel7.setText("Comum = &7 ");
add(jLabel7);
jLabel7.setBounds(470, 90, 222, 43);
jLabel5.setFont(new java.awt.Font("Arial", 0, 36));
jLabel5.setForeground(new java.awt.Color(153, 153, 153));
jLabel5.setText("(Cinza)");
add(jLabel5);
jLabel5.setBounds(690, 90, 120, 43);
jLabel2.setFont(new java.awt.Font("Arial", 1, 36));
jLabel2.setText("Cor e Nome dos Itens");
add(jLabel2);
jLabel2.setBounds(470, 40, 370, 43);
setLayout(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setExtendedState(6);
setTitle("TESTE ECLIPSE");
}
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
new Menu().setVisible(true);
dispose();
}
public static void main(String[] args) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new Menu().setVisible(true);
}
});
}
private JButton jButton1;
private JLabel jLabel1;
private JLabel jLabel10;
private JLabel jLabel11;
private JLabel jLabel12;
private JLabel jLabel13;
private JLabel jLabel14;
private JLabel jLabel15;
private JLabel jLabel16;
private JLabel jLabel17;
private JLabel jLabel18;
private JLabel jLabel2;
private JLabel jLabel3;
private JLabel jLabel4;
private JLabel jLabel5;
private JLabel jLabel6;
private JLabel jLabel7;
private JLabel jLabel8;
private JLabel jLabel9;
}