Non credo di aver capito bene ti do tutto il codice e chiedo se per favore potresti farmi un esempio con il primo (mi riferisco a jTextField2.setText(Integer.toBinaryString(...)) :

package convertitore;

public class NewJFrame extends javax.swing.JFrame {

public NewJFrame() {
initComponents();
}

@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {

jLabel1 = new javax.swing.JLabel();
jTextField1 = new javax.swing.JTextField();
jButton1 = new javax.swing.JButton();
jLabel2 = new javax.swing.JLabel();
jButton2 = new javax.swing.JButton();
jButton3 = new javax.swing.JButton();
jTextField2 = new javax.swing.JTextField();
jLabel3 = new javax.swing.JLabel();

setDefaultCloseOperation(javax.swing.WindowConstan ts.EXIT_ON_CLOSE);

jLabel1.setText("Scrivi il numero che vuoi convertire:");

jTextField1.setText("");

jButton1.setText("Binario");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});

jLabel2.setText("Converti in:");

jButton2.setText("Esadecimale");
jButton2.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton2ActionPerformed(evt);
}
});

jButton3.setText("Ottale");
jButton3.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton3ActionPerformed(evt);
}
});

jLabel3.setText("Numero convertito:");

javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout .Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.LEADING)
.addComponent(jLabel2)
.addGroup(layout.createSequentialGroup()
.addComponent(jButton1)
.addPreferredGap(javax.swing.LayoutStyle.Component Placement.UNRELATED)
.addComponent(jButton2)
.addGap(10, 10, 10)
.addComponent(jButton3))
.addComponent(jLabel3)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.TRAILING, false)
.addComponent(jTextField2, javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jTextField1, javax.swing.GroupLayout.Alignment.LEADING)
.addComponent(jLabel1, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))
.addContainerGap(161, Short.MAX_VALUE))
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout .Alignment.LEADING)
.addGroup(layout.createSequentialGroup()
.addContainerGap()
.addComponent(jLabel1)
.addPreferredGap(javax.swing.LayoutStyle.Component Placement.RELATED)
.addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addPreferredGap(javax.swing.LayoutStyle.Component Placement.RELATED)
.addComponent(jLabel2)
.addPreferredGap(javax.swing.LayoutStyle.Component Placement.UNRELATED)
.addGroup(layout.createParallelGroup(javax.swing.G roupLayout.Alignment.BASELINE)
.addComponent(jButton1)
.addComponent(jButton2)
.addComponent(jButton3))
.addPreferredGap(javax.swing.LayoutStyle.Component Placement.UNRELATED)
.addComponent(jLabel3)
.addPreferredGap(javax.swing.LayoutStyle.Component Placement.UNRELATED)
.addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
.addContainerGap(139, Short.MAX_VALUE))
);

pack();
}// </editor-fold>

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
jTextField2.setText(Integer.toBinaryString(...));
}

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {

}

private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {

}


public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new NewJFrame().setVisible(true);
}
});
}

// Variables declaration - do not modify
private javax.swing.JButton jButton1;
private javax.swing.JButton jButton2;
private javax.swing.JButton jButton3;
private javax.swing.JLabel jLabel1;
private javax.swing.JLabel jLabel2;
private javax.swing.JLabel jLabel3;
private javax.swing.JTextField jTextField1;
private javax.swing.JTextField jTextField2;
// End of variables declaration

}