Konversi Bilangan

  public static int pangkat (int a, int b){
    int hasil=1;
    for(int i=1;i<=b;i++){
        hasil=hasil*a;
    }
    return hasil;
}
    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                        
        // TODO add your handling code here:
      
        String bin = "";
        String bilbiner = "";
        int nilaiawal = 0;
        int nilaisisa;
        int hasilbagi = 0;
        String hasil;

        nilaiawal = Integer.parseInt(txtnilai.getText());
        if (jComboBox1.getSelectedIndex()== 0){
            hasilbagi = nilaiawal/2;
            while(hasilbagi>=1){
                nilaisisa = nilaiawal % 2;
                if (nilaisisa == 0){
                    bin="0";
                }else if (nilaisisa == 1){
                    bin ="1";
                }bilbiner = bin + bilbiner;
                nilaiawal = hasilbagi;
                hasilbagi = nilaiawal/2;
            }
            if (nilaiawal>0){
                hasil = "1"+bilbiner;
            }else {
                hasil = "0";
            }
            txthasil.setText(String.valueOf(hasil));
        }else if (jComboBox1.getSelectedIndex()==1){
            String biner = txtnilai.getText();
            int n, sum;
            int hasilbiner;
            char b[]= new char [1000];
            n=biner.length();
            sum=0;
            for (int i=1;i<=n;i++){
                b[i]=biner.charAt(i-1);
            }
            for (int i=n-1;i>=0;i--){
                if(b[n-i]=='0'){
                sum=sum+0*pangkat(2,i);
                }else if(b[n-i]=='1'){
                sum=sum+1*pangkat(2,i);
                }
            }
            hasilbiner=sum;
            txthasil.setText(String.valueOf(hasilbiner));
        }
    }                                       

    private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                        
        // TODO add your handling code here:
        txtnilai.setText("");
        txthasil.setText("");
    }                                       

    private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {                                        
        // TODO add your handling code here:
        System.exit(0);
    }