CaesarChipper GUI

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public final class Chipper extends JFrame{

    final String KEY_ERROR="Invalid Key";
    final String IS_STRING="1 karakter untuk key";
    final String TEXTFIELD_EMPTY="Text kosong";
    final String KEYFIELD_EMPTY="Key kosong";

    String hasil;
    boolean focus=false;
    JTextField res;
    JPanel panel=new JPanel();
    JLabel inTxt =new JLabel("Text  : ");
    JLabel inkey =new JLabel("Key   : ");
    JLabel resLb =new JLabel("Result: ");
    JLabel stats =new JLabel();
    JTextField txt=new JTextField(20);
    JTextField key=new JTextField(1);
    JTextField result=new JTextField(1);
    JButton enc =new JButton("Enskripsi");
    JButton dec =new JButton("Deskripsi");

    public static void main(String[]args){
        try{
            SwingUtilities.invokeLater(new Runnable() {
                @Override
                public void run() {
                    Chipper frm=new Chipper();
                }
            });
        }catch(Exception e){
            System.out.println("Gagal karena "+e);
        }
    }
    Chipper(){
        super("Chipper");
        setupFrame();
    }
    void setupFrame(){
        // Set Things Up
        panel.setBackground(Color.DARK_GRAY);
        panel.setLayout(null);
        panel.setBounds(10, 10, 200, 300);
        this.setLocationByPlatform(true);
        inTxt.setForeground(Color.WHITE);
        inkey.setForeground(Color.WHITE);
        resLb.setForeground(Color.WHITE);
        txt.setText("Text untuk enskipsi/deskripsi");
        inTxt.setBounds(20, 20, 50, 20);
        txt.setBounds(60, 20, 300, 20);
        inkey.setBounds(370, 20, 50, 20);
        key.setBounds(410, 20, 20, 20);
        enc.setBounds(60, 45, 100, 30);
        dec.setBounds(180, 45, 100, 30);
        resLb.setBounds(20, 80, 50, 20);
        result.setBounds(60, 80, 300, 20);
        stats.setBounds(300, 45, 140, 30);
        stats.setForeground(Color.red);
        txt.setForeground(Color.gray);
        // Action :V
        txt.addFocusListener(new FocusListener() {
            @Override
            public void focusGained(FocusEvent e) {
                if(!focus){
                    txt.setForeground(Color.BLACK);
                    txt.setText("");
                    focus=true;
                }
            }
            @Override
            public void focusLost(FocusEvent e) {}
        });
        enc.addMouseListener(new MouseListener() {
            @Override
            public void mouseClicked(MouseEvent e) {
                stats.setText("");
                String Skey=key.getText();
                if(txt.getText().equals("")||focus==false){
                    stats.setText(TEXTFIELD_EMPTY);
                    return;
                }
                if(Skey.length()==1){
                    Character keyC=((int)Skey.charAt(0)>96)?(char)((int)Skey.charAt(0)-32):Skey.charAt(0);
                    if(keyC>='A'&&keyC<='Z'){
                        hasil=Chipper.enskrip(txt.getText(), keyC);
                        result.setText(hasil);
                    }else{
                        stats.setText(KEY_ERROR);
                        key.setText("");
                    }
                }else if(Skey.length()<1){
                        stats.setText(KEYFIELD_EMPTY);
                }else{
                        stats.setText(IS_STRING);
                        key.setText("");
                }
            }
            @Override
            public void mousePressed(MouseEvent e) {}
            @Override
            public void mouseReleased(MouseEvent e) {}
            @Override
            public void mouseEntered(MouseEvent e) {}
            @Override
            public void mouseExited(MouseEvent e) {}
        });
        dec.addMouseListener(new MouseListener() {
            @Override
            public void mouseClicked(MouseEvent e) {
                stats.setText("");
                String Skey=key.getText();
                if(txt.getText().equals("")||focus==false){
                    stats.setText(TEXTFIELD_EMPTY);
                    return;
                }
                if(Skey.length()==1){
                    Character keyC=((int)Skey.charAt(0)>96)?(char)((int)Skey.charAt(0)-32):Skey.charAt(0);
                    if(keyC>='A'&&keyC<='Z'){
                        hasil=Chipper.deskrip(txt.getText(), keyC);
                        result.setText(hasil);
                    }else{
                        stats.setText(KEY_ERROR);
                        key.setText("");
                    }
                }else if(Skey.length()<1){
                    stats.setText(KEYFIELD_EMPTY);
                }else{
                    stats.setText(IS_STRING);
                    key.setText("");
                }
            }
            @Override
            public void mousePressed(MouseEvent e) {}
            @Override
            public void mouseReleased(MouseEvent e) {}
            @Override
            public void mouseEntered(MouseEvent e) {}
            @Override
            public void mouseExited(MouseEvent e) {}
        });
        // Put Everything here
        panel.add(inTxt);
        panel.add(txt);
        panel.add(inkey);
        panel.add(key);
        panel.add(enc);
        panel.add(dec);
        panel.add(resLb);
        panel.add(result);
        panel.add(stats);
        //Frame config
        this.add(panel);
        this.setFocusable(false);
        this.setResizable(false);
        this.setSize(new Dimension(460, 150));
        this.setVisible(true);
        this.setFocusable(true);
        this.setDefaultCloseOperation(EXIT_ON_CLOSE);
        this.setLocationByPlatform(true);
    }

    private static String enskrip(String text, char key){
        String hasil;

        return hasil;
    }

    private static String deskrip(String text, char key){
       String hasil;

       return hasil;
    }
}