Título: Duda con un fragmento de codigo en java
Publicado por: NightSeiger en 2 Enero 2016, 04:57 am
Este es un método de un ejemplo que venia en un libro y mi duda es el porqué de las llaves que aparecen dentro de ella debajo de estas 3 sentencias : JPanel leftPane = new JPanel(); JPanel centerPane = new JPanel(); JPanel toolbar = new JPanel(); como se llama ese tipo de uso de llaves, ¿que finalidad tiene?, ¿en que casos se usan? Gracias de antemano. private void makeFrame(String[] audioFiles) { // the following makes sure that our application exits when // the user closes its window setDefaultCloseOperation(EXIT_ON_CLOSE); JPanel contentPane = (JPanel)getContentPane(); contentPane.setBorder(new EmptyBorder(6, 10, 10, 10));
makeMenuBar(); // Specify the layout manager with nice spacing contentPane.setLayout(new BorderLayout(8, 8));
// Create the left side with combobox and scroll list JPanel leftPane = new JPanel(); { leftPane.setLayout(new BorderLayout(8, 8));
String[] formats = { "all formats", ".wav", ".au", ".aif" }; // Create the combo box. JComboBox formatList = new JComboBox(formats); formatList.addActionListener(this); leftPane.add(formatList, BorderLayout.NORTH); // Create the scrolled list for file names fileList = new JList(audioFiles); fileList.setForeground(new Color(140,171,226)); fileList.setBackground(new Color(0,0,0)); fileList.setSelectionBackground(new Color(87,49,134)); fileList.setSelectionForeground(new Color(140,171,226)); JScrollPane scrollPane = new JScrollPane(fileList); scrollPane.setColumnHeaderView(new JLabel("Audio files")); leftPane.add(scrollPane, BorderLayout.CENTER); } contentPane.add(leftPane, BorderLayout.CENTER);
// Create the center with image, text label, and slider JPanel centerPane = new JPanel(); { centerPane.setLayout(new BorderLayout(8, 8)); JLabel image = new JLabel(new ImageIcon("title.jpg")); centerPane.add(image, BorderLayout.NORTH); centerPane.setBackground(Color.BLACK);
infoLabel = new JLabel(" "); infoLabel.setHorizontalAlignment(SwingConstants.CENTER); infoLabel.setForeground(new Color(140,171,226)); centerPane.add(infoLabel, BorderLayout.CENTER);
slider = new JSlider(0, 100, 0); TitledBorder border = new TitledBorder("Seek"); border.setTitleColor(Color.white); slider.setBorder(new CompoundBorder(new EmptyBorder(6, 10, 10, 10), border)); slider.addChangeListener(this); slider.setBackground(Color.BLACK); slider.setMajorTickSpacing(25); slider.setPaintTicks(true); centerPane.add(slider, BorderLayout.SOUTH); } contentPane.add(centerPane, BorderLayout.EAST);
// Create the toolbar with the buttons JPanel toolbar = new JPanel(); { toolbar.setLayout(new GridLayout(1, 0)); JButton button = new JButton("Play"); button.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { play(); } }); toolbar.add(button); button = new JButton("Stop"); button.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { stop(); } }); toolbar.add(button); button = new JButton("Pause"); button.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { pause(); } }); toolbar.add(button); button = new JButton("Resume"); button.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { resume(); } }); toolbar.add(button); } contentPane.add(toolbar, BorderLayout.NORTH);
// building is done - arrange the components pack(); // place this frame at the center of the screen and show Dimension d = Toolkit.getDefaultToolkit().getScreenSize(); setLocation(d.width/2 - getWidth()/2, d.height/2 - getHeight()/2); setVisible(true); }
Título: Re: Duda con un fragmento de codigo en java
Publicado por: jhonatanAsm en 2 Enero 2016, 07:28 am
se utiliza para definir un scope: http://www.java2s.com/Tutorial/Java/0020__Language/VariableScopeinablock.htm
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