JAVA 中 -> 是什么意思？

import javax.swing.*;import java.awt.*;import java.io.File; public class ImageViewer {    public static void main(String[] args){        EventQueue.invokeLater(() -> {            JFrame frame = new ImageViewerFrame();            frame.setTitle("ImageViewer");            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);            frame.setVisible(true);         });    }}class ImageViewerFrame extends JFrame{    private JLabel label;    private JFileChooser chooser;    private static final int DEFAULT_WIDTH = 300;    private static final int DEFAULT_HEIGHT = 400;     public ImageViewerFrame(){        setSize(DEFAULT_WIDTH,DEFAULT_HEIGHT);         label = new JLabel();        add(label);         chooser = new JFileChooser();        chooser.setCurrentDirectory(new File("."));         JMenuBar menuBar = new JMenuBar();        setJMenuBar(menuBar);        JMenu menu = new JMenu();        menuBar.add(menu);         JMenuItem openItem = new JMenuItem("open");        menu.add(openItem);        openItem.addActionListener(Event -> {            int result = chooser.showOpenDialog(null);             if (result == JFileChooser.APPROVE_OPTION){                String name = chooser.getSelectedFile().getPath();                label.setIcon(new ImageIcon(name));            }        });         JMenuItem exitItem = new JMenuItem("exit");        menu.add(exitItem);        exitItem.addActionListener(Event -> System.exit(0));    }}

() -> {            JFrame frame = new ImageViewerFrame();            frame.setTitle("ImageViewer");            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);            frame.setVisible(true);         }

Event -> {            int result = chooser.showOpenDialog(null);             if (result == JFileChooser.APPROVE_OPTION){                String name = chooser.getSelectedFile().getPath();                label.setIcon(new ImageIcon(name));            }

EventQueue.invokeLater(new Runnable() {            public void run() {                JFrame frame = new ImageViewerFrame();                frame.setTitle("ImageViewer");                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);                frame.setVisible(true);            }        });

openItem.addActionListener(new ActionListener() {            public void actionPerformed(ActionEvent e) {                int result = chooser.showOpenDialog(null);                 if (result == JFileChooser.APPROVE_OPTION){                    String name = chooser.getSelectedFile().getPath();                    label.setIcon(new ImageIcon(name));                }            }        });