小编tvo*_*olf的帖子

起初,抱歉我的英语不好.我有代码片段:

long x = 9223372036854775807L;
double f = x;
Console.WriteLine(x);           
Console.WriteLine(f);

输出是:

9223372036854775807
9,22337203685478E+18

编译和执行此代码时,我没有收到任何错误.在将Long转换为Double时,我们的精度会下降.为什么C#在这种情况下不需要显式转换？

谢谢大家.

我已经创建了简单的代码片段来演示JAVA的一些奇怪的东西.

public class Start extends JFrame {

    public static JFrame mainFrame; 

    public static void main(String[] args) {

        JFrame f = new JFrame();
        mainFrame = f;
        f.setSize(400, 400);

        Action btn_action = new AbstractAction() {
            public void actionPerformed(ActionEvent arg0) {
                System.out.println("test");
                JDialog d = new JDialog(mainFrame, "Test Dialog", true);
                d.setSize(200, 200);
                d.setLocationRelativeTo(null);
                JTextField text = new JTextField();
                d.add(text);
                d.setVisible(true);
            }
        };

        JButton btn = new JButton(btn_action);
        btn.setText("Click me");
        KeyStroke btnShortcut = KeyStroke.getKeyStroke(KeyEvent.VK_1, 0);
        btn.getActionMap().put("btn_click", btn_action);
        btn.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(btnShortcut, "btn_click");
        f.add(btn);
        f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    } …