java - 图标图像 "error java.lang.NullPointerException"

Question

嗯，我正在尝试设置我的图标图像，但我不断收到此错误......

代码:

public static void browser(){
        Image myicon = null;
        myicon.equals("images/icon.gif");
        try {
            UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
        } catch (ClassNotFoundException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (InstantiationException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (IllegalAccessException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (UnsupportedLookAndFeelException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }
        JFrame frame = new JFrame("Kloke - Become invisable.");
        frame.setSize(350, 100);
        frame.setResizable(false);
        frame.setIconImage(myicon);

错误:

Exception in thread "main" java.lang.NullPointerException
        at web.browser(web.java:14)
        at Checkupdate.main(Checkupdate.java:102)

PS。我是 java 新手，所以请随意对待我，就好像我不知道我在做什么一样(PSS 第 14 行是我初始化“myicon”变量的地方。)

Answer 1

尝试在尚未实例化的对象上调用任何实例方法都将导致NullPointerException。您需要实例化 myicon

Image myicon = ImageIO.read(new File("images/icon.gif"));