java - jlable 的问题

Question

String str1 ="C:\Users\mehdi\Documents\NetBeansProjects\project1\src\res\1 (21).png ";
String str2 =" \res\1 (21).png";
jLabel24.setIcon(new ImageIcon(getClass().getResource( ? ) ) );

字符串str1、str2的路径相同。

但是当我使用 str1 而不是 ? 时，会引发异常。但是当我放入str2时，它没有任何问题。

有什么问题吗？怎么解决呢？

我将 str1 更改为

str1 = “C:\\Users\mehdi\\Documents\\NetBeansProjects\\project1\\src\\res\\1 (21).png”

和

jLabel24.setIcon(new ImageIcon(?) );

但是抛出了这个异常。

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at javax.swing.ImageIcon.<init>(ImageIcon.java:167)
    at project1.NewUser.jButton7ActionPerformed(NewUser.java:1173)
    at project1.NewUser.access$1100(NewUser.java:30)
    at project1.NewUser$12.actionPerformed(NewUser.java:326)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
    at java.awt.Component.processMouseEvent(Component.java:6267)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
    at java.awt.Component.processEvent(Component.java:6032)
    at java.awt.Container.processEvent(Container.java:2041)
    at java.awt.Component.dispatchEventImpl(Component.java:4630)
    at java.awt.Container.dispatchEventImpl(Container.java:2099)
    at java.awt.Component.dispatchEvent(Component.java:4460)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4577)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4238)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168)
    at java.awt.Container.dispatchEventImpl(Container.java:2085)
    at java.awt.Window.dispatchEventImpl(Window.java:2478)
    at java.awt.Component.dispatchEvent(Component.java:4460)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

Answer 1

这里有很多问题:

• 字符串文字中有未转义的反斜杠
• 您在调用 getResource 时使用了反斜杠，我相信它是为与正斜杠一起使用而设计的
• 您假设 Class.getResource 采用文件名。它没有 - 它需要一个资源名称。您无法使用 Class.getResource() 访问文件系统上任何位置的任意文件；这不是它的用途。

如果您想从文件名创建 ImageIcon，只需使用 ImageIcon(String) 构造函数:

String str1 = "c:\\Users\\mehdi\\...";
jLabel24.setIcon(new ImageIcon(str1));