Question

所以我创造了一个不久前工作的简单游戏。但是，最近，当我尝试在任何浏览器中运行它时，它只给我一个NullPointerException。线程堆栈如下：

cache: Initialize resource manager: com.sun.deploy.cache.ResourceProviderImpl@18a270a
security: property package.access value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.
security: property package.access new value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp
security: property package.definition value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.
security: property package.definition new value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp
security: property package.access value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp
security: property package.access new value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp,org.mozilla.jss
security: property package.definition value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp
security: property package.definition new value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp,org.mozilla.jss
security: property package.access value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp,org.mozilla.jss
security: property package.access new value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp,org.mozilla.jss,com.sun.browser,com.sun.glass,com.sun.javafx,com.sun.media.jfxmedia,com.sun.media.jfxmediaimpl,com.sun.openpisces,com.sun.prism,com.sun.scenario,com.sun.t2k,com.sun.webpane,com.sun.pisces,com.sun.webkit
security: property package.definition value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp,org.mozilla.jss
security: property package.definition new value sun.,com.sun.xml.internal.,com.sun.imageio.,com.sun.istack.internal.,com.sun.jmx.,com.sun.proxy.,com.sun.org.apache.bcel.internal.,com.sun.org.apache.regexp.internal.,com.sun.org.apache.xerces.internal.,com.sun.org.apache.xpath.internal.,com.sun.org.apache.xalan.internal.extensions.,com.sun.org.apache.xalan.internal.lib.,com.sun.org.apache.xalan.internal.res.,com.sun.org.apache.xalan.internal.templates.,com.sun.org.apache.xalan.internal.utils.,com.sun.org.apache.xalan.internal.xslt.,com.sun.org.apache.xalan.internal.xsltc.cmdline.,com.sun.org.apache.xalan.internal.xsltc.compiler.,com.sun.org.apache.xalan.internal.xsltc.trax.,com.sun.org.apache.xalan.internal.xsltc.util.,com.sun.org.apache.xml.internal.res.,com.sun.org.apache.xml.internal.serializer.utils.,com.sun.org.apache.xml.internal.utils.,com.sun.org.apache.xml.internal.security.,com.sun.org.glassfish.,org.jcp.xml.dsig.internal.,com.sun.java.accessibility.,com.sun.javaws,com.sun.deploy,com.sun.jnlp,org.mozilla.jss,com.sun.browser,com.sun.glass,com.sun.javafx,com.sun.media.jfxmedia,com.sun.media.jfxmediaimpl,com.sun.openpisces,com.sun.prism,com.sun.scenario,com.sun.t2k,com.sun.webpane,com.sun.pisces,com.sun.webkit
basic: Added progress listener: sun.plugin.util.ProgressMonitorAdapter@13b7c28
network: Cache entry not found [url: file:////files5.ad.lake.stark.k12.oh.us/shd/2015/15TROYERJONATHAN/Documents/Computer%20Science/Game/GUI.class, version: null]
network: Cache entry not found [url: file:////files5.ad.lake.stark.k12.oh.us/shd/2015/15TROYERJONATHAN/Documents/Computer%20Science/Game/, version: null]
security: Accessing keys and certificate in Mozilla user profile: null
network: Created version ID: 1.7.0.25
network: Created version ID: 1.7.0.25
security: SSV validation: running: 1.7.0_25, requested: null, range: null
network: Created version ID: 1.7.0.25
network: Created version ID: 1.7.0.25
security: continue with running version
network: Cache entry not found [url: file:////files5.ad.lake.stark.k12.oh.us/shd/2015/15TROYERJONATHAN/Documents/Computer%20Science/Game/ColorPanel.class, version: null]
basic: Applet loaded.
basic: Applet resized and added to parent container
basic: PERF: AppletExecutionRunnable - applet.init() BEGIN ; jvmLaunch dt 216867 us, pluginInit dt 217500 us, TotalTime: 434367 us
java.lang.NullPointerException
    at GUI.init(GUI.java:70)
    at com.sun.deploy.uitoolkit.impl.awt.AWTAppletAdapter.init(Unknown Source)
    at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
basic: Removed progress listener: sun.plugin.util.ProgressMonitorAdapter@13b7c28
security: Reset deny session certificate store

这是错误的地方（至少据我所知）：

URL url=getCodeBase();
String u=url.toString();

小程序在JCreator中运行时工作正常，但在任何浏览器或Adobe Dreamweaver中都不行。我不知道任何线程堆栈意味着什么。如果有人能解释，那将非常有帮助。如果你想要代码（它很长而且很乱），请发送电子邮件至spidermaninja@gmail.com。

Answer 1

我认为GUI是applet类的名称。（顺便说一下，如果你定义了package它应该很好，但它对这个问题没有影响）

从您传输的跟踪中的堆栈跟踪，我还可以假设您在问题中输入的两行代码是第69行和第70行。

我可以假设getCodeBase()返回null，以便以下行自动转到NullPointerException（NPE）。 Starting from Java 7 update 25, getCodeBase() returns null when the applet is running from the local file system.

因此，您应该检查getCodeBase（）返回的值是否为null，这样您的代码可能如下所示：

String u = "Some default value";
URL url=getCodeBase();
if(url != null) {
    u=url.toString();
}

Java applet在IDE中工作，但在浏览器中不工作

1 个答案: