Question

我想调试一个对象从这一行返回null的原因

debug_log = LoggingConfigFileLoader.getLogFilePaths().get("debug.log");

在这里：https://github.com/UniversalMediaServer/UniversalMediaServer/blob/master/src/main/java/net/pms/PMS.java#L356

我希望在发生异常之前知道发生了什么。不幸的是，.jar来自一个大项目，可能很难建立。特别是对我来说，谁也不懂java。这是在openjdk7上，（java开发人员也使用它）。但是，在FreeBSD上运行之前从未使用过该代码。

最后，我想找到这个未处理异常的真正原因/根本原因：

ums4 UMS/ root~# /usr/local/openjdk7/bin/java -Djava.awt.headless=true -classpath /usr/local/share/universal-media-server/ums.jar net.pms.PMS 18:18:12.424 [main] DEBUG o.a.c.c.ConfigurationUtils - ConfigurationUtils.locate(): base is null, name is /root/.config/UMS/UMS.conf 18:18:12.430 [main] DEBUG o.a.c.c.DefaultFileSystem - Could not locate file /root/.config/UMS/UMS.conf at null: no protocol: /root/.config/UMS/UMS.conf 18:18:12.431 [main] DEBUG o.a.c.c.ConfigurationUtils - Loading configuration from the absolute path /root/.config/UMS/UMS.conf 18:18:12.431 [main] DEBUG o.a.c.c.PropertiesConfiguration - Base path set to file:///root/.config/UMS/UMS.conf 18:18:12.463 [main] DEBUG o.a.c.c.PropertiesConfiguration - FileName set to UMS.conf 18:18:12.464 [main] DEBUG o.a.c.c.PropertiesConfiguration - Base path set to /root/.config/UMS 18:18:12.480 [main] DEBUG n.p.c.ConfigurationReader - Reading cred.path: default: "", current: "/root/.config/UMS/UMS.cred" 18:18:12.498 [main] INFO net.pms.PMS - Starting Universal Media Server 4.0.0-a1 18:18:12.499 [main] INFO net.pms.PMS - Based on PS3 Media Server by shagrath, copyright 2008-2014 18:18:12.499 [main] INFO net.pms.PMS - http://www.universalmediaserver.com 18:18:12.499 [main] INFO net.pms.PMS - 18:18:12.499 [main] INFO net.pms.PMS - Build: 38318285b (2014-06-02) 18:18:12.499 [main] INFO net.pms.PMS - Java: OpenJDK 64-Bit Server VM 1.7.0_60 64-bit by Oracle Corporation 18:18:12.500 [main] INFO net.pms.PMS - OS: FreeBSD 64-bit 9.2-RELEASE-p3 18:18:12.500 [main] INFO net.pms.PMS - Encoding: US-ASCII 18:18:12.522 [main] INFO net.pms.PMS - Memory: 313 MB 18:18:12.522 [main] INFO net.pms.PMS - Language: en 18:18:12.522 [main] INFO net.pms.PMS - 18:18:12.523 [main] INFO net.pms.PMS - Working directory: /var/db/universal-media-server/.config/UMS 18:18:12.525 [main] INFO net.pms.PMS - Temp directory: /tmp/universalmediaserver 18:18:12.525 [main] INFO net.pms.PMS - Logging config file: internal defaults 18:18:12.526 [main] INFO net.pms.PMS - 18:18:12.526 [main] INFO net.pms.PMS - Profile directory: /root/.config/UMS 18:18:12.527 [main] INFO net.pms.PMS - Profile directory permissions: rw 18:18:12.527 [main] INFO net.pms.PMS - Profile path: /root/.config/UMS/UMS.conf 18:18:12.527 [main] INFO net.pms.PMS - Profile permissions: rw 18:18:12.527 [main] INFO net.pms.PMS - Profile name: ums4 18:18:12.528 [main] INFO net.pms.PMS - 18:18:12.528 [main] INFO net.pms.PMS - Web conf path: /root/.config/UMS/WEB.conf 18:18:12.528 [main] INFO net.pms.PMS - Web conf permissions: file not found 18:18:12.528 [main] INFO net.pms.PMS - 18:18:12.540 [main] ERROR net.pms.PMS - A serious error occurred during PMS init java.lang.NullPointerException: null at net.pms.newgui.DbgPacker.<init>(DbgPacker.java:40) ~[ums.jar:4.0.0-a1] at net.pms.PMS.displayBanner(PMS.java:357) [ums.jar:4.0.0-a1] at net.pms.PMS.init(PMS.java:509) [ums.jar:4.0.0-a1] at net.pms.PMS.createInstance(PMS.java:1038) [ums.jar:4.0.0-a1] at net.pms.PMS.main(PMS.java:1138) [ums.jar:4.0.0-a1]

Answer 1

您可以尝试将项目加载到IDE中并设置＆＃34;中断异常＆＃34;断点（例如在Eclipse中它＆＃34;运行 - ＆gt;添加Java异常断点...＆＃34;）。

但我相信这种方法仅适用于相对较小的项目。例如，昨天我厌倦了等待，而番石榴的前提条件检查中断了长批处理的执行，我添加了一些日志记录并重新运行了没有调试器的过程。所以YMMV。

如何在执行停止在nullpointerexception之前调试预编译的jar文件？

1 个答案: