maven-compiler-plugin:3.1:compile 失败。空指针异常答案

【问题标题】：maven-compiler-plugin:3.1:compile failed. NullPointerExceptionmaven-compiler-plugin:3.1:compile 失败。空指针异常
【发布时间】：2017-02-01 13:16:15
【问题描述】：

我使用 maven-compiler-plugin:3.1 得到 NullPointerException。我在 SOF 上调查过类似的问题，但没有成功。

我运行的命令：mvn compile

maven 环境：

Apache Maven 3.0.3 (rNON-CANONICAL_2011-12-28_13-22_mein; 2011-12-28 13:22:36-0600)
Maven home: /soft/maven/3.0.3
Java version: 1.6.0_38, vendor: Sun Microsystems Inc.
Java home: /soft/jdk1.6.0_38-arch/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "linux", version: "3.13.0-83-generic", arch: "amd64", family: "unix"

（它使用的是 1.6，因为这是项目需要的，一个遗留项目）

错误信息：

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project wikibrain-utils: Execution default-compile of goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile failed. NullPointerException -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project wikibrain-utils: Execution default-compile of goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile failed.
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:225)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:319)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)
Caused by: org.apache.maven.plugin.PluginExecutionException: Execution default-compile of goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile failed.
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:110)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
    ... 19 more
Caused by: java.lang.NullPointerException
    at org.apache.maven.plugin.compiler.AbstractCompilerMojo.hasNewFile(AbstractCompilerMojo.java:1198)
    at org.apache.maven.plugin.compiler.AbstractCompilerMojo.isDependencyChanged(AbstractCompilerMojo.java:1166)
    at org.apache.maven.plugin.compiler.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:648)
    at org.apache.maven.plugin.compiler.CompilerMojo.execute(CompilerMojo.java:129)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
    ... 20 more
[ERROR]
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginExecutionException
[ERROR]
[ERROR] After correcting the problems, you can resume the build with the command
[ERROR]   mvn <goals> -rf :wikibrain-utils

【问题讨论】：

3.1 已经很老了。使用最新的 3.5.1，并尝试发布一个minimal reproducible example 的问题。
不要使用 Maven 3.0.3，这确实是错误的。使用更新的版本，如 3.3.9 ...

标签： java maven maven-compiler-plugin

【解决方案1】：

在 Windows 上编译到 SMB 共享（在 NAS 上）时遇到同样的问题。

从 3.7.0 更新到 3.8.0 修复了它。

        <artifactId>maven-compiler-plugin</artifactId>
        <groupId>org.apache.maven.plugins</groupId>
        <version>3.8.0</version>

这是我得到的堆栈跟踪的一部分，以防它帮助其他人找到相同的问题。

原因：java.lang.NullPointerException 在 org.apache.maven.plugin.compiler.AbstractCompilerMojo.hasNewFile (AbstractCompilerMojo.java:1574)

【讨论】：

【解决方案2】：

我已经解决了这个问题 - 它恰好是文件权限问题。

艾伦

【讨论】：

哪个文件需要权限？/