Stream map如何导致index out of bounds错误

Question

上下文：我正在开发 Maven 插件。

我正在使用 MavenProject 的依赖项列表，因此我想转换为字符串数组。

import org.apache.maven.project.MavenProject;

@Parameter(...)
private MavenProject project;

// Getting Dependencies
List<Dependency> depsList = project.getDependencies();

以下解决方案效果很好：

ArrayList<String> depsArrayList = new ArrayList<String>();
for ( Dependency d : depsList){
    getLog().info(d.getArtifactId()); //OK, displays each dependency
    depsArrayList.add(d.getArtifactId());
}

我想改用地图。

List<String> depsStringList = depsList.stream()
            .map(d -> d.getArtifactId())
            .collect(Collectors.toList());

但我收到以下错误：

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-plugin-plugin:3.2:descriptor (default-descriptor) on project mjext-maker-maven-plugin: Execution default-descriptor of goal org.apache.maven.plugins:maven-plugin-plugin:3.2:descriptor failed: Index 52264 out of bounds for length 154 -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-plugin-plugin:3.2:descriptor (default-descriptor) on project mjext-maker-maven-plugin: Execution default-descriptor of goal org.apache.maven.plugins:maven-plugin-plugin:3.2:descriptor failed: Index 52264 out of bounds for length 154
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:215)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:972)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:293)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:196)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
Caused by: org.apache.maven.plugin.PluginExecutionException: Execution default-descriptor of goal org.apache.maven.plugins:maven-plugin-plugin:3.2:descriptor failed: Index 52264 out of bounds for length 154
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:148)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:972)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:293)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:196)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:566)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
Caused by: java.lang.ArrayIndexOutOfBoundsException: Index 52264 out of bounds for length 154
    at org.objectweb.asm.ClassReader.readClass (Unknown Source)
    at org.objectweb.asm.ClassReader.accept (Unknown Source)
    at org.objectweb.asm.ClassReader.accept (Unknown Source)
    at org.apache.maven.tools.plugin.annotations.scanner.DefaultMojoAnnotationsScanner.scanDirectory (DefaultMojoAnnotationsScanner.java:205)

我知道什么是 ArrayOutOfBound 错误，但我不知道这个错误是从哪里来的。

如果我分成更多的步骤:

Stream<Dependency> depsStream = depsList.stream();
Stream<String> stringDepsStream = depsStream.map(Dependency::getArtifactId);
List<String> depsStringList =  stringDepsStream.collect(Collectors.toList());

这一行提出了问题：

Stream<String> stringDepsStream = depsStream.map(Dependency::getArtifactId);

看起来这个用例很适合 Collectors or stream 文档中的示例。有什么明显的我错过了吗？

Answer 1

您使用的 maven-plugin-plugin 版本太旧。堆栈跟踪显示您正在使用 3.2 版，该版本 released in 2012. It depends on plugin-tools 3.2 which depends on ASM Core 3.3.1 于 2011 年发布。

这些早于 Java 8 (2014)，无法理解 method-references 和 lambda。

将您的 Maven/maven-plugin-plugin 版本升级到更新的版本，使其与您正在使用的 Java 版本兼容。

Stream map如何导致index out of bounds错误

How does Stream map leads to a index out of bounds error

java

lambda

maven-plugin

java-bytecode-asm

indexoutofboundsexception