小编ken*_*eno的帖子

我已经实现了一种方法,它只是循环一组包含许多不同模块数据的CSV文件.然后将'moduleName'添加到hashSet中.(代码如下所示)

我使用了一个hashSet,因为它保证不会插入重复项而不是ArrayList,它必须使用contains()方法并遍历列表以检查它是否已存在.

我相信使用哈希集具有比数组列表更好的性能.我说的是正确的吗？

还有,有人可以向我解释一下:

1. 如果使用,如何处理每个数据结构的性能？

2. 使用big-O表示法的复杂性是多少？

   HashSet<String> modulesUploaded = new HashSet<String>();
   
   for (File f: marksheetFiles){
       try {
           csvFileReader = new CSVFileReader(f);
           csvReader = csvFileReader.readFile();
           csvReader.readHeaders();
   
           while(csvReader.readRecord()){
               String moduleName = csvReader.get("Module");
   
               if (!moduleName.isEmpty()){
                   modulesUploaded.add(moduleName);
               }
           }
   
       } catch (IOException e) {
           e.printStackTrace();
       }
   
       csvReader.close();
   }
   return modulesUploaded; 
   

   Run Code Online (Sandbox Code Playgroud)

   }

当我尝试在模拟器中运行我的应用程序时，它可以正常运行，但是当我尝试构建应用程序错误时...

错误图片：

org.gradle.execution.MultipleBuildFailures: Build completed with 1 failures.
    at org.gradle.initialization.DefaultGradleLauncher$ExecuteTasks.run(DefaultGradleLauncher.java:358)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:300)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:292)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:174)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:90)
    at org.gradle.internal.operations.DelegatingBuildOperationExecutor.run(DelegatingBuildOperationExecutor.java:31)
    at org.gradle.initialization.DefaultGradleLauncher.runTasks(DefaultGradleLauncher.java:219)
    at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:149)
    at org.gradle.initialization.DefaultGradleLauncher.executeTasks(DefaultGradleLauncher.java:124)
    at org.gradle.internal.invocation.GradleBuildController$1.call(GradleBuildController.java:77)
    at org.gradle.internal.invocation.GradleBuildController$1.call(GradleBuildController.java:74)
    at org.gradle.internal.work.DefaultWorkerLeaseService.withLocks(DefaultWorkerLeaseService.java:154)
    at org.gradle.internal.work.StopShieldingWorkerLeaseService.withLocks(StopShieldingWorkerLeaseService.java:38)
    at org.gradle.internal.invocation.GradleBuildController.doBuild(GradleBuildController.java:96)
    at org.gradle.internal.invocation.GradleBuildController.run(GradleBuildController.java:74)
    at org.gradle.tooling.internal.provider.runner.BuildModelActionRunner.run(BuildModelActionRunner.java:55)
    at org.gradle.launcher.exec.ChainingBuildActionRunner.run(ChainingBuildActionRunner.java:35)
    at org.gradle.launcher.exec.ChainingBuildActionRunner.run(ChainingBuildActionRunner.java:35)
    at org.gradle.tooling.internal.provider.ValidatingBuildActionRunner.run(ValidatingBuildActionRunner.java:32)
    at org.gradle.launcher.exec.RunAsBuildOperationBuildActionRunner$3.run(RunAsBuildOperationBuildActionRunner.java:50)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:300)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:292)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:174)
    at org.gradle.internal.operations.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:90)
    at org.gradle.internal.operations.DelegatingBuildOperationExecutor.run(DelegatingBuildOperationExecutor.java:31)
    at org.gradle.launcher.exec.RunAsBuildOperationBuildActionRunner.run(RunAsBuildOperationBuildActionRunner.java:45)
    at org.gradle.tooling.internal.provider.SubscribableBuildActionRunner.run(SubscribableBuildActionRunner.java:51)
    at org.gradle.launcher.exec.InProcessBuildActionExecuter$1.transform(InProcessBuildActionExecuter.java:47)
    at org.gradle.launcher.exec.InProcessBuildActionExecuter$1.transform(InProcessBuildActionExecuter.java:44)
    at org.gradle.composite.internal.DefaultRootBuildState.run(DefaultRootBuildState.java:79)
    at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:44)
    at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:30)
    at org.gradle.launcher.exec.BuildTreeScopeBuildActionExecuter.execute(BuildTreeScopeBuildActionExecuter.java:39)
    at org.gradle.launcher.exec.BuildTreeScopeBuildActionExecuter.execute(BuildTreeScopeBuildActionExecuter.java:25)
    at org.gradle.tooling.internal.provider.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:80)
    at org.gradle.tooling.internal.provider.ContinuousBuildActionExecuter.execute(ContinuousBuildActionExecuter.java:53) …