D:\HeimaIT\Programme\java\bin\java.exe "-javaagent:D:\heima\IntelliJ IDEA 2021.2.1\lib\idea_rt.jar=62349:D:\heima\IntelliJ IDEA 2021.2.1\bin" -Dfile.encoding=UTF-8 -classpath D:\HeimaIT\OtherData\lycode\javaee\out\production\MyFile-IO homework.Demo8 Exception in thread "main" java.lang.NullPointerException at homework.Demo8.serachFile(Demo8.java:35) at homework.Demo8.serachFile(Demo8.java:37) at homework.Demo8.serachFile(Demo8.java:37) at homework.Demo8.main(Demo8.java:19)

时间: 2023-08-26 17:19:02 浏览: 33
这段代码运行时发生了`NullPointerException`异常，该异常通常表示尝试使用空对象的属性或方法。根据错误信息可以看出，异常发生在`Demo8`类的`serachFile()`方法的第35行，也就是说在访问某个对象的属性或方法时，该对象为空。可能是在遍历文件夹时，某个子文件夹的引用为空，导致了空指针异常。可以在代码中加入空判断来避免该异常。另外，在递归调用自己的时候，应该传入子文件夹的引用，而不是传入文件的引用。
相关问题

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: Index 5 out of bounds for length 1 at programme2.test1.main(test1.java:26)怎么改错

这是一个程序错误，需要检查程序中数组的长度和索引是否匹配。在这个特定的情况下，程序试图访问一个长度为1的数组的第六个元素，因此会报“ArrayIndexOutOfBoundsException”错误。需要修改程序代码，使其符合数组长度和索引的匹配要求。具体需要查看程序的代码，以确定哪里出了问题。

how does the programme following work:os.system("cls" if os.name == "nt" else "clear")

This program uses the os.system function to clear the console screen. The function takes a command as a parameter and executes it in the command prompt. The command being executed is "cls" if the operating system is Windows (nt stands for "New Technology") and "clear" if it is Unix-based (such as Linux or macOS). This is because the command to clear the screen in the command prompt is different for these two types of systems. So, this code checks the operating system being used and then executes the appropriate command to clear the console screen.

相关推荐

rar

java-programme-test.rar_doc_java练习

java 编程练习题，文件格式为doc格式
zip

java_chat_programme.zip_java

实现了简单的聊天功能。使用java实现。
zip

projet_poo_avancesM1:Java FX应用程序

Le programme recupère la TVA sur un serveur lors des achats d'articles Clonez le service web avec ce lien: https://github.com/kouassives/ServiceWeb_Projet_MASTER1.git et deployé le Serveur en vous...

npm err! code 1 npm err! path e:\software\programme\vue\vite\project\nf-bbs\

这是一个报错信息，说明在使用 npm 命令时出现了错误，错误代码为 1。另外，错误路径是在 e:\software\programme\vue\vite\project\nf-bbs 目录下。 这个错误信息可能涉及到以下几个方面： 1. npm 的安装问题。在...

11.写出执行abc.sh文件的命令以及执行后的结果：文件名：abc.sh#!/bin/bash shell类型#a simple shell script example#a functionfunciton sayhello() 函数{echo "Enter Your name:"read name 读取来自键盘输入的变量echo "Hello $name"}echo "programme starts here..." 主过程sayhelloecho "programme ends."

执行abc.sh文件的命令是：./abc.sh 执行后的结果是： programme starts here... Enter Your name: [在这里输入你的名字，比如"Tom"] Hello Tom programme ends.

ProgramModelEntities = _migrateRepository.GetAllWithNoTrackingAsync().ToList(); Programmes = ProgramModelEntities.Select(program => { CProgramme p = new CProgramme() { Id = new Guid(program.Id), Name = program.Name, SchoolId = SQIConstants.SYS_School_ID, Description = program.Description, CreatedById = String.IsNullOrEmpty(program.CreatedBy) ? new Guid("e306ca07-a21b-40fd-935a-343cfe369001") : new Guid(program.CreatedBy), CreatedTime = program.CreatedOn == null ? new DateTime().Ticks : program.CreatedOn.Value.Ticks, ModifiedById = String.IsNullOrEmpty(program.ModifiedBy) ? new Guid("e306ca07-a21b-40fd-935a-343cfe369001") : new Guid(program.ModifiedBy), ModifiedTime = program.ModifiedOn == null ? new DateTime().Ticks : program.ModifiedOn.Value.Ticks, Duration = 1 }; if (!String.IsNullOrEmpty(program.ProgramAdmins)) { var admins = program.ProgramAdmins.Split(";"); ResourceAccesses.Add(admins.Select(admin => new CResourceAccess() { Id = Guid.NewGuid(), UserId = new Guid(admin), RoleType = RoleType.ProgrammeAdmin, ResourceId = new Guid(program.Id), ResourceLevel = ResourceLevel.Programme } ).ToList()); } ResourcesList.Add(new CResources { Id = new Guid(program.Id), ResourceLevel = ResourceLevel.Programme, SchoolId = SQIConstants.SYS_School_ID, ProgrammeId = new Guid(program.Id), }); return p; } ).ToList(); 优化下这段代码

2. 使用 LINQ 的 Select 方法来进行对象的转换，可以让代码更简洁易读。例如，可以使用如下的代码替代 ProgramModelEntities.Select()： Programmes = await _migrateRepository.GetAllWithNoTrackingAsync()...

Use java to create a new class that reads the conversation.txt line by line and prints it to the console. In this class you should implement two different methods to read the file:1. Implement a method using a Scanner that reads the file2. Implement a method that uses a BufferedReader to read the file.Finally, alter the second method that reads the file line by line using a BufferedReader. After printing the first two lines, make your programme wait for the user to press enter before printing the next two lines. Continue this until all the lines are printed. Once the end of the file is reached, the programme should terminate so that when the user presses enter again, nothing bad happens.

// Method 1: Using Scanner to read file File file = new File("conversation.txt"); Scanner scanner = new Scanner(file); while (scanner.hasNextLine()) { System.out.println(scanner.nextLine()); } ...

Create a new class that reads the conversation.txt line by line and prints it to the console. In this class you should implement two different methods to read the file: 1. Implement a method using a Scanner that reads the file. (Successfully printing file content to Console: 1P) 2. Implement a method that uses a BufferedReader to read the file. (Successfully printing file content to Console: 1P) Finally, alter the second method that reads the file line by line using a BufferedReader. After printing the first two lines, make your programme wait for the user to press enter before printing the next two lines. Continue this until all the lines are printed. Once the end of the file is reached, the programme should terminate so that when the user presses enter again, nothing bad happens.

if (lineNumber % 2 == 0) { paused = true; } if (paused) { System.out.print("Press enter to continue..."); System.in.read(); paused = false; } } } catch (IOException e) { e.printStackTrace()...

Il s’agit d’un anneau de communication. Écrire un programme MPI où parmi n processus, le processus de rang r reçoit la valeur 1000 + (r − 1) du processus de rang r − 1, 1 ≤ r ≤ n − 1, et où le processus de rang 0 reçoit la valeur 1000 + (n − 1) du processus de rang n − 1

Voici un exemple de programme MPI en C qui implémente l'anneau de communication décrit dans votre question : c #include <mpi.h> #include <stdio.h> int main(int argc, char** argv) { int rank, ...

The programme should have the following features: ● A menu including Open and Exit where Open starts a JFileChooser to select the file with the questions inside and Exit ends the programme. ● Once a file is loaded, the GUI should display one question and its answers at a time. ● The user should be able to select an answer and they should be informed if they were correct or not. ● The user should be made aware of the number of correctly answered and the total number of questions answered. ● The user should only be able to proceed to the next question once they answered the current one. ● Once all questions have been answered, the user should be informed of their overall score and that the game has finished. The Open menu item should now be enabled to start a new quiz. Optionally, you can add a restart menu item to redo the current quiz. Concrete sub-tasks: a) define a class called Question to hold a single question, i.e. the text, the possible answers, and the correct answer index; (0.25P) b) write a method to select a file via a JFileChooser and to read all the questions from that file into an array/list of Question objects (assume that file has the structure mentioned above); (0.25P) c) design and implement a GUI with the components mentioned above: A menu, ability to display the question and answers, ability to select an answer, show the outcome and score, and proceed to the next question. (Appropriate layout: 1P, Class extends JFrame: 0.25P, Class follows OOP principles: 0.25P, Global set-up in main method: 0.25P)1 d) write a method to display a question on the GUI you designed; (0.25P) e) implement an actionPerformed method to respond to user interactions with the GUI. Make sure to enable and disable interactive components as required, e.g. the user should not be able to skip to the next question without selecting an answer first and they should not be able to load a new quiz before finishing the current one;

self.answer_2_button.setText(current_question.answers[1]) self.answer_3_button.setText(current_question.answers[2]) self.answer_4_button.setText(current_question.answers[3]) self.answers_button_...

Soit A une matrice carrée réelle de taille (n, n) diagonale par blocs. Écrire un programme MPI où on affecte à chaque processus de rang r un bloc diagonal de taille p dont tous les coefficients ont pour valeur r, chaque processus de rang r calcule sa trace locale. Le processus de rang 0 récupère toutes les traces locales pour calculer la trace globale de la matrice. Soit np le nombre de processus. NB : La trace d’une matrice A est la somme des éléments diagonaux de A.

Voici une implémentation MPI en C pour résoudre le problème décrit : c #include <mpi.h> #include <stdio.h> #include <stdlib.h> #define N 8 // taille de la matrice carrée #define P 2 // ...

sentinel-1卫星介绍

Sentinel-1是欧空局(European Space Agency, ESA)推出的一款C波段合成孔径雷达(Synthetic Aperture Radar, SAR)卫星，于2014年4月成功发射。它是欧洲地球观测计划(Copernicus Programme)的一部分，旨在提供全球覆盖...

Finally, alter the second method that reads the file line by line using a BufferedReader. After printing the first two lines, make your programme wait for the user to press enter before printing the next two lines. Continue this until all the lines are printed. Once the end of the file is reached, the programme should terminate so that when the user presses enter again, nothing bad happens. Hint: You can use a Scanner which reads from the system input stream like this Scanner s = new Scanner(System.in); to wait for user input.

if (lineCount < 2) { System.out.println(line); lineCount++; } else { System.out.println(line); Scanner scanner = new Scanner(System.in); scanner.nextLine(); // waits for user to press enter ...

You are required to write a C program to: • Initialize GPIO peripherals • Initialise UART peripheral for receiving ASCII characters ‘A’ to ‘Z’ at baud 9600 • Initialise an internal array to hold 10 characters with head and tail: CharBuff • Repeat the following: o When data is received on the serial communication port, read ASCII character X, o If received character X is a capital letter add it to CharBuff, else ignore. o While CharBuff is not empty, transmit the morse code of the oldest stored character by blinking the LED (code provided for you). o When CharBuff is full, disable UART RX. o If UART RX is disabled, pushing the button P_B1 will activate it; otherwise, pushing the button does not affect your programme. You are recommended to use interrupt to control UART receiving data and coordinate the operation between CharBuff and P_LD2.

".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..", ".---", "-.-", ".-..", "--", "-.", "---", ".--.", "--.-", ".-.", "...", "-", "..-", "...-", ".--", "-..-", "-.--", "--.." }; // ...

use Java to achieve:A GUI-based program is required that will enable people to take a test from a bank of multiple choice questions. Each question consists of: ● the question text; ● 4 possible answers; ● the number of the correct answer (1-4, not 0-3); Questions are held sequentially in a text file with each question held on 6 consecutive lines. An example entry in the questions text file could look like this: What is your favourite colour? Red Green Blue Pink 4 How many Harry Potter books are there? 5 6 7 8 3 The programme should have the following features: ● A menu including Open and Exit where Open starts a JFileChooser to select the file with the questions inside and Exit ends the programme. ● Once a file is loaded, the GUI should display one question and its answers at a time. ● The user should be able to select an answer and they should be informed if they were correct or not. ● The user should be made aware of the number of correctly answered and the total number of questions answered. ● The user should only be able to proceed to the next question once they answered the current one. ● Once all questions have been answered, the user should be informed of their overall score and that the game has finished. The Open menu item should now be enabled to start a new quiz. Optionally, you can add a restart menu item to redo the current quiz.

String[] answers = {parts[1], parts[2], parts[3], parts[4]}; int correctAnswer = Integer.parseInt(parts[5]); questionList.add(new Question(questionText, answers, correctAnswer)); } ...
zip

Projet-Java-Programme-des-festivals-de-musique-summer-2015:2014-2015 年 IUT de Vélizy S2 项目结束

Project-Java-Program-des-festivals-de-musique-summer-2015 2014-2015 年 IUT de Vélizy S2 项目结束
zip

BatailleFantastique:在 LSI2 中为 ENSSAT 执行的 Java 项目

绝地求生在 LSI2 中为 ENSSAT 执行的 Java 项目==================== 计划启动 Pour lancer le programme de Bataille Fantastique, il suffit de double-cliquer sur "BatailleFantastique.jar"Si cette méthode ...

最新推荐

recommend-type

yolov5-face-landmarks-opencv

yolov5检测人脸和关键点，只依赖opencv库就可以运行，程序包含C++和Python两个版本的。 本套程序根据https://github.com/deepcam-cn/yolov5-face 里提供的训练模型.pt文件。转换成onnx文件， 然后使用opencv读取onnx文件做前向推理，onnx文件从百度云盘下载，下载 链接：https://pan.baidu.com/s/14qvEOB90CcVJwVC5jNcu3A 提取码：duwc 下载完成后，onnx文件存放目录里，C++版本的主程序是main_yolo.cpp，Python版本的主程序是main.py 。此外，还有一个main_export_onnx.py文件，它是读取pytorch训练模型.pt文件生成onnx文件的。 如果你想重新生成onnx文件，不能直接在该目录下运行的，你需要把文件拷贝到https://github.com/deepcam-cn/yolov5-face 的主目录里运行，就可以生成onnx文件。
recommend-type

setuptools-0.6c8-py2.5.egg

文件操作、数据分析和网络编程等。Python社区提供了大量的第三方库，如NumPy、Pandas和Requests，极大地丰富了Python的应用领域，从数据科学到Web开发。Python库的丰富性是Python成为最受欢迎的编程语言之一的关键原因之一。这些库不仅为初学者提供了快速入门的途径，而且为经验丰富的开发者提供了强大的工具，以高效率、高质量地完成复杂任务。例如，Matplotlib和Seaborn库在数据可视化领域内非常受欢迎，它们提供了广泛的工具和技术，可以创建高度定制化的图表和图形，帮助数据科学家和分析师在数据探索和结果展示中更有效地传达信息。
recommend-type

5-3.py

5-3
recommend-type

Java八股文.pdf

"Java八股文"是一个在程序员社群中流行的术语，特别是在准备技术面试时。它指的是一系列在Java编程面试中经常被问到的基础知识点、理论概念和技术细节。这个术语的命名来源于中国古代科举考试中的“八股文”，一种具有固定格式和套路的文章形式。 在Java编程的上下文中，"Java八股文"通常包括以下几个方面："Java八股文"是一个在程序员社群中流行的术语，特别是在准备技术面试时。它指的是一系列在Java编程面试中经常被问到的基础知识点、理论概念和技术细节。这个术语的命名来源于中国古代科举考试中的“八股文”，一种具有固定格式和套路的文章形式。 在Java编程的上下文中，"Java八股文"通常包括以下几个方面："Java八股文"是一个在程序员社群中流行的术语，特别是在准备技术面试时。它指的是一系列在Java编程面试中经常被问到的基础知识点、理论概念和技术细节。这个术语的命名来源于中国古代科举考试中的“八股文”，一种具有固定格式和套路的文章形式。 在Java编程的上下文中，"Java八股文"通常包括以下几个方面："Java八股文"是一个在程序员社群中流行的术语，特别是在准备技术面试时。它
recommend-type

麦肯锡咨询顾问必备宝典.ppt

麦肯锡咨询顾问必备宝典.ppt
recommend-type

zigbee-cluster-library-specification

最新的zigbee-cluster-library-specification说明文档。
recommend-type

管理建模和仿真的文件

管理Boualem Benatallah引用此版本：布阿利姆·贝纳塔拉。管理建模和仿真。约瑟夫-傅立叶大学-格勒诺布尔第一大学，1996年。法语。NNT：电话：00345357HAL ID：电话：00345357https://theses.hal.science/tel-003453572008年12月9日提交HAL是一个多学科的开放存取档案馆，用于存放和传播科学研究论文，无论它们是否被公开。论文可以来自法国或国外的教学和研究机构，也可以来自公共或私人研究中心。L’archive ouverte pluridisciplinaire
recommend-type

实现实时数据湖架构：Kafka与Hive集成

![实现实时数据湖架构：Kafka与Hive集成](https://img-blog.csdnimg.cn/img_convert/10eb2e6972b3b6086286fc64c0b3ee41.jpeg) # 1. 实时数据湖架构概述** 实时数据湖是一种现代数据管理架构，它允许企业以低延迟的方式收集、存储和处理大量数据。与传统数据仓库不同，实时数据湖不依赖于预先定义的模式，而是采用灵活的架构，可以处理各种数据类型和格式。这种架构为企业提供了以下优势： - **实时洞察：**实时数据湖允许企业访问最新的数据，从而做出更明智的决策。 - **数据民主化：**实时数据湖使各种利益相关者都可
recommend-type

2． 通过python绘制y=e-xsin(2πx)图像

可以使用matplotlib库来绘制这个函数的图像。以下是一段示例代码： ```python import numpy as np import matplotlib.pyplot as plt def func(x): return np.exp(-x) * np.sin(2 * np.pi * x) x = np.linspace(0, 5, 500) y = func(x) plt.plot(x, y) plt.xlabel('x') plt.ylabel('y') plt.title('y = e^{-x} sin(2πx)') plt.show() ``` 运行这段
recommend-type

JSBSim Reference Manual

JSBSim参考手册，其中包含JSBSim简介，JSBSim配置文件xml的编写语法，编程手册以及一些应用实例等。其中有部分内容还没有写完，估计有生之年很难看到完整版了，但是内容还是很有参考价值的。