我已经研究了这个问题的各种答案。它们都不起作用。
我有以下代码：

import java.util.Properties;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.FileNotFoundException;
import java.io.IOException;

public class ApplicationConfig {

    private static Logger LOG;

    private String appConfigFileLocation = "application.properties"; 
    private Properties appConfig;

    private static ApplicationConfig instance;

    public static ApplicationConfig getInstance() {
        if(instance == null) {
            instance = new ApplicationConfig();
        }

        return instance;
    } 

    private ApplicationConfig() {
        LOG = LoggerFactory.getLogger(this.getClass().getSimpleName());

        appConfig = new Properties();

        try {
            LOG.info("Reading config from " + appConfigFileLocation);

            appConfig.load(ClassLoader.getSystemResourceAsStream(appConfigFileLocation));

            LOG.info("Done reading config from " + appConfigFileLocation);
        } catch (FileNotFoundException e) {
            LOG.error("Encountered FileNotFoundException while reading configuration: " + e.getMessage());
            throw new RuntimeException(e);
        } catch (IOException e) {
            LOG.error("Encountered IOException while reading configuration: " + e.getMessage());
            throw new RuntimeException(e);
        }
    }
}

我创建了一个jar文件。jar文件 application.properties 从根本上说。我还复制了 application.properties 文件输入 /etc/hadoop/conf 而在 target/classes/ 目录。
我使用 hadoop jar 命令来执行代码。
但我一直得到一个错误： java.lang.NullPointerException at java.util.Properties$LineReader.readLine(Properties.java:434) 请帮助我解决这个令人沮丧的错误！