与getClassLoader()方法有关的问题：为什么下面的代码中会发生空指针异常

Question

import java.io.IOException; import java.util.Properties; public class PropertyUtil { public static void main(String[] args) { Properties properties = new Properties(); try { properties.load(PropertyUtil.class.getClassLoader().getResourceAsStream("LYZ.properties")); String username = properties.getProperty("username"); System.out.println(username); } catch (IOException e) { System.out.println("无法读取LYZ.properties"); } } } 控制台信息 Exception in thread "main" java.lang.NullPointerException at java.util.Properties$LineReader.readLine(Properties.java:434) at java.util.Properties.load0(Properties.java:353) at java.util.Properties.load(Properties.java:341) at com.test.PropertyUtil.main(PropertyUtil.java:10) 第十行代码就是: properties.load(PropertyUtil.class.getClassLoader().getResourceAsStream("LYZ.properties"));