Java 异常

异常架构图

The class Exception and any subclasses that are not also subclasses of RuntimeException are checked exceptions.

RuntimeException

Java 常见 RuntimeException：

• ArithmeticException
• ClassCastException
• ConcurrentModificationException
• NullPointerException
• IndexOutOfBoundsException

Exception

常见 Checked Exception：

• InterruptedException
• IOException
• SQLException

NoClassDefFoundError vs ClassNotFoundException

当应用程序运行的过程中尝试使用类加载器去加载 Class 文件的时候，如果没有在 classpath 中查找到指定的类，就会抛出ClassNotFoundException。一般情况下，当我们使用 Class.forName() 或者 ClassLoader.loadClass 以及使用ClassLoader.findSystemClass() 在运行时加载类的时候，如果类没有被找到，那么就会导致 JVM 抛出ClassNotFoundException。

NoClassDefFoundError

Thrown if the Java Virtual Machine or a ClassLoader instance tries to load in the definition of a class (as part of a normal method call or as part of creating a new instance using the new expression) and no definition of the class could be found.

The searched-for class definition existed when the currently executing class was compiled, but the definition can no longer be found.