1. checked exception:
These are exceptional conditions that a well-written application should anticipate and recover from. Example:suppose an application prompts a user for an input file name, then opens the file by passing the name to the constructor for
Checked exceptions are subject to the Catch or Specify Requirement. All exceptions are checked exceptions, except for those indicated by
2. error:
These are exceptional conditions that are external to the application, and that the application usually cannot anticipate or recover from.
Example: suppose that an application successfully opens a file for input, but is unable to read the file because of a hardware or system malfunction. The unsuccessful read will throw
Errors are not subject to the Catch or Specify Requirement. Errors are those exceptions indicated by
These are exceptional conditions that a well-written application should anticipate and recover from. Example:suppose an application prompts a user for an input file name, then opens the file by passing the name to the constructor for
java.io.FileReader. Normally, the user provides the name of an existing, readable file, so the construction of the FileReader object succeeds, and the execution of the application proceeds normally. But sometimes the user supplies the name of a nonexistent file, and the constructor throws java.io.FileNotFoundException Checked exceptions are subject to the Catch or Specify Requirement. All exceptions are checked exceptions, except for those indicated by
Error, RuntimeException, and their subclasses.2. error:
These are exceptional conditions that are external to the application, and that the application usually cannot anticipate or recover from.
Example: suppose that an application successfully opens a file for input, but is unable to read the file because of a hardware or system malfunction. The unsuccessful read will throw
java.io.IOError. An application might choose to catch this exception, in order to notify the user of the problem — but it also might make sense for the program to print a stack trace and exit.Errors are not subject to the Catch or Specify Requirement. Errors are those exceptions indicated by
Error and its subclasses.3.runtime exception:
These are exceptional conditions that are internal to the application, and that the application usually cannot anticipate or recover from. These usually indicate programming bugs, such as logic errors or improper use of an API.
Example: consider the application described previously that passes a file name to the constructor for
FileReader. If a logic error causes a null to be passed to the constructor, the constructor will throw NullPointerException. The application can catch this exception, but it probably makes more sense to eliminate the bug that caused the exception to occur.
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