The abnormal treatment in the Java class library and the Holmes box

The abnormal processing and Holmes framework in the Java class library introduction: When writing a Java application, abnormal processing is a very important aspect.When the application is errors or abnormal during execution, a mechanism is required to deal with these abnormalities and take appropriate measures.The Java class library provides a rich set of abnormal processing mechanisms that enable developers to capture, handle and report abnormalities. text: Abnormal processing is an important part of the Java program design. The abnormal processing mechanism in the Java class library is achieved through a series of class and interfaces.Among them, the most basic class is the Throwable class, which is the base class of the abnormal system.The Throwable class derives two subclasses: Error and Exception.Error means serious errors and usually cannot recover.Exception indicates the abnormality that can be processed by the program. Java provides a series of abnormal categories for specific types of abnormalities.These abnormal classes are inherited from the Exception class.For example: -Nullpointerexception: The exception thrown when using an empty object in the application. -Arrayindexoutofboundsexception: exceptions that are thrown out of the valid range when accessing an array. -IOEXCEPTION: The abnormality thrown when an error occurs in the input and output operation. The abnormal processing mechanism in the Java class library mainly depends on the TRY-CATCH block to achieve.Developers can write codes that may occur in TRY blocks, and then use CATCH blocks to capture and handle abnormalities.For example: try { // code block may throw out abnormal logic } catch (ExceptionType1 e) { // Processing ExceptionType1's abnormal logic } catch (ExceptionType2 e) { // Processing ExceptionType2's abnormal logic } finally { // The code block that will always execute is used to clean the resources } CATCH blocks can appear multiple times to deal with different types of abnormalities.In the CATCH block, developers can write corresponding abnormal processing logic according to the specific abnormal type.Finally block is used to specify some code that will be executed, which is often used to clean up resources. In addition to the Try-Catch block, Java also provides Throws keywords, allowing developers to declare the abnormalities that may be thrown on the method in order to call the code for the code correctly.For example: public void readFile() throws IOException { // Read the code of the file } In the Java library, abnormal processing is closely related to the Holmes framework.Holmes is a Java class library aims to provide a more simplified abnormal processing mechanism.The Holmes framework provides developers with a way to declare abnormal processing logic. It uses the form of annotation and method chain to make the abnormal processing code more concise and easy to read. Below is an example of using the Holmes framework: @Catch(value=IOException.class, handler=MyExceptionHandler.class) public void readFile() throws IOException { // Read the code of the file } In the above code, the @catch annotation is used to declare abnormal processing logic.Among them, the value attribute specifies the abnormal type to be captured, and the handler attribute specifies the class that is used to handle abnormalities.In this way, there is no need to write the TRY-CATCH block in the method body, and the abnormalities will be automatically captured and called the corresponding processing class treatment abnormality by the Holmes framework. in conclusion: The Java class library provides a wealth of abnormal processing mechanisms, allowing developers to capture, handle and report abnormalities.The abnormal processing uses the TRY-CATCH block and the Throws keywords, which can write corresponding processing logic according to the specific types of abnormalities.In addition, the Holmes framework provides a more simplified way to deal with abnormal processing, using annotations and method chains to declare abnormal processing logic, making the abnormal processing code more concise and easy to read. Reference materials: -ORACLE official document: https://docs.oracle.com/en/java/javase/14/docs/api/java.base/java/langable.html -Holmes github warehouse: https://github.com/dovamir/holmes