Detailed explanation of the abnormal processing mechanism in Java core framework
Detailed explanation of the abnormal processing mechanism in Java core framework
Abnormal treatment is a very important part of Java programming.Java provides a strong set of abnormal processing mechanisms that allow developers to more flexibly handle various errors in the program.This article will explain the abnormal processing mechanism in the Java core framework in detail and explain the Java code example.
1. Definition and classification of abnormalities
Abnormality is an error or abnormal situation that may occur during the program running.The abnormalities in Java can be divided into two types: Check Exceptions and unchecked exceptions.
Examination exceptions refer to abnormalities that must be manifested in the process of program writing, including IOEXception, SQLEXception, etc.If you do not declare that you can check the exception in the method signature, or if you do not capture in the TRY-CATCH block, the compiler will report an error.
Unscooable abnormalities refer to errors during the running process. They are generally caused by program errors or environmental problems, such as NullPointerexception, array of array, ArrayExoutofboundsexception, etc.These abnormalities are instances of Runtimeexception and its subclasses, and the compiler will not force them to deal with them.
2. The syntax of abnormal treatment
The abnormal treatment in Java is based on three keywords: TRY, Catch, and Finally.TRY block contains code that may be thrown out. The CATCH block is used to capture and process abnormalities. Finally blocks are used to perform code that must be executed regardless of whether or not abnormalities occur.
The following is a simple Java code example, demonstrating the grammar of the abnormal processing:
try {
// Perhaps abnormal code
int Result = 10 /0; // Except 0 will throw an Arithmeticexception
} catch (ArithmeticException e) {
// Capture and handle abnormalities
System.out.println ("" Except for the abnormal operation of the method: " + e.getMessage ());
} finally {
// Whether or not an abnormal code will be executed
System.out.println ("" Odomy complete ");
}
In the above example, the division of the TRY block will throw an arithmetic abnormality. Catch block captures and handles the exception. The code in the final block will be executed regardless of whether or not it occurs.
3. Throw abnormality
In Java, you can use the Throw keyword to throw an exception manually.Under normal circumstances, when a certain condition is not met, you can use a Throw statement to throw an exception to interrupt the normal execution process of the program.
The following is an example. Demonstration of how to manually throw a custom abnormality:
public class CustomException extends Exception {
public CustomException(String message) {
super(message);
}
}
public class Example {
public static void main(String[] args) {
try {
// Check the condition
boolean condition = false;
if (!condition) {
// Throw abnormality when the condition is not satisfied
Throw New CustomException ("Insufficient conditions");
}
} catch (CustomException e) {
System.out.println ("Capture to custom abnormalities:" + e.getMessage ());
}
}
}
In the above example, when the conditions are not met, throw a custom abnormality CustomException and capture and handle the exception in the CATCH block.
4. Delivery
In Java, if a method is thrown out of an abnormality but not processed, the caller of the current method must also perform abnormal processing, otherwise it will continue to pass to the upper method until there are corresponding abnormal processing code.This abnormal transmission mechanism is called an abnormal chain.
The following is an example that demonstrates the abnormal transmission mechanism:
public class Example {
public static void main(String[] args) {
try {
method1();
} catch (Exception e) {
System.out.println ("Capture abnormal:" + e.getMessage ());
}
}
public static void method1() throws Exception {
method2();
}
public static void method2() throws Exception {
// Throw an exception
Throw New Exception
}
}
In the above example, the Method2 method thrown an exception, but did not process it.Therefore, abnormalities will be passed to the Method1 method, and then passed to the Main method for processing.
Summarize
The abnormal processing mechanism in the Java core framework provides an effective way to handle errors that may occur in the program.Developers can use Try-Catch-Finally grammar capture, processing and release resources to improve the reliability and robustness of the program.At the same time, by throwing an exception, the normal execution process of the program can be interrupted, so that the error information can be passed and processed.Understanding and using the Java abnormal processing mechanism is very important for writing high -quality Java programs.
