try-catch-finally statement in Java exception handling

The try-catch-finally statement in exception handling includes three parts: try block: contains code that may throw exceptions. catch block: catches and handles specific types of exceptions. finally block: Code that is always executed regardless of whether an exception occurs, often used to release resources.

The try-catch-finally statement in Java exception handling

Exception handling is an important concept in Java programming. When an exception occurs in the program, we can use the try-catch-finally statement to handle the exception.

try-catch statement

try-catch statement is used to catch exceptions. The syntax is as follows:

try {
    // 可能会抛出异常的代码
} catch (ExceptionName e) {
    // 捕获异常并处理
}

try block contains code that may throw an exception. If an exception occurs within the try block, control is transferred to the catch block that matches the exception type.

finally statement

The finally statement is used for code that is always executed after the try-catch statement block has completed execution. The syntax is as follows:

try {
    // 可能会抛出异常的代码
} catch (ExceptionName e) {
    // 捕获异常并处理
} finally {
    // 在任何情况下都会执行的代码
}

finally The code in the block will be executed when:

• try block executes successfully without throwing an exception.
• The try block throws an exception, and the exception is caught by the catch block.
• The try block throws an exception, but there is no corresponding catch block to catch it.

Practical case

The following is an example of using the try-catch-finally statement to handle file read exceptions:

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;

public class FileRead {

    public static void main(String[] args) {
        File file = new File("file.txt");

        try {
            Scanner scanner = new Scanner(file);
            while (scanner.hasNextLine()) {
                System.out.println(scanner.nextLine());
            }
        } catch (FileNotFoundException e) {
            System.out.println("文件不存在！");
        } finally {
            // 无论是否发生异常，都会关闭文件
            scanner.close();
        }
    }
}

In this In the example, the try block attempts to read the contents of the file "file.txt". If the file does not exist, a FileNotFoundException exception is thrown and caught by the catch block. The finally block is always executed and is used to close the file.

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