try with resources子句中的异常

Question

class Demo
{
    public static void main(String args[]) throws java.io.IOException
    {
        try(FileInputStream fin = new FileInputStream("Demo.txt"))
        {
            //This block is executed successfully
        }

        System.out.println("Will it be executed if error occurs in try clause");
    }
}

假设try block中的代码如代码中所述成功执行，而exception中出现了try with resource clause，这意味着auto closing文件中出现异常。

如何处理try with resource clause中的异常？

我想问的是，该异常会被抛到JVM并且会突然终止我的程序并且println语句不会被执行吗？

我可以捕获该异常，以便还可以执行剩余的程序吗？

Answer 1

如果close的{​​{1}}方法抛出异常，则在AutoClosable块执行后确实会抛出异常。

如果需要处理异常，只需在try子句中添加一个catch子句即可。

以下代码说明了行为：

try

它使用堆栈跟踪终止JVM：

public class Foo {

    public static class Bar implements AutoCloseable {

        @Override
        public void close() {
            throw new RuntimeException();
        }

    }

    public static void main(String args[]) {
        try (Bar b = new Bar()) {
            // This block is executed successfully
        }

        System.out.println("Will it be executed if error occurs in try clause");
    }
}

25是我的Exception in thread "main" java.lang.RuntimeException at test3.Foo$Bar.close(Foo.java:14) at test3.Foo.main(Foo.java:25) 子句的结束}所在的行。

可以使用以下方式处理：

try

Answer 2

只添加catch子句，以捕获异常，否则程序将被终止

public static void main(String[] args) throws FileNotFoundException, IOException {
        try(FileInputStream fin = new FileInputStream("Demo.txt"))
        {
            //This block is executed successfully
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        System.out.println("Will it be executed if error occurs in try clause");
    }

Answer 3

我认为最后程序的其余部分将会运行，请尝试并报告。

课程演示

{
    public static void main(String args[]) throws java.io.IOException
    {
        try(FileInputStream fin = new FileInputStream("Demo.txt"))
        {
            //This block is executed successfully
        } finally {
           System.out.println("Will it be executed if error occurs in try clause");
        }
    }
}

Answer 4

只需删除文件Demo.txt并运行以下代码。

抛出此类异常的最简单方法是运行此代码，没有现有资源（在本例中为Demo.txt）：

public static void main(String args[])
    {
        try(FileInputStream fin = new FileInputStream("Demo.txt"))
        {

        } catch(IOException exc) {
            System.out.println("An exception has occured. Possibly, the file does not exist. " + exc);
        }

        System.out.println("Will it be executed if error occurs in try clause");
    }