try-catch-finally的使用?

使用try-catch-finally关闭资源情况

//读取⽂本⽂件的内容
Scanner scanner = null;
try {
    scanner = new Scanner(new File("D://read.txt"));
    while (scanner.hasNext()) {
        System.out.println(scanner.nextLine());
    }
} catch (FileNotFoundException e) {
    e.printStackTrace();
} 
finally {
    if (scanner != null) {
        scanner.close();
    }
}

使用try-with-resources关闭资源情况

声明单个资源要关闭的情况:

try ( Scanner scanner = new Scanner(new File("test.txt")) ) {   
    while (scanner.hasNext()) {
        System.out.println(scanner.nextLine());
    }
} catch (FileNotFoundException e) {
    e.printStackTrace();
} 

声明多个资源要关闭情况:

try (
    BufferedInputStream bin = new BufferedInputStream(new FileInputStream(new File("test.txt"))); 
    BufferedOutputStream bout = new BufferedOutputStream(new FileOutputStream(new File("out.txt")))
) {
    int b;
    while ((b = bin.read()) != -1) {
        bout.write(b);
    }
}
catch (IOException e) {
    e.printStackTrace();
}