Java — различия между версиями

	/**
	 * The way I tried to use dealing with "file-reading" exceptions.
	 */
	public static void firstExample() {
		String filename = "filename"; 
		try {
			BufferedReader reader = new BufferedReader(new FileReader(filename));
			String line;
			try {
				while ((line = reader.readLine()) != null) {
					/*TODO something*/
					System.out.println(line);
				}
			} catch (IOException e) {
				System.err.println("Strange IOException happened during reading. Message: " + e.getMessage());
				e.printStackTrace();
			} finally {
				try {
					reader.close();
				} catch (IOException e) {
					System.err.println("Strange IOException happened during closing file. Message: " + e.getMessage());
					e.printStackTrace();
				}
			}
		} catch (FileNotFoundException e) {
			System.err.println("Couldn't find file: " + filename);
		}
	}

	/**
	 * The way to get rid of one level of try blocks. 
	 * Significantly reduces depth when dealing with several files. 
	 */
	public static void secondExample() {
		String filename = "filename"; 
		BufferedReader reader = null;
		try {
			reader = new BufferedReader(new FileReader(filename));
			String line;
			while ((line = reader.readLine()) != null) {
				/*TODO something*/
				System.out.println(line);
			}
		} catch (FileNotFoundException e) {
			System.err.println("Couldn't find file: " + filename);
		} catch (IOException e) {
			System.err.println("Strange IOException happened during reading. Message: " + e.getMessage());
			e.printStackTrace();
		} finally {
			if (reader != null) {
				try {
					reader.close();
				} catch (IOException e) {
					System.err.println("Strange IOException happened during closing file. Message: " + e.getMessage());
					e.printStackTrace();
				}
			}
		}
	}

	/**
	 * Brand new Java7 way of dealing with this example.
	 * Uses try-with-resources statement.
	 * For more information see: 
	 * http://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html
	 * Remark: some exceptions that you dealt with in two previous examples might be suppressed here.
	 */
	public static void thirdExample() {
		String filename = "filename"; 
		try (BufferedReader reader = new BufferedReader(new FileReader(filename))) {
			String line;
			while ((line = reader.readLine()) != null) {
				/*TODO something*/
				System.out.println(line);
			}
		} catch (FileNotFoundException e) {
			System.err.println("Couldn't find file: " + filename);
		} catch (IOException e) {
			System.err.println("Strange IOException happened. Message: " + e.getMessage());
			e.printStackTrace();
		} 
	}