为什么readLine（）没有阻塞？

Question

Given the following code, the first call to readLine() is not blocking, both "Enter name:" and "Enter address:" are printed at the same time, and address gets assigned to whatever is entered. Why? I've tried putting them in separate try blocks, getting rid of the loop and generally reordering things.

public class AddressReader {

public static void main(String[] args) {

    Path file = Paths.get("d:/java IO/addresses.txt");

    try {
        Files.createDirectories(file.getParent());
    } catch (IOException e) {
        System.err.println("Error craeting directory: " + file.getParent());
        e.printStackTrace();
        System.exit(1);
    }
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    int c = 0;
    try {
        System.out.println("<a>dd an entry or <r>ead entries");
        c = br.read();
    } catch (IOException e) {
        System.out.println("An error has occured, try again");
    }
    switch (c) {
    case 'a':
        String name = null;
        String address = null;

        while (name == null || name == "" || address == null || address == "") {
            try {
                System.out.println("Enter name:");
                name = br.readLine();
                System.out.println("Enter address:");
                address = br.readLine();
            } catch (IOException e) {
                System.out.println("An error has occured, try again");
            }
            System.out.println("name = " + name);
            System.out.println("address = " + address);
        }
        //writeEntry(file, name, address);
        break;
    case 'r':
        //readEntries(file);
        break;
    default:
        System.out.println("Invalid entry, try again.");
    }

}

}

Answer 1

This is because of this line:

c = br.read();

This does not consume the new-line character that is produced by pressing ENTER .

To solve this issue, use this instead:

c = br.readLine().charAt(0);

Answer 2

Over and above whats already been said, for what you're trying to do I suggest using the Console instead:

Console console = System.console();
String name = console.readLine("Create a name.");
char[] password = console.readPassword("Create a password.");
System.out.println(name + ":" + new String(password));