RealInteractiveUser.java

package io.airlift.airship.cli;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class RealInteractiveUser
        implements InteractiveUser
{
    @Override
    public boolean ask(String question, boolean defaultValue)
    {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        try {
            while (true) {
                System.out.print(question + (defaultValue ? " [Y/n] " : " [y/N] "));
                String line = null;
                try {
                    line = reader.readLine();
                }
                catch (IOException ignored) {
                }

                if (line == null) {
                    throw new IllegalArgumentException("Error reading from standard in");
                }

                line = line.trim().toLowerCase();
                if (line.isEmpty()) {
                    return defaultValue;
                }
                if ("y".equalsIgnoreCase(line) || "yes".equalsIgnoreCase(line)) {
                    return true;
                }
                if ("n".equalsIgnoreCase(line) || "no".equalsIgnoreCase(line)) {
                    return false;
                }
            }
        }
        finally {
            System.out.println();
        }
    }
}