A static method which peeks into the java.io.Console class and manually turns on or off echoing in the given console. - Java Language Basics

Java examples for Language Basics:Console

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Description

A static method which peeks into the java.io.Console class and manually turns on or off echoing in the given console.

Demo Code

/*/*from   w  w  w . j  av  a2s .c  om*/
 * Copyright (c) 2013 Jean Niklas L'orange. All rights reserved.
 *
 * The use and distribution terms for this software are covered by the
 * Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
 * which can be found in the file LICENSE at the root of this distribution.
 *
 * By using this software in any fashion, you are agreeing to be bound by
 * the terms of this license.
 *
 * You must not remove this notice, or any other, from this software.
 */
//package com.java2s;
import java.io.Console;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class Main {
    public static void main(String[] argv) throws Exception {
        boolean on = true;
        System.out.println(setEcho(on));
    }

    /**
     * A static method which peeks into the {@link java.io.Console} class and
     * manually turns on or off echoing in the given console.
     *
     * @param on whether to set echoing on or off.
     *
     * @exception NoSuchMethodException if Java's own console class have no
     * private method named "echo".
     * @exception NoSuchFieldException if Java's own console class have no
     * private field named "echoOff".
     * @exception InvocationTargetException if Java's own console class have a
     * private method named "echo", but that this method tries to invoke that
     * method erroneously.
     * @exception IllegalAccessException if the access restrictions prohibits
     * this method from modifying and using private methods in Java's own
     * console class.
     */
    public static synchronized boolean setEcho(boolean on)
            throws NoSuchMethodException, IllegalAccessException,
            NoSuchFieldException, InvocationTargetException {
        Class params[] = new Class[1];
        params[0] = Boolean.TYPE;
        Method echo = Console.class.getDeclaredMethod("echo", params);
        echo.setAccessible(true);
        boolean res = (Boolean) echo.invoke(null, on);
        Field echoOff = Console.class.getDeclaredField("echoOff");
        echoOff.setAccessible(true);
        echoOff.set(null, res);
        return res;
    }
}

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