src/com/android/phone/common/mail/utils/Utility.java

/**
 * Copyright (c) 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.android.phone.common.mail.utils;

import java.io.ByteArrayInputStream;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;

/**
 * Simple utility methods used in email functions.
 */
public class Utility {
    public static final Charset ASCII = Charset.forName("US-ASCII");

    public static final String[] EMPTY_STRINGS = new String[0];

    /**
     * Returns a concatenated string containing the output of every Object's
     * toString() method, each separated by the given separator character.
     */
    public static String combine(Object[] parts, char separator) {
        if (parts == null) {
            return null;
        }
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < parts.length; i++) {
            sb.append(parts[i].toString());
            if (i < parts.length - 1) {
                sb.append(separator);
            }
        }
        return sb.toString();
    }

    /** Converts a String to ASCII bytes */
    public static byte[] toAscii(String s) {
        return encode(ASCII, s);
    }

    /** Builds a String from ASCII bytes */
    public static String fromAscii(byte[] b) {
        return decode(ASCII, b);
    }

    private static byte[] encode(Charset charset, String s) {
        if (s == null) {
            return null;
        }
        final ByteBuffer buffer = charset.encode(CharBuffer.wrap(s));
        final byte[] bytes = new byte[buffer.limit()];
        buffer.get(bytes);
        return bytes;
    }

    private static String decode(Charset charset, byte[] b) {
        if (b == null) {
            return null;
        }
        final CharBuffer cb = charset.decode(ByteBuffer.wrap(b));
        return new String(cb.array(), 0, cb.length());
    }

    public static ByteArrayInputStream streamFromAsciiString(String ascii) {
        return new ByteArrayInputStream(toAscii(ascii));
    }
}