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Android example source code file (CharSequences.java)

This example Android source code file (CharSequences.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" TM.

Java - Android tags/keywords

charsequence, charsequences, indexoutofboundsexception, string

The CharSequences.java Android example source code

/*
 * Copyright (C) 2007 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.internal.util;

/**
 * {@link CharSequence} utility methods.
 */
public class CharSequences {

    /**
     * Adapts {@link CharSequence} to an array of ASCII (7-bits per character)
     * bytes.
     * 
     * @param bytes ASCII bytes
     */
    public static CharSequence forAsciiBytes(final byte[] bytes) {
        return new CharSequence() {
            public char charAt(int index) {
                return (char) bytes[index];
            }

            public int length() {
                return bytes.length;
            }

            public CharSequence subSequence(int start, int end) {
                return forAsciiBytes(bytes, start, end);
            }

            public String toString() {
                return new String(bytes);
            }
        };
    }

    /**
     * Adapts {@link CharSequence} to an array of ASCII (7-bits per character)
     * bytes.
     *
     * @param bytes ASCII bytes
     * @param start index, inclusive
     * @param end index, exclusive
     *
     * @throws IndexOutOfBoundsException if start or end are negative, if end
     *  is greater than length(), or if start is greater than end
     */
    public static CharSequence forAsciiBytes(final byte[] bytes,
            final int start, final int end) {
        validate(start, end, bytes.length);
        return new CharSequence() {
            public char charAt(int index) {
                return (char) bytes[index + start];
            }

            public int length() {
                return end - start;
            }

            public CharSequence subSequence(int newStart, int newEnd) {
                newStart -= start;
                newEnd -= start;
                validate(newStart, newEnd, length());
                return forAsciiBytes(bytes, newStart, newEnd);
            }

            public String toString() {
                return new String(bytes, start, length());
            }
        };
    }

    static void validate(int start, int end, int length) {
        if (start < 0) throw new IndexOutOfBoundsException();
        if (end < 0) throw new IndexOutOfBoundsException();
        if (end > length) throw new IndexOutOfBoundsException();
        if (start > end) throw new IndexOutOfBoundsException();
    }

    /**
     * Compares two character sequences for equality.
     */
    public static boolean equals(CharSequence a, CharSequence b) {
        if (a.length() != b.length()) {
            return false;
        }

        int length = a.length();
        for (int i = 0; i < length; i++) {
            if (a.charAt(i) != b.charAt(i)) {
                return false;
            }
        }
        return true;
    }
    
    /**
     * Compares two character sequences with API like {@link Comparable#compareTo}.
     * 
     * @param me The CharSequence that receives the compareTo call.
     * @param another The other CharSequence.
     * @return See {@link Comparable#compareTo}.
     */
    public static int compareToIgnoreCase(CharSequence me, CharSequence another) {
        // Code adapted from String#compareTo
        int myLen = me.length(), anotherLen = another.length();
        int myPos = 0, anotherPos = 0, result;
        int end = (myLen < anotherLen) ? myLen : anotherLen;

        while (myPos < end) {
            if ((result = Character.toLowerCase(me.charAt(myPos++))
                    - Character.toLowerCase(another.charAt(anotherPos++))) != 0) {
                return result;
            }
        }
        return myLen - anotherLen;
    }
}

Other Android examples (source code examples)

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