Commons IO example source code file (CharSequenceReader.java)

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

Java - Commons IO tags/keywords

array, charsequence, charsequence, charsequencereader, charsequencereader, illegalargumentexception, indexoutofboundsexception, io, number, override, override, reader, serializable, size, string

The Commons IO CharSequenceReader.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.commons.io.input;

import java.io.Reader;
import java.io.Serializable;

/**
 * {@link Reader} implementation that can read from String, StringBuffer,
 * StringBuilder or CharBuffer.
 * <p>
 * <strong>Note: Supports {@link #mark(int)} and {@link #reset()}.
 *
 * @version $Revision: 659817 $ $Date: 2008-05-24 14:23:10 +0100 (Sat, 24 May 2008) $
 * @since Commons IO 1.4
 */
public class CharSequenceReader extends Reader implements Serializable {

    private final CharSequence charSequence;
    private int idx;
    private int mark;

    /**
     * Construct a new instance with the specified character sequence.
     *
     * @param charSequence The character sequence, may be <code>null
     */
    public CharSequenceReader(CharSequence charSequence) {
        this.charSequence = (charSequence != null ? charSequence : "");
    }

    /**
     * Close resets the file back to the start and removes any marked position.
     */
    @Override
    public void close() {
        idx = 0;
        mark = 0;
    }

    /**
     * Mark the current position.
     *
     * @param readAheadLimit ignored
     */
    @Override
    public void mark(int readAheadLimit) {
        mark = idx;
    }

    /**
     * Mark is supported (returns true).
     *
     * @return <code>true
     */
    @Override
    public boolean markSupported() {
        return true;
    }

    /**
     * Read a single character.
     *
     * @return the next character from the character sequence
     * or -1 if the end has been reached.
     */
    @Override
    public int read() {
        if (idx >= charSequence.length()) {
            return -1;
        } else {
            return charSequence.charAt(idx++);
        }
    }

    /**
     * Read the sepcified number of characters into the array.
     *
     * @param array The array to store the characters in
     * @param offset The starting position in the array to store
     * @param length The maximum number of characters to read
     * @return The number of characters read or -1 if there are
     * no more
     */
    @Override
    public int read(char[] array, int offset, int length) {
        if (idx >= charSequence.length()) {
            return -1;
        }
        if (array == null) {
            throw new NullPointerException("Character array is missing");
        }
        if (length < 0 || (offset + length) > array.length) {
            throw new IndexOutOfBoundsException("Array Size=" + array.length +
                    ", offset=" + offset + ", length=" + length);
        }
        int count = 0;
        for (int i = 0; i < length; i++) {
            int c = read();
            if (c == -1) {
                return count;
            }
            array[offset + i] = (char)c;
            count++;
        }
        return count;
    }

    /**
     * Reset the reader to the last marked position (or the beginning if
     * mark has not been called).
     */
    @Override
    public void reset() {
        idx = mark;
    }

    /**
     * Skip the specified number of characters.
     *
     * @param n The number of characters to skip
     * @return The actual number of characters skipped
     */
    @Override
    public long skip(long n) {
        if (n < 0) {
            throw new IllegalArgumentException(
                    "Number of characters to skip is less than zero: " + n);
        }
        if (idx >= charSequence.length()) {
            return -1;
        }
        int dest = (int)Math.min(charSequence.length(), (idx + n));
        int count = dest - idx;
        idx = dest;
        return count;
    }

    /**
     * Return a String representation of the underlying
     * character sequence.
     *
     * @return The contents of the character sequence
     */
    @Override
    public String toString() {
        return charSequence.toString();
    }
}