alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (AppendableCharSequence.java)

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

Learn more about this Java project at its project page.

Java - Java tags/keywords

appendablecharsequence, illegalargumentexception, illegalstateexception, indexoutofboundsexception, override, string, util

The AppendableCharSequence.java Java example source code

/*
 * Copyright 2013 The Netty Project
 *
 * The Netty Project 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 io.netty.util.internal;


import java.util.Arrays;

public final class AppendableCharSequence implements CharSequence, Appendable {
    private char[] chars;
    private int pos;

    public AppendableCharSequence(int length) {
        if (length < 1) {
            throw new IllegalArgumentException("length: " + length + " (length: >= 1)");
        }
        chars = new char[length];
    }

    private AppendableCharSequence(char[] chars) {
        if (chars.length < 1) {
            throw new IllegalArgumentException("length: " + chars.length + " (length: >= 1)");
        }
        this.chars = chars;
        pos = chars.length;
    }

    @Override
    public int length() {
        return pos;
    }

    @Override
    public char charAt(int index) {
        if (index > pos) {
            throw new IndexOutOfBoundsException();
        }
        return chars[index];
    }

    /**
     * Access a value in this {@link CharSequence}.
     * This method is considered unsafe as index values are assumed to be legitimate.
     * Only underlying array bounds checking is done.
     * @param index The index to access the underlying array at.
     * @return The value at {@code index}.
     */
    public char charAtUnsafe(int index) {
        return chars[index];
    }

    @Override
    public AppendableCharSequence subSequence(int start, int end) {
        return new AppendableCharSequence(Arrays.copyOfRange(chars, start, end));
    }

    @Override
    public AppendableCharSequence append(char c) {
        try {
            chars[pos++] = c;
        } catch (IndexOutOfBoundsException e) {
            expand();
            chars[pos - 1] = c;
        }
        return this;
    }

    @Override
    public AppendableCharSequence append(CharSequence csq) {
        return append(csq, 0, csq.length());
    }

    @Override
    public AppendableCharSequence append(CharSequence csq, int start, int end) {
        if (csq.length() < end) {
            throw new IndexOutOfBoundsException();
        }
        int length = end - start;
        if (length > chars.length - pos) {
            chars = expand(chars, pos + length, pos);
        }
        if (csq instanceof AppendableCharSequence) {
            // Optimize append operations via array copy
            AppendableCharSequence seq = (AppendableCharSequence) csq;
            char[] src = seq.chars;
            System.arraycopy(src, start, chars, pos, length);
            pos += length;
            return this;
        }
        for (int i = start; i < end; i++) {
            chars[pos++] = csq.charAt(i);
        }

        return this;
    }

    /**
     * Reset the {@link AppendableCharSequence}. Be aware this will only reset the current internal position and not
     * shrink the internal char array.
     */
    public void reset() {
        pos = 0;
    }

    @Override
    public String toString() {
        return new String(chars, 0, pos);
    }

    /**
     * Create a new {@link String} from the given start to end.
     */
    public String substring(int start, int end) {
        int length = end - start;
        if (start > pos || length > pos) {
            throw new IndexOutOfBoundsException();
        }
        return new String(chars, start, length);
    }

    /**
     * Create a new {@link String} from the given start to end.
     * This method is considered unsafe as index values are assumed to be legitimate.
     * Only underlying array bounds checking is done.
     */
    public String subStringUnsafe(int start, int end) {
        return new String(chars, start, end - start);
    }

    private void expand() {
        char[] old = chars;
        // double it
        int len = old.length << 1;
        if (len < 0) {
            throw new IllegalStateException();
        }
        chars = new char[len];
        System.arraycopy(old, 0, chars, 0, old.length);
    }

    private static char[] expand(char[] array, int neededSpace, int size) {
        int newCapacity = array.length;
        do {
            // double capacity until it is big enough
            newCapacity <<= 1;

            if (newCapacity < 0) {
                throw new IllegalStateException();
            }

        } while (neededSpace > newCapacity);

        char[] newArray = new char[newCapacity];
        System.arraycopy(array, 0, newArray, 0, size);

        return newArray;
    }
}

Other Java examples (source code examples)

Here is a short list of links related to this Java AppendableCharSequence.java source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.