CharArrayBuffer implements CharSequence, Serializable { public void ensureCapacity(final int required) { if (required <= 0) { return; } final int available = this.array.length - this.len; if (required > available) { expand(this.len + required); } } CharArrayBuffer(final int capacity); void append(final char[] b, final int off, final int len); void append(final String str); void append(final CharArrayBuffer b, final int off, final int len); void append(final CharArrayBuffer b); void append(final char ch); void append(final byte[] b, final int off, final int len); void append(final ByteArrayBuffer b, final int off, final int len); void append(final Object obj); void clear(); char[] toCharArray(); @Override char charAt(final int i); char[] array(); int capacity(); @Override int length(); void ensureCapacity(final int required); void setLength(final int len); boolean isEmpty(); boolean isFull(); int indexOf(final int ch, final int from, final int to); int indexOf(final int ch); String substring(final int beginIndex, final int endIndex); String substringTrimmed(final int beginIndex, final int endIndex); @Override CharSequence subSequence(final int beginIndex, final int endIndex); @Override String toString();  }
@Test public void testEnsureCapacity() throws Exception { final CharArrayBuffer buffer = new CharArrayBuffer(4); buffer.ensureCapacity(2); Assert.assertEquals(4, buffer.capacity()); buffer.ensureCapacity(8); Assert.assertEquals(8, buffer.capacity()); }