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Commons IO example source code file (ByteArrayOutputStreamTestCase.java)

This example Commons IO source code file (ByteArrayOutputStreamTestCase.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

ascii, ascii, bytearrayoutputstream, bytearrayoutputstream, bytearrayoutputstreamtestcase, data, data, illegalargumentexception, io, requesting, resulting, sizes, string, string, testcase

The Commons IO ByteArrayOutputStreamTestCase.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,
 * See the License for the specific language governing permissions and
 * limitations under the License.
package org.apache.commons.io.output;

import java.io.ByteArrayInputStream;

import junit.framework.TestCase;

 * Basic unit tests for the alternative ByteArrayOutputStream implementation.
 * @author <a href="mailto:jeremias@apache.org">Jeremias Maerki
public class ByteArrayOutputStreamTestCase extends TestCase {

    private static final byte[] DATA;
    static {
        DATA = new byte[64];
        for (byte i = 0; i < 64; i++) {
            DATA[i] = i;

    public ByteArrayOutputStreamTestCase(String name) {

    private int writeData(ByteArrayOutputStream baout, 
                java.io.ByteArrayOutputStream ref,
                int count) {
        if (count > DATA.length) {
            throw new IllegalArgumentException("Requesting too many bytes");
        if (count == 0) {
            return 1;
        } else {
            baout.write(DATA, 0, count);
            ref.write(DATA, 0, count);
            return count;
    private int writeData(ByteArrayOutputStream baout, 
                java.io.ByteArrayOutputStream ref, 
                int[] instructions) {
        int written = 0;
        for (int i = 0; i < instructions.length; i++) {
            written += writeData(baout, ref, instructions[i]);
        return written;

    private static boolean byteCmp(byte[] src, byte[] cmp) {
        for (int i = 0; i < cmp.length; i++) {
            if (src[i] != cmp[i]) {
                return false;
        return true;

    private void checkByteArrays(byte[] expected, byte[] actual) {
        if (expected.length != actual.length) {
            fail("Resulting byte arrays are not equally long");
        if (!byteCmp(expected, actual)) {
            fail("Resulting byte arrays are not equal");

    private void checkStreams(
            ByteArrayOutputStream actual,
            java.io.ByteArrayOutputStream expected) {
        assertEquals("Sizes are not equal", expected.size(), actual.size());
        byte[] buf = actual.toByteArray();
        byte[] refbuf = expected.toByteArray();
        checkByteArrays(buf, refbuf);
    public void testStream() throws Exception {
        int written;
        //The ByteArrayOutputStream is initialized with 32 bytes to match
        //the original more closely for this test.
        ByteArrayOutputStream baout = new ByteArrayOutputStream(32);
        java.io.ByteArrayOutputStream ref = new java.io.ByteArrayOutputStream();
        //First three writes
        written = writeData(baout, ref, new int[] {4, 10, 22});
        assertEquals(36, written);
        checkStreams(baout, ref);

        //Another two writes to see if there are any bad effects after toByteArray()
        written = writeData(baout, ref, new int[] {20, 12});
        assertEquals(32, written);
        checkStreams(baout, ref);

        //Now reset the streams        
        //Test again to see if reset() had any bad effects
        written = writeData(baout, ref, new int[] {5, 47, 33, 60, 1, 0, 8});
        assertEquals(155, written);
        checkStreams(baout, ref);

        //Test the readFrom(InputStream) method
        written = baout.write(new ByteArrayInputStream(ref.toByteArray()));
        assertEquals(155, written);
        checkStreams(baout, ref);

        //Write the commons Byte[]OutputStream to a java.io.Byte[]OutputStream 
        //and vice-versa to test the writeTo() method.
        ByteArrayOutputStream baout1 = new ByteArrayOutputStream(32);
        java.io.ByteArrayOutputStream ref1 = new java.io.ByteArrayOutputStream();
        checkStreams(baout1, ref1);
        //Testing toString(String)
        String baoutString = baout.toString("ASCII");
        String refString = ref.toString("ASCII");
        assertEquals("ASCII decoded String must be equal", refString, baoutString);
        //Make sure that empty ByteArrayOutputStreams really don't create garbage
        //on toByteArray()
        assertSame(new ByteArrayOutputStream().toByteArray(),
            new ByteArrayOutputStream().toByteArray());

Other Commons IO examples (source code examples)

Here is a short list of links related to this Commons IO ByteArrayOutputStreamTestCase.java source code file:

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