Apache Ant Source Code Files are inside the Apache Ant source package file like apache-ant-1.10.10-src.zip. Unzip the source package file and go to the "src/main" sub-directory, you will see source code files.

Here is the list of Java source code files of the Apache Ant 1.10.10 in \Users\fyicenter\apache-ant-1.10.10\src\main:

⏎ org/apache/tools/ant/taskdefs/ExecuteStreamHandler.java

/*
 *  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
 *
 *      https://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.tools.ant.taskdefs;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * Used by <code>Execute</code> to handle input and output stream of
 * subprocesses.
 *
 * @since Ant 1.2
 */
public interface ExecuteStreamHandler {

    /**
     * Install a handler for the input stream of the subprocess.
     *
     * @param os output stream to write to the standard input stream of the
     *           subprocess
     * @throws IOException on error
     */
    void setProcessInputStream(OutputStream os) throws IOException;

    /**
     * Install a handler for the error stream of the subprocess.
     *
     * @param is input stream to read from the error stream from the subprocess
     * @throws IOException on error
     */
    void setProcessErrorStream(InputStream is) throws IOException;

    /**
     * Install a handler for the output stream of the subprocess.
     *
     * @param is input stream to read from the error stream from the subprocess
     * @throws IOException on error
     */
    void setProcessOutputStream(InputStream is) throws IOException;

    /**
     * Start handling of the streams.
     * @throws IOException on error
     */
    void start() throws IOException;

    /**
     * Stop handling of the streams - will not be restarted.
     */
    void stop();
}

⏎ org/apache/tools/ant/taskdefs/ExecuteStreamHandler.java

Or download all of them as a single archive file:

File name: apache-ant-1.10.10-fyi.zip
File size: 2392938 bytes
Release date: 2021-04-17
Download 

⇒ ant-1.8.0.jar - Apache Ant

⇐ Download Apache Ant Source Package

⇑ Apache Ant - Java Build Tool

⇑⇑ Java/JAR Tools