【实践】Closeable【 Closeable-close()，Flushable-flush()，Runnable-run()，Serializable无方法！,Callable-call()】

package java.io;

import java.io.IOException;

A {@code Closeable} is a source or destination of data that can be closed.
The close method is invoked to release resources that the object is
holding (such as open files).

public interface Closeable extends AutoCloseable {

/**
 * Closes this stream and releases any system resources associated
 * with it. If the stream is already closed then invoking this
 * method has no effect.
 *
 * <p> As noted in {@link AutoCloseable#close()}, cases where the
 * close may fail require careful attention. It is strongly advised
 * to relinquish the underlying resources and to internally
 * <em>mark</em> the {@code Closeable} as closed, prior to throwing
 * the {@code IOException}.
 *
 * @throws IOException if an I/O error occurs
 */
public void close() throws IOException;

}