The function of flush method in java

The flush() method in Java can force the buffer data to be written to the underlying output stream and clear the buffer contents. It is used to: 1. Write data immediately; 2. Ensure data integrity before closing the output stream; 3. View the writing status of the underlying stream during debugging.

The role of the flush() method in Java

The flush() method in Java is used to force the buffer to The data in the buffer is written to the underlying output stream and all contents in the buffer are cleared.

Principle

In Java, output streams use buffers to improve efficiency and reduce the number of calls to underlying resources. The buffer temporarily stores the data to be output. When the buffer reaches a certain size or the flush() method is called, the data will be written to the underlying stream.

When to use

Normally, the flush() method does not need to be called manually, the Java virtual machine automatically calls it when appropriate. However, it may be necessary to manually call the flush() method in the following situations:

• Ensure that the data is written immediately: If the data needs to be written to the underlying stream immediately, rather than waiting When the buffer fills up, the flush() method can be called to force writing.
• Before closing the output stream: Calling the flush() method before closing the output stream can ensure that all data in the buffer has been written.
• Debugging: The flush() method can be used for debugging purposes to see whether data is correctly written to the underlying stream.

Usage example

<code class="java">FileOutputStream fileOutputStream = new FileOutputStream("output.txt");
fileOutputStream.write("Hello, world!".getBytes());
fileOutputStream.flush(); // 强制写入缓冲区中的数据
fileOutputStream.close();</code>

Note:

• Calling the flush() method will not turn off the output Stream, it is only used to clear the data in the buffer.
• Theflush() method does not affect data that has been written to the underlying stream.

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