Java - StringWriter flush() method

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Description

The Java StringWriter flush() method flushes the stream.

Declaration

Following is the declaration for java.io.StringWriter.flush() method.

public void flush()

Parameters

NA

Return Value

This method does not return a value.

Exception

NA

Example - Usage of StringWriter flush() method

The following example shows the usage of StringWriter flush() method.

StringWriterDemo.java

package com.tutorialspoint;

import java.io.StringWriter;

public class StringWriterDemo {
   public static void main(String[] args) {

      // create a new writer
      StringWriter sw = new StringWriter();

      // create a new sequence
      String s = "Hello world";

      // write a string
      sw.write(s);

      // flush the writer
      sw.flush();

      // print result
      System.out.println("" + sw.toString());
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Hello World

Example - Using flush() after writing

The following example shows the usage of StringWriter flush() method.

StringWriterDemo.java

package com.tutorialspoint;

import java.io.StringWriter;

public class StringWriterDemo {
   public static void main(String[] args) {
      try {
         StringWriter sw = new StringWriter();
         sw.write("Buffered ");
         sw.write("content");

         sw.flush();  // Has no effect, but safe to call

         System.out.println("Output: " + sw.toString());
      } catch (Exception e) {
         e.printStackTrace();
      }
   }
}

Output

Let us compile and run the above program, this will produce the following result−

Output: Buffered content

Explanation

• flush() is called after writing.

• It does nothing, but the StringWriter continues to function normally.

Example - Repeated flushing

The following example shows the usage of StringWriter flush() method.

StringWriterDemo.java

package com.tutorialspoint;

import java.io.StringWriter;

public class StringWriterDemo {
   public static void main(String[] args) {
      try {
         StringWriter sw = new StringWriter();
         sw.write("Flush ");
         sw.flush();  // Does nothing
         sw.write("has ");
         sw.flush();  // Still does nothing
         sw.write("no effect.");

         System.out.println("Output: " + sw.toString());
      } catch (Exception e) {
         e.printStackTrace();
      }
   }
}

Output

Let us compile and run the above program, this will produce the following result−

Output: Flush has no effect.

Explanation

• Multiple calls to flush() are made between writes.

• All calls are harmless and do not affect the written content.