Java - ObjectOutputStream writeFloat(float val) method

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Description

The Java ObjectOutputStream writeFloat(float val) method writes a 32 bit float.

• It writes the 32-bit binary representation of the float value to the output stream.

• This is not object serialization - it's raw binary writing.

• It's part of the DataOutput interface, which ObjectOutputStream implements.

Declaration

Following is the declaration for java.io.ObjectOutputStream.writeFloat(float val) method.

public void writeFloat(float val)

Parameters

• val − The float value to be written.

Return Value

This method does not return a value.

Exception

• IOException − If I/O errors occur while writing to the underlying stream.

Example - Usage of ObjectOutputStream writeFloat(float val) method

The following example shows the usage of ObjectOutputStream writeFloat(float val) method.

ObjectOutputStreamDemo.java

package com.tutorialspoint;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

public class ObjectOutputStreamDemo {
   public static void main(String[] args) {
      float f = 1.59875f;
      
      try {
         // create a new file with an ObjectOutputStream
         FileOutputStream out = new FileOutputStream("test.txt");
         ObjectOutputStream oout = new ObjectOutputStream(out);

         // write something in the file
         oout.writeFloat(f);
         oout.writeFloat(49.7634764f);

         // close the stream
         oout.close();

         // create an ObjectInputStream for the file we created before
         ObjectInputStream ois = new ObjectInputStream(new FileInputStream("test.txt"));

         // read and print what we wrote before
         System.out.println("" + ois.readFloat());
         System.out.println("" + ois.readFloat());
      } catch (Exception ex) {
         ex.printStackTrace();
      }
   }
}

Output

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

1.59875
49.763477

Example - Write a single float value and read it back

The following example shows the usage of ObjectOutputStream writeFloat(float val) method. We're writing a temperature value 36.5f using writeFloat() and read it back.

ObjectOutputStreamDemo.java

package com.tutorialspoint;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

public class ObjectOutputStreamDemo {
   public static void main(String[] args) {
      String filename = "float1.bin";

      // Write a float value
      try (ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(filename))) {
         float temp = 36.5f;
         oos.writeFloat(temp);
         System.out.println("Wrote float: " + temp);
      } catch (IOException e) {
         e.printStackTrace();
      }

      // Read the float value
      try (ObjectInputStream ois = new ObjectInputStream(new FileInputStream(filename))) {
         float result = ois.readFloat();
         System.out.println("Read float: " + result);
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

Output

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

Wrote float: 36.5
Read float: 36.5

Example - Write multiple float values (e.g. measurements) in sequence

The following example shows the usage of ObjectOutputStream writeFloat(float val) method. We're writing an array of float values representing sensor readings.

ObjectOutputStreamDemo.java

package com.tutorialspoint;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

public class ObjectOutputStreamDemo {
   public static void main(String[] args) {
      String filename = "float_readings.bin";
      float[] readings = { 1.1f, 2.5f, 3.75f, 4.0f };

      // Write the float values
      try (ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(filename))) {
         for (float f : readings) {
            oos.writeFloat(f);
         }
         System.out.println("Wrote " + readings.length + " float values.");
      } catch (IOException e) {
         e.printStackTrace();
      }

      // Read them back
      try (ObjectInputStream ois = new ObjectInputStream(new FileInputStream(filename))) {
         System.out.println("Reading float values:");
         for (int i = 0; i < readings.length; i++) {
            float f = ois.readFloat();
            System.out.println(" - " + f);
         }
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

Output

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

Wrote 4 float values.
Reading float values:
 - 1.1
 - 2.5
 - 3.75
 - 4.0