Java - ObjectOutputStream writeBoolean(boolean val) method

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Description

The Java ObjectOutputStream writeBoolean(boolean val) method writes a boolean.

• Writes a single boolean value to the output stream.

• true is written as byte 1, false as byte 0.

• This method is inherited from DataOutput, implemented by ObjectOutputStream.

This is not object serialization. It writes raw binary data.

Declaration

Following is the declaration for java.io.ObjectOutputStream.writeBoolean(boolean val) method.

public void writeBoolean(boolean val)

Parameters

• val − The boolean 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 writeBoolean(boolean val) method

The following example shows the usage of ObjectOutputStream writeBoolean(boolean 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) {
      boolean b = true;
      
      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.writeBoolean(b);
         oout.writeBoolean(false);

         // 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.readBoolean());
         System.out.println("" + ois.readBoolean());
      } catch (Exception ex) {
         ex.printStackTrace();
      }
   }
}

Output

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

true
false

Example - Write a single boolean value and read it back

The following example shows the usage of ObjectOutputStream writeBoolean(boolean val) method. We're writing true to a file and verify it by reading 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 = "bool1.bin";

      // Write a boolean value
      try (ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(filename))) {
         oos.writeBoolean(true);  // writes byte 1
         System.out.println("Wrote boolean: true");
      } catch (IOException e) {
         e.printStackTrace();
      }

      // Read it back
      try (ObjectInputStream ois = new ObjectInputStream(new FileInputStream(filename))) {
         boolean value = ois.readBoolean();
         System.out.println("Read boolean: " + value);
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

Output

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

Wrote boolean: true
Read boolean: true

Example - Write a list of booleans to a file and read them back

The following example shows the usage of ObjectOutputStream writeBoolean(boolean val) method. We're writing multiple boolean values using writeBoolean() method.

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 = "bool_list.bin";
      boolean[] flags = {true, false, true, true, false};

      // Write the list of booleans
      try (ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(filename))) {
         for (boolean b : flags) {
            oos.writeBoolean(b);
         }
         System.out.println("Boolean array written.");
      } catch (IOException e) {
         e.printStackTrace();
      }

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

Output

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

Boolean array written.
Reading booleans:
 - true
 - false
 - true
 - true
 - false