ObjectOutputStream useProtocolVersion(int) in Java

useProtocolVersion(int): This method is available in the java.io.ObjectOutputStream class of Java.

Syntax:

void java.io.ObjectOutputStream.useProtocolVersion(int version) throws IOException

This method takes one argument. This method specifies the stream protocol version to use when writing the stream.

This routine provides a hook to enable the current version of serialization to write in a format that is backward compatible with a previous version of the stream format.

Parameters: One parameter is required for this method.

version: use ProtocolVersion from java.io.ObjectStreamConstants.

Throws:

1. IllegalStateException - if called after any objects have been serialized.

2. IllegalArgumentException - if the invalid version is passed in.

3. IOException - if I/O errors occur

Approach 1: When no exception

Java

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamConstants;

public class ObjectOutputStreamuseProtocolVersion {
    public static void main(String[] args) throws IOException {

        FileOutputStream fileStream = new FileOutputStream("D:\\hello.txt");

        ObjectOutputStream objStream = new ObjectOutputStream(fileStream);

        int version = ObjectStreamConstants.PROTOCOL_VERSION_1;
        objStream.useProtocolVersion(version);
        System.out.println("Protocol version");

        objStream.close();
    }
}

Output:

Protocol version

Approach 2: IllegalArgumentException

Java

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

public class ObjectOutputStreamuseProtocolVersion {
    public static void main(String[] args) throws IOException {

        FileOutputStream fileStream = new FileOutputStream("D:\\hello.txt");

        ObjectOutputStream objStream = new ObjectOutputStream(fileStream);

        int version = 0;
        objStream.useProtocolVersion(version);
        System.out.println("Protocol version");

        objStream.close();
    }
}

Output:

Exception in thread "main" java.lang.IllegalArgumentException: unknown version: 0
	at java.base/java.io.ObjectOutputStream.useProtocolVersion(ObjectOutputStream.java:321)
	at com.ObjectOutputStream.ObjectOutputStreamuseProtocolVersion.main(ObjectOutputStreamuseProtocolVersion.java:15)

Some more methods of ObjectOutputStream

close(): This method must be called to release any resources associated with the stream.

defaultWriteObject(): This method writes the non-static and non-transient fields of the current class to this stream.

flush(): This method flushes the stream.

putFields(): This method retrieves the object used to buffer persistent fields to be written to the stream.

reset(): The state is reset to be the same as a new ObjectOutputStream.

write(byte[]): This method writes an array of bytes. 

write(int): This method writes a byte.

write(byte[], int, int): This method writes a sub array of bytes.

writeBoolean(boolean): This method writes a boolean.

writeByte(int): This method writes an 8-bit byte.

writeBytes(String): This method writes a String as a sequence of bytes.

writeChar(int): This method writes a 16-bit char.

writeChars(String): This method writes a String as a sequence of chars.

writeDouble(double): This method writes a 64-bit double.

writeFields(): This method writes the buffered fields to the stream.

writeFloat(float): This method writes a 32-bit float.

writeInt(int): This method writes a 32-bit int.

writeLong(long): This method writes a 64-bit long.

writeObject(Object): This method writes the specified object to the ObjectOutputStream.

writeShort(int): This method writes a 16-bit short.

writeUnshared(Object): This method writes an "unshared" object to the ObjectOutputStream.

writeUTF(String): This method is primitive data are written of this String in modified UTF-8 format.