Introduction
The Java.io ObjectInputStream is one of the significant class in java.io packages. The main feature of this object input stream is to read the objects instead of reading bytes, because of this the performance is little better than other readers. The Java.io ObjectInputStream reads only the objects which are serialized in java. The class should implements the serializable while reading object from that class. The object input stream class is subclass to input stream class and wrap input stream into the object input stream for to read objects.
Conceptual
figure
Declaration
Java.io ObjectInputStream class is declared below:
Public class ObjectInputStream extends InputStream implements ObjectInput, ObjectStreamConstants Table
| Constructor | Description |
|---|---|
| Protected ObjectInputStream() | The function of this constructor is to create the object input stream instance for reimplemetation. |
| ObjectInputStream(InputStream in) | The function of this constructor is to create the object input stream instance and used to read from input stream. |
Table
| Method | Description |
|---|---|
| int read () | By using this method it reads the bytes of data from the input stream. |
| void read fully( byte[] buf) | The function of this method is to read the bytes from the input stream and store in array buffer. |
| int skipBytes(int n) | From the input stream this method skips over and throw out ‘n’ bytes of data. |
| int read(byte[] buf, int off, int n) | By using this method it reads the data up to 'n' bytes from the input stream to an array of the bytes. |
| String readUTF() | The function of this method is to read the content in the string format and have encoded by UTF-8 format. |
| Object readObject() | The function of this method is to read the object from input stream |
Description
From the following classes, methods are inherited to object input stream class.
- Java.io.Object
- Java.io.InputStream
- Java.io.ObjectInput
Examples
Usage of Object readObject() method.
[c]import java.io.*;
public class ObjectInputStream
{
public static void main(String[] args)
{
String s = "Hello World";
byte[] b = {'S', 'P', 'L', 'E', 'S', 'S', 'O', 'N', 'S'};
try {
// creating a new file with an ObjectOutputStream
FileOutputStream out = new FileOutputStream"test.txt");
ObjectOutputStream oout = new ObjectOutputStream(out);
// To write something in the file
oout.writeObject(s);
oout.writeObject(b);
oout.flush();
// creating an ObjectInputStream for the file we created before
ObjectInputStream ois =
new ObjectInputStream(new FileInputStream("test.txt"));
// Read and print an object and to cast it as string
System.out.println("" + (String) ois.readObject());
// Read and print an object and cast it as string
byte[] read = (byte[]) ois.readObject();
String s2 = new String(read);
System.out.println("" + s2);
} catch (Exception ex) {
ex.printStackTrace();
}
}
}[/c]
Output
The result will be as follows.
[c]Hello World
SPLESSONS[/c]
Usage of String readUTF() method.
[c]import java.io.*;
public class ObjectInputStream
{
public static void main(String[] args)
{
String s = "Hello World!";
try {
// creating a new file with an ObjectOutputStream
FileOutputStream out = new FileOutputStream("test.txt");
ObjectOutputStream oout = new ObjectOutputStream(out);
// write something in the file
oout.writeUTF(s);
oout.writeUTF("SP LESSONS");
oout.flush();
// creating an ObjectInputStream for the file we created before
ObjectInputStream ois =
new ObjectInputStream(new FileInputStream("test.txt"));
// for to read and print the string
System.out.println("" + ois.readUTF());
// for to read and print the string
System.out.println("" + ois.readUTF());
} catch (Exception ex) {
ex.printStackTrace();
}
}
}[/c]
Output
The result will be as follows.
[c]Hello World!
SP LESSONS[/c]