import java.io.*;

public class Test_input {
public static void main(String[] args)
{
// TODO Auto-generated method stub
System.out.println("Please type something");
byte[] b = new byte[200];
try
{
System.in.read(b);
}
catch(Exception e) { System.out.println("there is an error");}
String str = new String(b);
System.out.println("You Typed\t"+ str);
}

}

In the above code the byte is set to 200, but below the byte limit is set to 20, and string is immutable. So it is your choice and decision when to limit the byte size using an inputstream class.

import java.io.*;
public class Test_Input2 {
public static void main(String[] args)
{
// TODO Auto-generated method stub
System.out.println("Please type something");
byte[] b = new byte[20];
try
{
System.in.read(b);
}
catch(Exception e) { System.out.println("there is an error");}
String str = new String(b);
System.out.println("You Typed\t"+ str + " total byte " + (byte)str.length());
}
}

If you exceed the byte limit, inputstream will ignore the rest

java.io
Class InputStream

java.lang.Object
  java.io.InputStream

All Implemented Interfaces:

Closeable

Direct Known Subclasses:

AudioInputStream, ByteArrayInputStream, FileInputStream, FilterInputStream, InputStream, ObjectInputStream, PipedInputStream, SequenceInputStream, StringBufferInputStream

public abstract class InputStream
extends Object
implements Closeable

This abstract class is the superclass of all classes representing an input stream of bytes.

Applications that need to define a subclass of InputStream must always provide a method that returns the next byte of input.

Since:

JDK1.0

See Also:

BufferedInputStream, ByteArrayInputStream, DataInputStream, FilterInputStream, read(), OutputStream, PushbackInputStream

---

Constructor Summary
InputStream()

 

Method Summary
int	available()           Returns the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream.
void	close()           Closes this input stream and releases any system resources associated with the stream.
void	mark(int readlimit)           Marks the current position in this input stream.
boolean	markSupported()           Tests if this input stream supports the mark and reset methods.
abstract  int	read()           Reads the next byte of data from the input stream.
int	read(byte[] b)           Reads some number of bytes from the input stream and stores them into the buffer array b.
int	read(byte[] b, int off, int len)           Reads up to len bytes of data from the input stream into an array of bytes.
void	reset()           Repositions this stream to the position at the time the mark method was last called on this input stream.
long	skip(long n)           Skips over and discards n bytes of data from this input stream.