The write() method that is defined in java.io.OutputStream, takes an integer argument intended to be between 0 and 255. Since an int is otherwise designed to store 4 byte numbers, failure to validate user input may lead to unexpected results.
The general contract for write is that one byte is written to the output stream. The byte to be written is the eight low-order bits of the argument b. The 24 high-order bits of b are ignored. Java Specification
Non-Compliant Code Example
The non-compliant coding example shown below takes in a value from the user without validating it. If this value is > 255, it will result in a wrap around. For instance, write(305) will print '1' since the lower order bits of 305 are preserved while the top 24 order bits are lost. That is, the result is remainder modulo 256 of the absolute value of the input.
class console_write {
public static void main(String args[])
{
//Any input value > 255 will result in unexpected output
System.out.write(args[1]);
}
}
Compliant Solution
References
Java I/O, Elliotte Rusty Harold