Name: tb29552 Date: 09/15/99


/*

The following code

  DateFormat df = DateFormat.getInstance();
  df.format(new Object()); // wrong!

should cause a compile-time error, since the signature of DateFormat.format is
  public final String format(Date)
javap java.text.DateFormat confirms this, as does the javadoc at:
http://java.sun.com/products/jdk/1.3/docs/api/java/text/DateFormat.html#format(java.util.Date)

However, it passes the compiler and generates an exception at run-time,
as follows:

% javac df.java
% java df
java.version = 1.3beta
Operating System Name = SunOS
Operating system architecture = sparc
Operating system version = 5.7

Exception in thread "main" java.lang.IllegalArgumentException: Cannot format given Object as a Date
        at java.text.DateFormat.format(DateFormat.java:277)
        at java.text.Format.format(Format.java:129)
        at df.main(df.java:40)


The following byte codes are produced for the format() method call:
  12 invokevirtual #6 <Method java.lang.String format(java.lang.Object)>

This is not the correct method signature, and no check is inserted
in the code to make sure that a Date object is passed.
*/
//
import java.util.Date;
import java.text.DateFormat;
class df {
    public static void outputMessage() {
        System.out.println("java.version = " +
                           System.getProperty("java.version"));
        System.out.println("Operating System Name = " +
                           System.getProperty("os.name"));
        System.out.println("Operating system architecture = " +
                           System.getProperty("os.arch"));
        System.out.println("Operating system version = " +
                           System.getProperty("os.version") +
                           System.getProperty("line.separator"));
    }

    public static void main(String[] args) {
        outputMessage();

        DateFormat df = DateFormat.getInstance();
        df.format(new Object());// wrong!
    }
}

(Review ID: 41807)
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