Okey, we all know the normal way to throw a IllegalArgumentException in Java:

throw new IllegalArgumentException(); // 37 characters

But there must be a shorter (as in less characters) ways to do so. How can we produce a java.lang.IllegalArgumentException with even less code?

  • The code fragment has to compile and run in java 7.
  • No imports/external packages (e.g. not using java.util.Arrays.toString() )
    • only exception: java.lang because it is automatically imported.
  • You can add own methods/classes.
  • It must throw a java.lang.IllegalArgumentException
    • Edit: the error output (stacktrace) must name it java.lang.IllegalArgumentException, so no subclasses of it.

To have a base to start from:

class Titled {
    public static void main(String[] args) {
        throw new IllegalArgumentException();

8 Answers 8


These were all found by grepping the source code in the package java.lang.

All of them result in a "pure" IllegalArgumentException (i.e. not a subclass of it).

The ones marked * only work if you add " throws Exception" (18 characters) to your main declaration, as they throw a checked exception of some kind.

12 (30?) characters*


This will result in:

java.lang.IllegalArgumentException: timeout value is negative

22 (40?) characters*

new Thread().join(-1);

22 characters


30 characters

  • \$\begingroup\$ No, it will not compile because it can throw a InterruptedException. \$\endgroup\$ Commented Sep 6, 2014 at 21:11
  • 1
    \$\begingroup\$ The compiler will error: unreported exception InterruptedException; must be caught or declared to be thrown \$\endgroup\$ Commented Sep 6, 2014 at 21:12
  • 1
    \$\begingroup\$ Whoops, Ideone automatically adds throws Exception to the main method. I've added a note in my post. \$\endgroup\$
    – Doorknob
    Commented Sep 6, 2014 at 21:17
  • 1
    \$\begingroup\$ Mwhahaha! I managed to find my IllegalArgumentException by memory. No need for tools like grep. Except the changed rules make it invalid. :-( \$\endgroup\$
    – Justin
    Commented Sep 6, 2014 at 22:31
  • 1
    \$\begingroup\$ @usr No; primitives aren't objects in Java. \$\endgroup\$
    – Doorknob
    Commented Sep 7, 2014 at 20:37

Here's a nice short way to do it, in 17 13 chars:

new Long("");

It throws a NumberFormatException, which is an IllegalArgumentException. This and this verify it.

Equivalently, one could do

new Byte("");
  • \$\begingroup\$ Sorry, clearified what I am looking for: I am looking a for 'clean' IllegalArgumentException. It should name it so. \$\endgroup\$ Commented Sep 6, 2014 at 19:35
  • \$\begingroup\$ @luckydonald what do you mean by "naming"? The type given in the stacktrace? If so, would an exception-with-cause be acceptable if the IllegalArgumentException was passed internally as the cause to another exception? \$\endgroup\$
    – nanofarad
    Commented Sep 7, 2014 at 11:52
  • \$\begingroup\$ The purpose is to replace the normal throw new IAE(). The code, when executed in a static (main) method has to fail Exception in thread "main" java.lang.IllegalArgumentException at Untitled.main(Titled.java:4). Were it fails (line, file, stacktrace) doesn't matter. \$\endgroup\$ Commented Sep 7, 2014 at 12:32

22 characters:


Running example
Javadoc: java.lang.Character.toChars(int)

Some nice looking variants:

Character.toChars(~4); // 22 characters, number can be any non-negative (and -0)
Character.toChars(1<<7); // 24 characters

~i is the same as -1 * (i+1) because it inverts the bits. So we will get a illegal parameter, because it is smaller then 0.
1<<7 will create a too high number by shifting the 1 seven times. (same as multiply it 7 times with 2). The last accepted Value seems to be 1114111, 1114112 will fail. Note: this might change depending on your environment, and could be not always reliable.

See the Oracle Docs "Bitwise and Bit Shift Operators" and "Primitive Data Types"

28 characters:

And if you don't like using the character class in a character count competition*:

Enum.valueOf(Enum.class,""); // 28 characters

*) Just to make this pun.

  • \$\begingroup\$ Doesn't need to be any positive; you can do any non-negative (ie ~0 works too) \$\endgroup\$
    – Justin
    Commented Sep 7, 2014 at 14:33
  • \$\begingroup\$ I thought about 0 as a positive because it has no minus. But your right, and even Character.toChars(~-0); works. \$\endgroup\$ Commented Sep 7, 2014 at 16:45
  • 4
    \$\begingroup\$ ~0 is -1. Not sure what ~-0 does for you, besides requiring an additional character. \$\endgroup\$ Commented Sep 7, 2014 at 19:37
  • \$\begingroup\$ It looks funnier xD \$\endgroup\$ Commented Sep 7, 2014 at 20:58

21 characters:


As per the documentation, getProperty and setProperty throw IllegalArgumentException if the key is empty.


25 Characters

Creates a vector with an invalid (negative) length:

new java.util.Vector(-1);


Exception in thread "main" java.lang.IllegalArgumentException: Illegal Capacity: -1
    at java.util.Vector.<init>(Vector.java:129)
    at java.util.Vector.<init>(Vector.java:144)
    at Titled.main(Titled.java:3)

Here's 24 characters:


This will throw an IllegalFormatException, which is an IllegalArgumentException.


19 characters:


Throws java.util.UnknownFormatConversionException, which inherits from IllegalFormatException, which, in turn, inherits from IllegalArgumentException;


14 Characters


17 Characters


As far as code that directly throws IllegalArgumentException, these will do it.

From documentation: 
Thread.sleep(int millis): 
Throws:IllegalArgumentException - if the value of millis is negative
InterruptedException - if any thread has interrupted the current thread. 

so direct code is 17 chars, if you're being a super stickler and counting the chars to add a throws clause for the interupted exception you can shorten it by just throwing the raw Exception class

  • 1
    \$\begingroup\$ this.wait(-1) does not work in the main function, due to main being static. \$\endgroup\$ Commented Jul 14, 2015 at 2:08
  • \$\begingroup\$ Thread.sleep(-1) requires you to add a throws declaration to the function, so it gets longer again. error: unreported exception InterruptedException; must be caught or declared to be thrown \$\endgroup\$ Commented Jul 14, 2015 at 2:13

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