what does method erasure mean?

[ravisha andar]

Hi All,

I just read in an article that for a method to compile the method signatures and method erasures should be different.

What exactly does method erasure mean?

Thanks

[Stephan van Hulst]

The erasure is the method signature that you're left with after generic parameters have been erased.

Let's say you have the following two methods:

public <T> T doNothing(T arg) {
  return arg;
}

public Object doNothing(Object arg) {
  return arg;
}

This is not allowed, because the generic parameter T gets replaced by Object during erasure, leaving the method with the exact same signature as the second method. This however *is* allowed:

public <T extends String> T doNothing(T arg) {
  return arg;
}

The generic parameter gets replaced by String, so this method successfully overloads the one with the Object parameter.