Is there an beautiful way to assert pre-conditions in Java methods?

Question

A lot of my functions have a whole load of validation code just below the declarations:

if ( ! (start < end) ) {
    throw new IllegalStateException( \"S         


        

Answer 1

Check out the Cofoja project which provides contracts for Java through annotations. It provides Pre-/Postconditions and Invariants. Also in contrast to other Java implementations it correctly handles contracts defined in parent classes/interfaces. Contract evaluation can be enabled/disabled at runtime.

Here is a code snippet from their tutorial:

import com.google.java.contract.Invariant;
import com.google.java.contract.Requires;

@Invariant("size() >= 0")
interface Stack {
  public int size();

  @Requires("size() >= 1")
  public T pop();

  public void push(T obj);
}