Error-handling / Self-Validating mechanism
isValid Method
If you have a validator, I would expect a method to check if it is valid.
If you add an isValid method, you would get rid of the errorInfo == null check, which isn't a good idea. It exposes how the validator works internally, and relies on this never changing.
errorMessage Type
Why is your error message a String? You are creating a new StringBuffer and calling toString every time an error is appended. Just make errorMessage a StringBuffer or StringBuilder and call toString when the error message is retrieved (which should be done via a getter, not direct access).
Naming
setErrorMessage: What this actually does is appendErrorMessage
Spacing
I know it's knit-picking, but please follow the general conventions regarding spacing. Before and after ?, :, and + should be a space.
General Idea
I'm not too sure what this is good for (maybe I'm missing something?). It doesn't seem like the SelfValidator class can be reused for any other data. The three fields and their types are hardcoded, as is the validation mechanism (no empty string and no null allowed). Couldn't all your code be replaced with something like this:
  private boolean isValid = true;

  public MyClass(String object1, String object2, int value1) {
    super();
    if (object1 == null || object2 == null || object1.equals(&quot;&quot;) || object2.equals(&quot;&quot;)) {
        this.isValid = false;
    }
  }

  public isValid() {
    return isValid;
  }

It seems just as flexible as your approach, but is easier to read.