Bug 56965 Classpath variable name has to be a valid Java identifier
I20040330 window>preferences>java>classpath variables>new type '444' an error is displayed in the dialog : Invalid name: ''444' is not a valid Java identifier.'. I don't see any reason why the name of the variable has to be a valid Java identifier.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/VariableCreationDialog.java
} else if (nameConflict(name)) {
			status.setError(NewWizardMessages.getString("VariableCreationDialog.error.nameexists")); 
		}
		return status;
	}
	
	private boolean nameConflict(String name) {
		if (fElement != null && fElement.getName().equals(name)) {
			return false;
		}
		for (int i= 0; i < fExistingNames.size(); i++) {
			CPVariableElement elem= (CPVariableElement)fExistingNames.get(i);
			if (name.equals(elem.getName())){
				return true;
			}
		}
		return false;
	}
	
	
	private StatusInfo pathUpdated() {
		StatusInfo status= new StatusInfo();
		
		String path= fPathField.getText();
		if (path.length() > 0) { 
			if (!Path.ROOT.isValidPath(path)) {
				status.setError(NewWizardMessages.getString("VariableCreationDialog.error.invalidpath")); 
			} else if (!new File(path).exists()) {
				status.setWarning(NewWizardMessages.getString("VariableCreationDialog.warning.pathnotexists")); 
			}