Bug 94367 cannot clear compiler compliance setting at the project level
i200505092010 Cannot disable the Java compiler project-specific preferences for some projects. Steps to reproduce: 1 - check out from CVS a Java project that has project-specific Java compiler settings enabled (example: org.eclipse.core.runtime). 2 - open the properties dialog for the project, select the Java compiler node, disable project-specific Java compiler preferences. 3 - Commit the changes by pressing "Ok" and reopen the properties dialog. It looks like the settings were not saved (project-specific settings are still enabled).
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/OptionsConfigurationBlock.java
}
	
	/* (non-javadoc)
	 * Update fields and validate.
	 * @param changedKey Key that changed, or null, if all changed.
	 */	
	protected abstract void validateSettings(Key changedKey, String oldValue, String newValue);
	
	
	protected String[] getTokens(String text, String separator) {
		StringTokenizer tok= new StringTokenizer(text, separator); 
		int nTokens= tok.countTokens();
		String[] res= new String[nTokens];
		for (int i= 0; i < res.length; i++) {
			res[i]= tok.nextToken().trim();
		}
		return res;
	}
	
	private static class PropertyChange {
		public final Key key;
		public final String oldValue;
		public final String newValue;
		public PropertyChange(Key key, String oldValue, String newValue) {
			this.key= key;
			this.oldValue= oldValue;
			this.newValue= newValue;
		}
	}