Bug 26547 Automatic closing of strings is not smart enough
Trying to add strings around an existing identifier is highly annoying when the Automatically close Strings option is set. For example, when I try to add Strings around: System.out.println(a) before a then I get two quotes. I suggest the rule to not close a string when there is a letter that belongs to an identifier to the left or right.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/CompilationUnitEditor.java
private boolean fCloseBrackets= true;
		private boolean fCloseStrings= true;
		
		private int fOffset;
		private int fLength;
		public void setCloseBracketsEnabled(boolean enabled) {
			fCloseBrackets= enabled;
		}
		public void setCloseStringsEnabled(boolean enabled) {
			fCloseStrings= enabled;
		}
		
		private boolean isResfOfLineEmpty(IDocument document, int offset) {
			if (offset == document.getLength())
				return true;
				
			try {
				IRegion line= document.getLineInformationOfOffset(offset);
				String string= document.get(offset, line.getOffset() + line.getLength() - offset);
				for (int i= 0; i < string.length(); i++)
					if (!Character.isWhitespace(string.charAt(i)))
						return false;
				return true;
				
			} catch (BadLocationException e) {
				return true;
			}
		}