public class EvaluationCache {
    
    //...........
    
    public PlainValueCellCacheEntry getPlainValueEntry(int bookIndex, int sheetIndex,
                                                       int rowIndex, int columnIndex, ValueEval value) {

        Loc loc = new Loc(bookIndex, sheetIndex, rowIndex, columnIndex);
        PlainValueCellCacheEntry result = _plainCellCache.get(loc);
        if (result == null) {
            result = new PlainValueCellCacheEntry(value);
            _plainCellCache.put(loc, result);
            if (_evaluationListener != null) {
                _evaluationListener.onReadPlainValue(sheetIndex, rowIndex, columnIndex, result);
            }
        } else {
            // TODO - if we are confident that this sanity check is not required, we can remove 'value' from plain value cache entry
            if (!areValuesEqual(result.getValue(), value)) {
                throw new IllegalStateException("value changed"); //在这里报错！
            }
            if (_evaluationListener != null) {
                _evaluationListener.onCacheHit(sheetIndex, rowIndex, columnIndex, value);
            }
        }
        return result;
    }
    
    //................
    
}