java - Collections.copy(dest, src) 仍然引用源集合

Question

我在论坛中搜索了处理集合深度复制的方法，但在我手中，Collections.copy(dest, src) 无法按预期工作。我错过了什么吗？

List<Column> mergedStudies = new ArrayList<Column>(Arrays.asList(new Column[studyColumns.size()]));
    Collections.copy(mergedStudies, studyColumns);

    for (Iterator itrStudyRecColumns = mergedStudies.iterator(); itrStudyRecColumns.hasNext();) {
        Column studyRecCol = (Column) itrStudyRecColumns.next();
        for (Iterator itrStudyValColumns = studyValueColumns.iterator(); itrStudyValColumns.hasNext();) {
            Column studyValCol = (Column) itrStudyValColumns.next();
            if (studyRecCol.getColumnName().equals(studyValCol.getColumnName())) {
                // Note: this method dereferences copies to an existing destination collection WITH items appended to end of collection.
                CellValue[] cellValArray = studyValCol.getCellValues().toArray(new CellValue[studyValCol.getCellValues().size()]);
                studyRecCol.getCellValues().addAll(new ArrayList<CellValue>(Arrays.asList(cellValArray)));
                break;
            }
        }
    }

谢谢

克里斯

Answer 1

Collections.copy()不(也不声称)执行深层复制:

Copies all of the elements from one list into another. After the operation, the index of each copied element in the destination list will be identical to its index in the source list. The destination list must be at least as long as the source list. If it is longer, the remaining elements in the destination list are unaffected.

它只是进行浅复制(导致每个列表中复制引用到同一组对象)。