merge
Merges a range of cells within this sheet.
Memory Caution: Merged region metadata is stored in memory until the workbook is finished. Excessive merging (e.g., thousands of regions) can lead to OutOfMemoryError, especially with Apache POI. For high-frequency merging, consider using FastExcel or increasing heap size.
Streaming Constraint: Both [firstRow] and [lastRow] must be within the current memory window (not yet flushed to disk).
Parameters
first
zero-based index of the first row
last
zero-based index of the last row
first
zero-based index of the first column
last
zero-based index of the last column