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Saving & Loading

Kexcel serializes a workbook to .xlsx bytes in memory with encode(). Writing those bytes to a file is platform-specific — the library stays free of platform I/O so it can run everywhere.

Encoding to bytes

val bytes: ByteArray? = excel.encode()

encode() returns the complete .xlsx file as a ByteArray (or null if encoding fails). These bytes are a valid workbook you can save, upload, or hand to a share sheet.

Writing to a file

import java.io.File

val bytes = excel.encode() ?: error("Failed to encode workbook")
File("out.xlsx").writeBytes(bytes)

val bytes = excel.encode() ?: error("Failed to encode workbook")

// App-private storage:
context.openFileOutput("out.xlsx", Context.MODE_PRIVATE).use { it.write(bytes) }

// ...or a user-chosen location via the Storage Access Framework:
context.contentResolver.openOutputStream(uri)?.use { it.write(bytes) }

// Hand `bytes` to your Kotlin/Native or Swift file-writing code, e.g. via
// NSData, or use a multiplatform file picker such as FileKit.
val bytes = excel.encode() ?: error("Failed to encode workbook")

Multiplatform file I/O

For picking and writing files across targets, a library like FileKit pairs well with Kexcel — the sample app uses it.

Loading

Load a workbook from bytes or a stream:

val fromBytes = Excel.decodeBytes(bytes)
val fromStream = Excel.decodeStream(inputStream)

A full round-trip

Because encode() produces valid .xlsx bytes, encoding and decoding round-trips cleanly:

val excel = Excel.createExcel()
excel["Sheet1"].appendRow(listOf(TextCellValue("persisted"), IntCellValue(7)))

val bytes = excel.encode()!!             // encode in memory
val reloaded = Excel.decodeBytes(bytes)  // decode the same bytes

val a1 = reloaded["Sheet1"].cell(CellIndex.indexByString("A1")).value // persisted
val b1 = reloaded["Sheet1"].cell(CellIndex.indexByString("B1")).value // 7

Notes

  • encode() reflects the current in-memory model — call it after all your edits.
  • Only the .xlsx (Office Open XML) format is supported. Legacy .xls files cannot be read or written.
  • Encoding does no filesystem access, so it is safe to call on any thread and any platform.