Combine multiple excel file to one excel with multiple sheets

I have multiple excel files and each excel file contains one sheet. I need to combine all excel file into one file with multiple sheets using java

Eg: Excel1.xlsx,Excel2.xlsx,etc
Each file contains one sheetname AAA.
I need to have Merge.xlsx with Sheet1,Sheet2,Sheet3,etc
Sheet1 from Excel1.xlsx,Sheet2 from Excel2.xlsx,etc

I need all formatting as it is while combine