Java implementation to manipulate excel spreadsheets

Recently, the teacher assigned a task to simply add, delete, change and check excel files with the suffix XLSX in Java. Although it is a simple procedure, but as a new contact for me or some bumps and turns. But the good news is that we've done it.

  First, I imported a poi.jar. There are many resources available for download on the web

XSSFSheet sheet = null;
XSSFWorkbook book = null;

A: check   (find the excel sheet in the specified location locally and output it in the console)

public void print_excel(){

　　//Gets the number of rows in an excel spreadsheet
　　int lastrownumber = sheet.getLastRowNum();
　　String ret=" ";
　　//To get the data
　　for(a=0;a<lastrownumber;a++){
　　　　XSSFRow row=sheet.getRow(a);
　　　　//Gets the number of columns in an excel spreadsheet
　　　　int lastcellnum=row.getLastCellNum();
　　　　for(b=0;b<lastcellnum;b++){

　　　　　　XSSFCell cell =row.getCell(b);

　　　　　　//Determines the type returned by the cell and assigns the value to ret
　　　　　　ret=excel_operation.getExcelCellValue(cell);
　　　　　　System.out.print(ret+" ");
　　　　}
　　System.out.println();
　　} 
}

Change 2: (modify the contents of a cell in the excel spreadsheet)

public void set_excelcell(int i,int j,String str){
　　//Get row information
　　XSSFRow row=sheet.getRow(i-1);
　　//Gets the column information
　　XSSFCell cell =row.getCell(j-1);
　　//Gets the contents of the cell being modified
　　String string = excel_operation.getExcelCellValue(cell);
　　//Change the contents of the cell to STR
　　cell.setCellValue(str);
　　System.out.println(" Has been to "+string+" Instead of "+str);
}

Three: increasing (insert a line in the excel spreadsheet to the specified location)

public void insert(int rowIndex, String[] objs) { 
　　if(rowIndex == 0) { 
　　　　throw new IllegalArgumentException(" You can't cut in 0 Ok, the first 0 Rows are defined! "); 
　　} 
　　if(rowIndex > sheet.getLastRowNum() + 1) { 
　　　　throw new IllegalArgumentException(" At most, it can only be inserted after the last row. "); 
　　} 
　　int referRowIndex = -1; //Refer to the line number.
　　if(sheet.getPhysicalNumberOfRows() <= 1) { 

　　　　referRowIndex = rowIndex - 1; 
　　} else { 
　　　　referRowIndex = rowIndex - 1; 
　　if(rowIndex == sheet.getLastRowNum() + 1) { //Insert the last row
　　　　//Don't do anything
　　} else { 

　　　　//I'm going to move down a little bit
　　　　sheet.shiftRows(rowIndex, sheet.getLastRowNum(), 1, true, false); 
　　　　} 
　　} 
　　Row targetRow = sheet.createRow(rowIndex); 
　　Row referRow = sheet.getRow(referRowIndex); //The reference line
　　Cell targetCell, referCell; 

　　for (int i = 0; i < objs.length; i++) { 
　　targetCell = targetRow.createCell(i); 
　　referCell = referRow.getCell(i); 

　　targetCell.setCellStyle(referCell.getCellStyle()); 
　　targetCell.setCellType(referCell.getCellType()); 

　　targetCell.setCellValue(objs[i]);//Set the value
　　} 
}

Four: delete (deletes the contents of the specified row)

//Delete a row (in Excel, rows count from 0)
　　public void delete(int rowIndex) {

　　//The last line was deleted
　　if(rowIndex == sheet.getLastRowNum()) { 
　　　　sheet.removeRow(sheet.getRow(sheet.getLastRowNum()));

　　//Not the last line
　　} else { 
　　　　sheet.shiftRows(rowIndex + 1, sheet.getLastRowNum(), -1, true, false); 
　　　　sheet.removeRow(sheet.getRow(sheet.getLastRowNum() + 1)); 
　　} 
}

Five: determining the return type   (because the contents of excel sheet are different, there are characters, integers, etc., the type must be determined to output)

private static String getExcelCellValue(XSSFCell cell) {
　　String ret=" ";
　　try {
　　　　//Returns a space when the type of the return value is null
　　　　if (cell == null) {
　　　　　　ret = " "; 
　　　　//When the return value is of type string
　　　　} else if (cell.getCellType() == XSSFCell.CELL_TYPE_STRING) {
　　　　　　ret = cell.getStringCellValue();

　　　　//When the return value is of type numeric
　　　　} else if (cell.getCellType() == XSSFCell.CELL_TYPE_NUMERIC) {
　　　　　　ret = "" + cell.getNumericCellValue();

　　　　//When the type of the return value is the expression type
　　　　} else if (cell.getCellType() == XSSFCell.CELL_TYPE_FORMULA) {
　　　　　　ret = cell.getCellFormula();

　　　　//When the type of the return value is an exception type
　　　　} else if (cell.getCellType() == XSSFCell.CELL_TYPE_ERROR) {
　　　　　　ret = " " + cell.getErrorCellValue();

　　　　//When the return value is of type Boolean
　　　　　} else if (cell.getCellType() == XSSFCell.CELL_TYPE_BOOLEAN) {
　　　　　　ret = " " + cell.getBooleanCellValue();

　　　　//When the type of the return value is null
　　　　} else if (cell.getCellType() == XSSFCell.CELL_TYPE_BLANK) {
　　　　ret = " ";
　　　　}
　　} catch (Exception ex) {
　　　　ex.printStackTrace();
　　ret = " ";
　　}
　　return ret;
}