Writing data to an excel sheet through java

You can do it using Apache POI .

Apache POI is a powerful Java library to work with different Microsoft Office file formats such as Excel, Power point, Visio, MS Word etc. The name POI was originally an acronym for Poor Obfuscation Implementation, referring humorously to the fact that the file formats seemed to be deliberately obfuscated, but poorly, since they were successfully reverse-engineered.

create new excel file

import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
//..
HSSFWorkbook workbook = new HSSFWorkbook();
HSSFSheet sheet = workbook.createSheet("Sample sheet");
//Create a new row in current sheet
Row row = sheet.createRow(0);
//Create a new cell in current row
Cell cell = row.createCell(0);
//Set value to new value
cell.setCellValue("Blahblah");

and than write the data in that excel file

HSSFWorkbook workbook = new HSSFWorkbook();
HSSFSheet sheet = workbook.createSheet("Sample sheet");

Map<String, Object[]> data = new HashMap<String, Object[]>();
data.put("1", new Object[] {"Emp No.", "Name", "Salary"});
data.put("2", new Object[] {1d, "John", 1500000d});
data.put("3", new Object[] {2d, "Sam", 800000d});
data.put("4", new Object[] {3d, "Dean", 700000d});

Set<String> keyset = data.keySet();
int rownum = 0;
for (String key : keyset) {
    Row row = sheet.createRow(rownum++);
    Object [] objArr = data.get(key);
    int cellnum = 0;
    for (Object obj : objArr) {
        Cell cell = row.createCell(cellnum++);
        if(obj instanceof Date) 
            cell.setCellValue((Date)obj);
        else if(obj instanceof Boolean)
            cell.setCellValue((Boolean)obj);
        else if(obj instanceof String)
            cell.setCellValue((String)obj);
        else if(obj instanceof Double)
            cell.setCellValue((Double)obj);
    }
}

try {
    FileOutputStream out = 
            new FileOutputStream(new File("C:\\new.xls"));
    workbook.write(out);
    out.close();
    System.out.println("Excel written successfully..");

} catch (FileNotFoundException e) {
    e.printStackTrace();
} catch (IOException e) {
    e.printStackTrace();
}