Export Data to Excel in Java

You can easily export data to Microsoft Excel from various available sources, such as JSON and CSV. As a Java developer, you can use multiple techniques to do the job, e.g., you can export data from Arrays, Lists of objects, or even directly from JSON and CSV to Excel documents programmatically. In this article, we’ll discuss easy and simple techniques to export data to Excel using Java and to create Excel XLSX file in Java.

The following topics are discussed/covered in this article:

Java Export Data to Excel Library

For exporting data to Excel, I will be using Aspose.Cells for Java API. It is a powerful spreadsheet manipulation API that lets you create, edit, or convert Excel files within Java applications. The API enables you to perform Excel automation features programmatically without needing a Microsoft Excel application.

You can download the JAR of the API or just add the following pom.xml configuration in your Maven-based Java application to try the below-mentioned code examples.

<repository>
    <id>AsposeJavaAPI</id>
    <name>Aspose Java API</name>
    <url>https://repository.aspose.com/repo/</url>
</repository>
<dependency>
    <groupId>com.aspose</groupId>
    <artifactId>aspose-cells</artifactId>
    <version>21.8</version>
</dependency>

Generate Excel File in Java

You can create an Excel file in Java by following the steps below:

  1. Create an instance of the Workbook class.
  2. Access the preferred Worksheet within the workbook.
  3. Acquire a pointer to the Cells within the chosen worksheet.
  4. Assign values to various cells using the Cells class.
  5. Write the resulting Excel file as an XLSX spreadsheet using the save() method.

The following code snippet demonstrates how to generate an Excel file in Java:

import com.aspose.cells.Cells;
import com.aspose.cells.License;
import com.aspose.cells.Workbook;
import com.aspose.cells.Worksheet;
public class GenerateExcelFileInJava {
public static void main(String[] args) throws Exception {
// Instantiate Aspose.Cells license to avoid trial version watermark
License license = new License();
license.setLicense("Aspose.Cells.lic");
// Instantiate a new Excel workbook instance
Workbook ExcelWorkbook = new Workbook();
// Get reference to first worksheet in the workbook
Worksheet ExcelWorksheet = ExcelWorkbook.getWorksheets().get(0);
// Get reference to Cells collection in the first worksheet
Cells WorksheetCells = ExcelWorksheet.getCells();
// Insert data into the worksheet using the cells collection
WorksheetCells.get("A1").putValue("Customers Report");
WorksheetCells.get("A2").putValue("C_ID");
WorksheetCells.get("B2").putValue("C_Name");
WorksheetCells.get("A3").putValue("C001");
WorksheetCells.get("B3").putValue("Customer1");
WorksheetCells.get("A4").putValue("C002");
WorksheetCells.get("B4").putValue("Customer2");
WorksheetCells.get("A5").putValue("C003");
WorksheetCells.get("B5").putValue("Customer3");
WorksheetCells.get("A6").putValue("C004");
WorksheetCells.get("B6").putValue("Customer4");
// Save the workbook as XLSX
ExcelWorkbook.save("ExcelFile.xlsx");
}
}

Export Array to Excel in Java

You can easily export data from a one-dimensional array or a two-dimensional array to an Excel document. The array can be of a reference type or a value type. You can export data from an array to Excel by following the simple steps mentioned below:

  1. Create an instance of the Workbook class
  2. Get a worksheet in an instance of the Worksheet class
  3. Create an array containing string values
  4. Call the importArray() method with the array
  5. Save the output file by calling the save() method of the Workbook class

The following code sample shows how to export an array of strings to Excel using Java.

// Initialize a Workbook object
Workbook workbook = new Workbook();
// Obtaining the reference of the worksheet
Worksheet worksheet = workbook.getWorksheets().get(0);
// Creating an array containing names as string values
String[] names = new String[] { "Laurence Chen", "Roman Korchagin", "Kyle Huang" };
// Exporting the array of names to first row and first column vertically
worksheet.getCells().importArray(names, 0, 0, true);
// Saving the Excel file
workbook.save("C:\\Files\\output.xlsx");
Export Array to Excel in Java

Export Array to Excel in Java

The Workbook class of the API is the main class to create an Excel spreadsheet. It provides functionality to open and save native excel files. The save() method of this class is used to save the output file at the specified file path.

The Worksheet class represents a single worksheet and provides functionality to work with cells and rows.

The importArray() method of the Cells class exports an array of strings to a worksheet. It takes the following input parameters:

  • stringArray: The array of String values
  • firstRow: The row number of the first cell to export to
  • firstColumn: The column number of the first cell to export to
  • isVertical: It specifies whether to export data vertically or horizontally

The API also provides the overloaded versions of the importArray() method to export an array of integer or double to a worksheet.

Export Two Dimensional Array to Excel

Similarly, you can export a two-dimensional array to an Excel file. The following code sample shows how to export a two-dimensional array to an Excel file in Java.

// Initialize a Workbook object
Workbook workbook = new Workbook();
// Obtaining the reference of the worksheet
Worksheet worksheet = workbook.getWorksheets().get(0);
// Creating a two-dimensional array of integers
int[][] array2D = {
{ 1, 2 },
{ 3, 4 },
{ 5, 6 },
{ 7, 8 }
};
// Exporting the array of names to first row and first column vertically
worksheet.getCells().importArray(array2D, 0, 0);
// Saving the Excel file
workbook.save("C:\\Files\\output.xlsx");
Export Two Dimensional Array to Excel

Export Two Dimensional Array to Excel

The Cells class provides importArray() method to export a two-dimensional array of integers to a worksheet. The API also provides the overloaded versions of this method to export a two-dimensional array of strings or double into a worksheet.

Export ArrayList to Excel in Java

You can export data from an ArrayList to Excel by following the steps mentioned below:

  1. Create an instance of the Workbook class
  2. Get a worksheet in an instance of the Worksheet class
  3. Create an array list containing string values
  4. Call the importArrayList() method with the array list
  5. Save the output file by calling the save() method of the Workbook class

The following code sample shows how to export an ArrayList to Excel in Java.

// Initialize a Workbook object
Workbook workbook = new Workbook();
// Obtaining the reference of the worksheet
Worksheet worksheet = workbook.getWorksheets().get(0);
// Instantiating an ArrayList object
ArrayList<String> list = new ArrayList<String>();
// Add few names to the list as string values
list.add("Laurence Chen");
list.add("Roman Korchagin");
list.add("Kyle Huang");
list.add("Tommy Wang");
// Exporting the contents of ArrayList vertically at the first row and first column of the worksheet.
worksheet.getCells().importArrayList(list, 0, 0, true);
// Saving the Excel file
workbook.save("C:\\Files\\Output.xlsx");
Export Array List to Excel in Java

Export ArrayList to Excel in Java

The importArrayList() method of the Cells class exports an ArrayList of data to a worksheet. It takes four parameters including the ArrayList of data. The other parameters are the firstRow, firstColumn, and isVertical.

Export Collection of Custom Objects to Excel in Java

You can export data from a collection of custom objects to Excel by following the steps mentioned below:

  1. Create an instance of the Workbook class
  2. Get a worksheet in an instance of the Worksheet class
  3. Create an array list of custom objects
  4. Call the importCustomObjects() method with the array list
  5. Save the output file by calling the save() method of the Workbook class

The following code sample shows how to export a collection of custom objects to Excel in Java.

// Initialize a new Workbook
Workbook book = new Workbook();
// Obtaining the reference of the worksheet
Worksheet sheet = book.getWorksheets().get(0);
// Define an ArrayList of Persons
List<Person> list = new ArrayList<Person>();
list.add(new Person("Mike", 25, "Software Engineer"));
list.add(new Person("Steve", 30, "Doctor"));
list.add(new Person("Billy", 35, "Teacher"));
// We pick only Name and Age columns, not all, to export to the worksheet
sheet.getCells().importCustomObjects((Collection)list,
new String[] { "Name", "Age" }, // propertyNames
true, // isPropertyNameShown
0, // firstRow
0, // firstColumn
list.size(), // Number of objects to be exported
true, // insertRows
null, // dateFormatString
false); // convertStringToNumber
// Save the Excel file
book.save("C:\\Files\\Output.xlsx");
Collection of Custom Objects to Excel in Java

Collection of Custom Objects to Excel in Java

The importCustomObjects() method of the Cells class exports a list of custom objects and takes the following parameters. The API also provides the overloaded version of this method that takes fewer parameters.

  • list: The collection of custom objects
  • propertName: Specify the name for a specific property to export. If it is null, it will export all properties of the object
  • isPropertyNameShown: Indicates whether the property name will be exported to the first row
  • firstRow: The row number of the first cell to export
  • firstColumn: The column number of the first cell to export
  • rowNumber: Number of rows to be exported
  • insertRows: Indicates whether extra rows are added to fit data
  • dataFormatString: Date format string for cells
  • convertStringToNumber: Indicates if this method will try to convert string to a number.

Export Data to Excel with Merged Cells in Java

You can export data from a collection of objects to a worksheet containing merged cells by following the steps mentioned below:

  1. Create an instance of the Workbook class with template file path
  2. Get a worksheet in an instance of the Worksheet class
  3. Create an array list of objects
  4. Create an instance of the ImportTableOptions class
  5. Call the importCustomObjects() method with the array list
  6. Save the output file by calling the save() method of the Workbook class

The following code sample shows how to export a collection of custom objects to an Excel worksheet with merged cells in Java.

// Opening an existing Workbook.
Workbook workbook = new Workbook("C:\\Files\\SampleMergedTemplate.xlsx");
// Obtaining the reference of the worksheet
Worksheet sheet = workbook.getWorksheets().get(0);
// Instantiating an ArrayList object
List<Product> productList = new ArrayList<Product>();
// Creating a collection of Products
for (int i = 0; i < 3; i++)
{
Product product = new Product(i, "Product - " + i);
productList.add(product);
}
// Define Table import options
ImportTableOptions tableOptions = new ImportTableOptions();
// Set CheckMergedCells property to true
tableOptions.setCheckMergedCells(true);
tableOptions.setFieldNameShown(false);
// Export data to excel template (in second row, first column)
sheet.getCells().importCustomObjects((Collection)productList, 1, 0, tableOptions);
// Save the Excel file
workbook.save("C:\\Files\\Output.xlsx", SaveFormat.XLSX);
Export Data to Excel with Merged Cells in Java

Export Data to Excel with Merged Cells in Java

The ImportTableOptions class provides several options for exporting data into cells. The setCheckMergedCells indicates whether checking merged cells. The setFieldNameShown property indicates whether the field name should be exported or not.

Copy Rows and Columns from one Excel file to Another in Java

You can easily copy rows and columns from one Excel file to another file programmatically by following the steps mentioned below:

  1. Create an instance of the Workbook class with the source workbook input file
  2. Create an instance of the Workbook class for the destination workbook
  3. Get source and destination worksheets in separate instances of the Worksheet class
  4. Call the copyRows() method of the destination worksheet with the source worksheet cells
  5. Save the destination workbook output file by calling the save() method of the Workbook class

The following code sample shows how to copy rows and columns from one Excel file to another using Java.

// Open the source excel file.
Workbook srcWorkbook = new Workbook("C:\\Files\\Source_Workbook.xlsx");
// Instantiate the destination excel file.
Workbook destWorkbook = new Workbook();
// Get the first worksheet of the source workbook.
Worksheet srcWorksheet = srcWorkbook.getWorksheets().get(0);
// Get the first worksheet of the destination workbook.
Worksheet desWorksheet = destWorkbook.getWorksheets().get(0);
// Copy all the rows of the first worksheet of source Workbook to
// the first worksheet of destination Workbook.
desWorksheet.getCells().copyRows(srcWorksheet.getCells(), 0, 0, srcWorksheet.getCells().getMaxDisplayRange().getRowCount());
// Save the excel file.
destWorkbook.save("C:\\Files\\Destination_Workbook.xlsx");
Copy Rows and Columns from one Excel file to Another in Java

Copy Rows and Columns from one Excel file to Another in Java

You can copy specific rows from one Excel file to another. The following code sample shows how to copy specific rows from one Excel file to another using Java.

// Open the source excel file.
Workbook srcWorkbook = new Workbook("C:\\Files\\Source_Workbook.xlsx");
// Instantiate the destination excel file.
Workbook destWorkbook = new Workbook();
// Get the first worksheet of the source workbook.
Worksheet srcWorksheet = srcWorkbook.getWorksheets().get(0);
// Get the first worksheet of the destination workbook.
Worksheet desWorksheet = destWorkbook.getWorksheets().get(0);
// Copy the second row of the source Workbook to the first row of destination Workbook.
desWorksheet.getCells().copyRow(srcWorksheet.getCells(), 1, 0);
// Copy the fourth row of the source Workbook to the second row of destination Workbook.
desWorksheet.getCells().copyRow(srcWorksheet.getCells(), 3, 1);
// Save the excel file.
destWorkbook.save("C:\\Files\\Destination_Workbook.xlsx");
Copy Specific Rows and Columns from one Excel file to Another in Java

Copy Specific Rows and Columns from one Excel file to Another in Java

The copyRows() method copies data and formats of whole rows. It takes the source worksheet cells to copy as input parameters along with the source row index, destination row index, and the copied row number. The API also provides the overloaded versions of this method to copy rows with CopyOptions and PasteOptions.

Similarly, You can copy column data from one Microsoft Excel document to another using the copyColumn() or copyColumns() methods.

Export JSON Data to Excel in Java

You can easily export data from a JSON file to Excel by following the steps mentioned below:

  1. Create an instance of the Workbook class
  2. Get a worksheet in an instance of the Worksheet class
  3. Read the JSON file
  4. Create an instance of the CellsFactory class
  5. Initiate style by calling the createStyle() method
  6. Set various style properties such as Horizontal Alignment, Font color, etc.
  7. Create an instance of the JsonLayoutOptions class
  8. Set title style with the style object
  9. Set array as table property to true
  10. Call the JsonUtility.importData() method with the JSON input and JsonLayoutOptions
  11. Save the output file by calling the save() method of the Workbook class

The following code sample shows how to export data from a JSON file to Excel using Java.

// Instantiating a Workbook object
Workbook workbook = new Workbook();
Worksheet worksheet = workbook.getWorksheets().get(0);
// Read JSON file
File file = new File("C:\\Files\\sample.json");
BufferedReader bufferedReader = new BufferedReader(new FileReader(file));
String jsonInput = "";
String tempString;
while ((tempString = bufferedReader.readLine()) != null) {
jsonInput = jsonInput + tempString;
}
bufferedReader.close();
// Set Styles
CellsFactory factory = new CellsFactory();
Style style = factory.createStyle();
style.setHorizontalAlignment(TextAlignmentType.CENTER);
style.getFont().setColor(Color.getCyan());
style.getFont().setBold(true);
// Set JsonLayoutOptions
JsonLayoutOptions options = new JsonLayoutOptions();
options.setTitleStyle(style);
options.setArrayAsTable(true);
// Export JSON Data
JsonUtility.importData(jsonInput, worksheet.getCells(), 0, 0, options);
// Save Excel file
workbook.save("C:\\Files\\Output.xlsx");
{
  "quiz": {
    "sport": {
      "q1": {
        "question": "Which one is correct team name in NBA?",
        "answer": "Huston Rocket"
      }
    },
    "maths": {
      "q1": {
        "question": "5 + 7 = ?",
        "answer": "12"
      },
      "q2": {
        "question": "12 - 8 = ?",
        "answer": "4"
      }
    }
  }
}
Export JSON Data to Excel in Java

Export JSON Data to Excel in Java

The CellsFactory class instantiates classes of the Cells model. The createStyle() method of this class creates a new style object of the Style class. The Style class allows setting the display style of Excel documents, such as font, color, alignment, border, etc.

The JsonLayoutOptions class provides the options of JSON layout type. The setTitleStyle method of this class is used to set the defined style of the title. The setArrayAsTable method allows the processing Array as a table.

The API provides JsonUtility class to process the JSON. The importData() method of this class exports the JSON string and takes the following parameters:

  • json: The JSON string
  • cells: The Cells
  • row: The row index
  • column: The column index
  • option: The options to export JSON string

Get CSV Data in Excel using Java

You can export data from a CSV file to Excel by following the simple steps mentioned below:

  1. Create an instance of the LoadOptions class with LoadFormat
  2. Create an instance of the Workbook class with CSV file path and LoadOptions object
  3. Call the save() method of the Workbook class and save the output file

The following code sample shows how to export data from a CSV file to Excel using Java.

// Initialize LoadOptions with CSV LoadFormat.
LoadOptions loadOptions = new LoadOptions(LoadFormat.CSV);
// Open CSV file as a Workbook object
Workbook workbook = new Workbook("C:\\Files\\Sample.csv", loadOptions);
// Save the file as an Excel Documnt
workbook.save("C:\\Files\\Output.xlsx");
id,language,edition,author,streetAddress,city,state,postalCode
01,Java,third,Herbert Schildt,126,San Jone,CA,394221
02,C++,second,EAAAA,126,San Jone,CA,394221
03,.Net,second,E.Balagurusamy,126,San Jone,CA,394221
Export CSV Data to Excel in Java

Export CSV Data to Excel in Java

The LoadOptions class of the API provides options for loading the file. The LoadFormat class contains constants representing the load file formats.

Get a Free License

You can try the API without evaluation limitations by requesting a free temporary license.

Conclusion

In this article, you have learned how to export data to Excel in Java using multiple ways. We explained how to export data from Arrays, JSON, or CSV files to Excel programmatically. Moreover, you have learned how to copy rows and columns from one Excel file to another file using Java. You can learn more about Aspose.Cells for Java API using the documentation. In case of any ambiguity, please feel free to contact us on the forum.

Further Readings

Frequently Asked Questions

How to export data to an XLSX file in Java? You can easily export data from Arrays, Collection of Objects, JSON, and CSV to an XLSX file using easy-to-integrate Aspose.Cells for Java API in your Java application.

How do I export data from JSON to Excel? Aspose.Cells API provides JsonUtility to export data from a JSON file to Excel in Java. You can find simple steps under the Export JSON Data to Excel in Java section.

How do I export data from CSV to Excel in Java? You can simply load a CSV file and save it as XLSX using Aspose.Cells API. You can find simple steps under the Get CSV Data in Excel using Java section.