Add Sheet From Data as Map

src/main/java/io/github/millij/poi/ss/writer/AbstractSpreadsheetWriter.java

@@ -109,6 +109,61 @@ public <T> void addSheet(final Class<T> beanType, final List<T> rowObjects, fina
         }
     }
 
+    @Override
+    public void addSheet(final String inSheetName, final List<String> inHeaders,
+            final List<Map<String, String>> rowsData) {
+        // Sanity check
+        if (Objects.isNull(rowsData)) {
+            throw new IllegalArgumentException("AbstractSpreadsheetWriter :: Rows data map is NULL");
+        }
+        if (Objects.isNull(inHeaders)) {
+            throw new IllegalArgumentException("AbstractSpreadsheetWriter :: Headers list is NULL");
+        }
+
+        try {
+            final Sheet exSheet = workbook.getSheet(inSheetName);
+            if (Objects.nonNull(exSheet)) {
+                String errMsg = String.format("A Sheet with the passed name already exists : %s", inSheetName);
+                throw new IllegalArgumentException(errMsg);
+            }
+
+            // Create sheet
+            final Sheet sheet = Objects.isNull(inSheetName) || inSheetName.isBlank() //
+                    ? workbook.createSheet() //
+                    : workbook.createSheet(inSheetName);
+            LOGGER.debug("Added new Sheet[name] to the workbook : {}", sheet.getSheetName());
+
+            // Header
+            final Row headerRow = sheet.createRow(0);
+            for (int cellNum = 0; cellNum < inHeaders.size(); cellNum++) {
+                final Cell cell = headerRow.createCell(cellNum);
+                cell.setCellValue(inHeaders.get(cellNum));
+            }
+
+            // Data Rows
+            for (int i = 0, rowNum = 1; i < rowsData.size(); i++, rowNum++) {
+                final Row row = sheet.createRow(rowNum);
+                final Map<String, String> rowData = rowsData.get(i);
+
+                // Skip if row is null
+                if (Objects.isNull(rowData)) {
+                    continue;
+                }
+
+                for (int cellNum = 0; cellNum < inHeaders.size(); cellNum++) {
+                    final String key = inHeaders.get(cellNum);
+                    final String value = rowData.get(key);
+
+                    final Cell cell = row.createCell(cellNum);
+                    cell.setCellValue(value);
+                }
+            }
+        } catch (Exception ex) {
+            String errMsg = String.format("Error while preparing sheet with passed row objects : %s", ex.getMessage());
+            LOGGER.error(errMsg, ex);
+        }
+    }
+
 
     // Sheet :: Append to existing
 

src/main/java/io/github/millij/poi/ss/writer/SpreadsheetWriter.java

@@ -2,6 +2,7 @@
 
 import java.io.IOException;
 import java.util.List;
+import java.util.Map;
 
 
 /**
@@ -73,6 +74,20 @@ default <T> void addSheet(Class<T> beanClz, List<T> beans, List<String> headers)
     <T> void addSheet(Class<T> beanClz, List<T> beans, String sheetName, List<String> headers);
 
 
+    /**
+     * This method will attempt to add a new sheet and add the rows of data from the rows data. The
+     * <code>null</code> entry in the rows data list will be skipped and no rows will be added to the
+     * sheet.
+     * 
+     * @param sheetName Name of the Sheet. (set it to <code>null</code> for default name)
+     * @param headers a {@link List} of Header names to write in the file. <code>null</code> or empty
+     *        list will default to all writable properties.
+     * @param rowsData List of Map, representing the sheet data. Each Map represents the row data where
+     *        the map elements stores a value for a header as key.
+     */
+    void addSheet(String sheetName, List<String> headers, List<Map<String, String>> rowsData);
+
+
     /**
      * Writes the current Spreadsheet workbook to a file in the specified path.
      * 

src/test/java/io/github/millij/poi/ss/writer/XlsWriterTest.java

@@ -5,7 +5,9 @@
 import java.text.ParseException;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 import org.junit.After;
 import org.junit.Before;
@@ -115,4 +117,65 @@ public void test_write_xls_multiple_sheets() throws IOException {
         gew.write(filepath_output_file);
     }
 
+    @Test
+    public void test_write_map_as_xls_sheet() throws IOException {
+        final String filepath_output_file = _path_test_output.concat("map_2_sheets.xls");
+
+        // Excel Writer
+        LOGGER.info("test_write_map_as_xls_sheet :: Writing to file - {}", filepath_output_file);
+        SpreadsheetWriter gew = new XlsWriter();
+
+        // Headers
+        final List<String> headers = new ArrayList<>();
+        headers.add("Slno.");
+        headers.add("Name");
+        headers.add("Age");
+        headers.add("Gender");
+        headers.add("Height (mts)");
+        headers.add("Address");
+
+        // Data
+        final List<Map<String, String>> rowsDataMap = new ArrayList<>();
+        final Map<String, String> rowDataMap = new HashMap<>();
+        rowDataMap.put("Slno.", "1");
+        rowDataMap.put("Name", "foo");
+        rowDataMap.put("Age", "1");
+        rowDataMap.put("Gender", "Male");
+        rowDataMap.put("Height (mts)", "1.6");
+        rowDataMap.put("Address", "Chennai, India");
+        rowsDataMap.add(rowDataMap);
+
+        // Add Sheets
+        final String sheetName = "test_sheet";
+        gew.addSheet(sheetName, headers, rowsDataMap);
+
+        // Write
+        gew.write(filepath_output_file);
+    }
+
+    @Test
+    public void test_write_map_as_xlsx_sheet_default_sheetname() throws IOException {
+        final String filepath_output_file = _path_test_output.concat("map_2_sheets_default_sheetname.xlsx");
+
+        // Excel Writer
+        LOGGER.info("test_write_map_as_xlsx_sheet_default_sheetname :: Writing to file - {}", filepath_output_file);
+        SpreadsheetWriter gew = new XlsWriter();
+
+        // Headers
+        final List<String> headers = new ArrayList<>();
+        headers.add("Slno.");
+        headers.add("Name");
+        headers.add("Age");
+        headers.add("Gender");
+        headers.add("Height (mts)");
+        headers.add("Address");
+
+        // Add Sheets
+        final String sheetName = null;
+        gew.addSheet(sheetName, headers, new ArrayList<>());
+
+        // Write
+        gew.write(filepath_output_file);
+    }
+
 }

src/test/java/io/github/millij/poi/ss/writer/XlsxWriterTest.java

@@ -5,7 +5,9 @@
 import java.text.ParseException;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 import org.junit.After;
 import org.junit.Before;
@@ -115,4 +117,65 @@ public void test_write_xlsx_multiple_sheets() throws IOException {
         gew.write(filepath_output_file);
     }
 
+    @Test
+    public void test_write_map_as_xlsx_sheet() throws IOException {
+        final String filepath_output_file = _path_test_output.concat("map_2_sheets.xlsx");
+
+        // Excel Writer
+        LOGGER.info("test_write_map_as_xlsx_sheet :: Writing to file - {}", filepath_output_file);
+        SpreadsheetWriter gew = new XlsWriter();
+
+        // Headers
+        final List<String> headers = new ArrayList<>();
+        headers.add("Slno.");
+        headers.add("Name");
+        headers.add("Age");
+        headers.add("Gender");
+        headers.add("Height (mts)");
+        headers.add("Address");
+
+        // Data
+        final List<Map<String, String>> rowsDataMap = new ArrayList<>();
+        final Map<String, String> rowDataMap = new HashMap<>();
+        rowDataMap.put("Slno.", "1");
+        rowDataMap.put("Name", "foo");
+        rowDataMap.put("Age", "1");
+        rowDataMap.put("Gender", "Male");
+        rowDataMap.put("Height (mts)", "1.6");
+        rowDataMap.put("Address", "Chennai, India");
+        rowsDataMap.add(rowDataMap);
+
+        // Add Sheets
+        final String sheetName = "test_sheet";
+        gew.addSheet(sheetName, headers, rowsDataMap);
+
+        // Write
+        gew.write(filepath_output_file);
+    }
+
+    @Test
+    public void test_write_map_as_xlsx_sheet_default_sheetname() throws IOException {
+        final String filepath_output_file = _path_test_output.concat("map_2_sheets_default_sheetname.xlsx");
+
+        // Excel Writer
+        LOGGER.info("test_write_map_as_xlsx_sheet_default_sheetname :: Writing to file - {}", filepath_output_file);
+        SpreadsheetWriter gew = new XlsWriter();
+
+        // Headers
+        final List<String> headers = new ArrayList<>();
+        headers.add("Slno.");
+        headers.add("Name");
+        headers.add("Age");
+        headers.add("Gender");
+        headers.add("Height (mts)");
+        headers.add("Address");
+
+        // Add Sheets
+        final String sheetName = null;
+        gew.addSheet(sheetName, headers, new ArrayList<>());
+
+        // Write
+        gew.write(filepath_output_file);
+    }
+
 }