BAEL-5744 - excel date format (#13123)

apache-poi-2/src/main/java/com/baeldung/poi/excel/dateformat/ExcelDateFormat.java

@@ -0,0 +1,35 @@
+package com.baeldung.poi.excel.dateformat;
+
+import org.apache.poi.ss.usermodel.CellStyle;
+import org.apache.poi.ss.usermodel.CreationHelper;
+import org.apache.poi.xssf.usermodel.XSSFCell;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+
+public class ExcelDateFormat {
+
+    public final static String CUSTOM_DATE_FORMAT = "m/d/yy h:mm";
+
+    /**
+     * Set default date format to a cell
+     * @param dateCell cell to set date format
+     * @param wb workbook to create date format cell style
+     */
+    public void setDefaultDateFormat(XSSFCell dateCell, XSSFWorkbook wb) {
+        CellStyle cellStyle = wb.createCellStyle();
+        cellStyle.setDataFormat((short) 14);
+        dateCell.setCellStyle(cellStyle);
+    }
+
+    /**
+     * Set custom date format to a cell
+     * @param dateCell cell to set date format
+     * @param wb workbook to create date format cell style
+     */
+    public void setCustomDateFormat(XSSFCell dateCell, XSSFWorkbook wb) {
+        CellStyle cellStyle = wb.createCellStyle();
+        CreationHelper createHelper = wb.getCreationHelper();
+        short format = createHelper.createDataFormat().getFormat(CUSTOM_DATE_FORMAT);
+        cellStyle.setDataFormat(format);
+        dateCell.setCellStyle(cellStyle);
+    }
+}

apache-poi-2/src/test/java/com/baeldung/poi/excel/dateformat/DateFormatUnitTest.java

@@ -0,0 +1,95 @@
+package com.baeldung.poi.excel.dateformat;
+
+import org.apache.poi.ss.usermodel.CellStyle;
+import org.apache.poi.xssf.usermodel.XSSFCell;
+import org.apache.poi.xssf.usermodel.XSSFSheet;
+import org.apache.poi.xssf.usermodel.XSSFWorkbook;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.Date;
+
+import static com.baeldung.poi.excel.dateformat.ExcelDateFormat.CUSTOM_DATE_FORMAT;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class DateFormatUnitTest {
+
+    private ExcelDateFormat excelDateFormat;
+
+    private XSSFWorkbook wb;
+
+    private Date date;
+
+
+    @BeforeEach
+    public void setup() {
+        excelDateFormat = new ExcelDateFormat();
+        wb = new XSSFWorkbook();
+        wb.createSheet();
+        date = new Date();
+    }
+
+    @Test
+    void givenExcelDate_whenSetDefaultDate_thenSuccess() {
+        // given Excel Sheet
+        XSSFSheet sheet = wb.getSheetAt(0);
+        XSSFCell dateCell = sheet.createRow(0).createCell(0);
+
+        // when set default date format
+        excelDateFormat.setDefaultDateFormat(dateCell, wb);
+        dateCell.setCellValue(date);
+
+        // then success
+        assertEquals(date, dateCell.getDateCellValue());
+    }
+
+    @Test
+    void givenExcelDate_whenSetCustomDate_thenSuccess() {
+        // given Excel Sheet
+        XSSFSheet sheet = wb.getSheetAt(0);
+        XSSFCell dateCellCustom = sheet.createRow(0).createCell(0);
+
+        // when set custom date format
+        excelDateFormat.setCustomDateFormat(dateCellCustom, wb);
+        dateCellCustom.setCellValue(date);
+
+        // then success
+        assertEquals(CUSTOM_DATE_FORMAT, dateCellCustom.getCellStyle().getDataFormatString());
+        assertEquals(date, dateCellCustom.getDateCellValue());
+    }
+
+    @Test
+    void givenExcelDefaultDateFormat_whenGetDefaultDateFormat_thenSuccess() {
+        // given Excel cell style with default date format
+        CellStyle cellStyle = wb.createCellStyle();
+
+        // when get default date format
+        cellStyle.setDataFormat((short) 14);
+        // then success
+        assertEquals("m/d/yy", cellStyle.getDataFormatString());
+
+        cellStyle.setDataFormat((short) 15);
+        assertEquals("d-mmm-yy", cellStyle.getDataFormatString());
+
+        cellStyle.setDataFormat((short) 16);
+        assertEquals("d-mmm", cellStyle.getDataFormatString());
+
+        cellStyle.setDataFormat((short) 17);
+        assertEquals("mmm-yy", cellStyle.getDataFormatString());
+
+        cellStyle.setDataFormat((short) 18);
+        assertEquals("h:mm AM/PM", cellStyle.getDataFormatString());
+
+        cellStyle.setDataFormat((short) 19);
+        assertEquals("h:mm:ss AM/PM", cellStyle.getDataFormatString());
+
+        cellStyle.setDataFormat((short) 20);
+        assertEquals("h:mm", cellStyle.getDataFormatString());
+
+        cellStyle.setDataFormat((short) 21);
+        assertEquals("h:mm:ss", cellStyle.getDataFormatString());
+
+        cellStyle.setDataFormat((short) 22);
+        assertEquals("m/d/yy h:mm", cellStyle.getDataFormatString());
+    }
+}