src/examples/src/org/apache/poi/examples/xssf/streaming/DeferredGeneration.java

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   this work for additional information regarding copyright ownership.
   The ASF licenses this file to You under the Apache License, Version 2.0
   (the "License"); you may not use this file except in compliance with
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       http://www.apache.org/licenses/LICENSE-2.0

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   distributed under the License is distributed on an "AS IS" BASIS,
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   See the License for the specific language governing permissions and
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package org.apache.poi.examples.xssf.streaming;

import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.xssf.streaming.DeferredSXSSFSheet;
import org.apache.poi.xssf.streaming.DeferredSXSSFWorkbook;

import java.io.FileOutputStream;
import java.io.IOException;

/**
 * This sample demonstrates how to use DeferredSXSSFWorkbook to generate workbooks in a streaming way.
 * This approach avoids the use of temporary files and can be used to output to streams like
 * HTTP response streams.
 */
public class DeferredGeneration {

    public static void main(String[] args) throws IOException {
        try (DeferredSXSSFWorkbook wb = new DeferredSXSSFWorkbook()) {
            DeferredSXSSFSheet sheet1 = wb.createSheet("new sheet");

            sheet1.setRowGenerator((ssxSheet) -> {
                for (int i = 0; i < 10; i++) {
                    Row row = ssxSheet.createRow(i);
                    Cell cell = row.createCell(1);
                    cell.setCellValue("value " + i);
                }
            });

            try (FileOutputStream fileOut = new FileOutputStream("DeferredGeneration.xlsx")) {
                wb.write(fileOut);
            } finally {
                wb.dispose();
            }
        }
    }
}