我正在使用此代码在 Excel 工作表末尾添加行。每次调用函数时。初始化时的 last=0 。
connectionTime, mobility, angleofArrival, sender and peer
是一些变量，其值随着函数调用而改变。当调用函数时，我想在每一行中保存值。
public void excelWriter(DTNHost sender, DTNHost peer){
String fileName = "Results.xls";
try {
File file = new File(fileName);
FileInputStream fin = null;
HSSFWorkbook workbook = null;
HSSFSheet worksheet = null;
FileOutputStream fout = null;
POIFSFileSystem lPOIfs = null;
if (file.exists()) {
try{
fout = new FileOutputStream(fileName, true);
fin = new FileInputStream(fileName);
lPOIfs = new POIFSFileSystem(fin);
workbook = new HSSFWorkbook(lPOIfs);
worksheet = workbook.getSheet("POI Worksheet");
for (int i=0; i<workbook.getNumberOfSheets(); i++) {
System.out.println( workbook.getSheetName(i) );
}
HSSFSheet sheet = workbook.getSheetAt(0);
last = sheet.getLastRowNum();
}catch (IOException e) {
e.printStackTrace();
}catch (NullPointerException e){
e.printStackTrace();
}
} else {
//create new file
try{
fout = new FileOutputStream(file);
}catch (IOException e) {
e.printStackTrace();
}
workbook = new HSSFWorkbook();
worksheet = workbook.createSheet("POI Worksheet");
}
if(last != 0){
last = worksheet.getLastRowNum();
}else{
last = worksheet.getLastRowNum()+1;
System.out.println(last);
}
HSSFRow row = worksheet.createRow(last++);
HSSFCell cellA1 = row.createCell((int)0);
cellA1.setCellValue(sender+" and "+peer);
HSSFCell cellB1 = row.createCell((int) 1);
cellB1.setCellValue(mobility);
HSSFCell cellC1 = row.createCell((int) 2);
cellC1.setCellValue(angleOfArival);
HSSFCell cellD1 = row.createCell((int) 3);
cellD1.setCellValue(connectionTime);
System.out.println("Data written");
workbook.write(fout);
fout.flush();
fout.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
////End
}
但它只添加一行(仅第一次)。我已经对其进行了调试。每次调用函数时 last 值都会增加，但不会每次都添加行。谁能告诉我我在这里做错了什么。
最佳答案
public void excelWriter(DTNHost sender, DTNHost peer) {
String fileName = "Results.xls";
int last = 0;
try {
File file = new File(fileName);
FileInputStream fin = null;
HSSFWorkbook workbook = null;
HSSFSheet worksheet = null;
FileOutputStream fout = null;
POIFSFileSystem lPOIfs = null;
if (file.exists()) {
try {
fin = new FileInputStream(fileName);
lPOIfs = new POIFSFileSystem(fin);
workbook = new HSSFWorkbook(lPOIfs);
worksheet = workbook.getSheet("POI Worksheet");
last = worksheet.getLastRowNum() + 1;
fout = new FileOutputStream(fileName);
} catch (IOException e) {
e.printStackTrace();
} catch (NullPointerException e) {
e.printStackTrace();
}
} else {
// create new file
try {
fout = new FileOutputStream(file);
} catch (IOException e) {
e.printStackTrace();
}
workbook = new HSSFWorkbook();
worksheet = workbook.createSheet("POI Worksheet");
}
HSSFRow row = worksheet.createRow(last);
HSSFCell cellA1 = row.createCell((int) 0);
cellA1.setCellValue(sender + " and " + peer);
HSSFCell cellB1 = row.createCell((int) 1);
cellB1.setCellValue("mobility");
HSSFCell cellC1 = row.createCell((int) 2);
cellC1.setCellValue("angleOfArival");
HSSFCell cellD1 = row.createCell((int) 3);
cellD1.setCellValue("connectionTime");
System.out.println("Data written");
workbook.write(fout);
fout.flush();
fout.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
//// End
}
上述方法有效，一旦加载工作表，OutputStream就会打开，已删除行HSSFSheet Sheet = workbook.getSheetAt(0);，因为它是多余的，您已经拥有可以从中获取lastRowNum的工作表实例。语句HSSFRow row = worksheet.createRow(last++);使用后增量运算符，因此它将继续写入同一行，“last”变量的值将递增仅在该语句执行后。
关于java - 每次在JAVA中调用函数时在Excel中添加行，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/36007625/