记一次list事故,add不同对象最后显示的却是同一条数据重复了很多遍.

Posted 2021-01-15 onewild

List<MemberMsg> memberList = new LinkedList<MemberMsg>();
MemberMsg memberMsg = new MemberMsg();
try {
BufferedInputStream in = new BufferedInputStream(new FileInputStream(file));
POIFSFileSystem fs = new POIFSFileSystem(in);
HSSFWorkbook wb = new HSSFWorkbook(fs);//xslx
HSSFSheet sheet= wb.getSheetAt(0);
int rowNum = sheet.getLastRowNum() + 1;
for (int i = 1; i < rowNum; i++) { 
HSSFRow row = sheet.getRow(i); 
int cellNum = row.getLastCellNum(); 
for (int j = 0; j < cellNum; j++) { 
HSSFCell cell = row.getCell(j);
String cellValue = null;
if(CellType.NUMERIC==(cell.getCellTypeEnum())){
if(DateUtil.isCellDateFormatted(cell)){
Date d = cell.getDateCellValue();
DateFormat formater = new SimpleDateFormat("yyyy-MM-dd");
cellValue = formater.format(d);
}
}else {
cell.setCellType(CellType.STRING);
cellValue = cell.getStringCellValue();
}
switch (j%6) {
case 0:
memberMsg.setCustId(cellValue);
break;
case 1:
memberMsg.setCustName(cellValue);
break;
case 2:
memberMsg.setCustGender(cellValue);
break;
case 3:
memberMsg.setCustPhone(cellValue);
break;
case 4:
memberMsg.setCustBirthday(cellValue);
break;
case 5:
memberMsg.setCustAddress(cellValue);
break;
}
}
System.out.println(memberMsg);
memberList.add(i-1,memberMsg);
}
System.out.println(memberList);

 

输出的结果始终是最后一天的无线循环...

 

list看着像是添加了所有的Member对象的元素,其实list中添加的只是Member的引用,而在这段代码里引用是唯一的,所以最后的指向都是最后一次set的值.
解决办法:每次循环重新创建Member对象,add不同指向的引用.