can anyone help me about rotation Logging issue

My task is : Archieving log file before logging rotation (define
logfile size ,number)
only can copy file but append file.

or someone told how to append log file by using FileHandler or other
class,

Thanks a lot

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for (int i = 0; i < fileNumber; i++) {
String pathName=dirName + fileNamePrefix +i+"."+fileNameSuff;
String currentLog=dirName + fileNamePrefix + i + "."+ fileNameSuff;
File currentLogFile = new File(pathName);
long alen=currentLogFile.length();

if (currentLogFile.length() >= fileSize) {

UtilFile.copyfile(dirName + fileNamePrefix + i + "."+ fileNameSuff,
dirName + "trace_" +fileNamePrefix+ i + "." + fileNameSuff);
(UtilFile.removeFile(dirName + fileNamePrefix + i + "."+ fileNameSuff))
{;
file = new FileHandler(dirName + fileNamePrefix + "%g."+ fileNameSuff,
fileSize, fileNumber, append);
elLogger.addHandler(file);
elLogger.info("info message");
}
} else {
//UtilFile.writeFileAppend(currDate+objName+elLevel,currentLog);

file = new FileHandler(dirName + fileNamePrefix+ "%g." + fileNameSuff,
fileSize,fileNumber, append);
elLogger.addHandler(file);
elLogger.info("info message");
}
}

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