So I am creating a CSV file and everytime an action occurs I would like to write the data to the file. The problem I am having is that it will overwrite the data when entering the second time. How do I add the data to the end of the file?
public boolean save_to_csv(){
//check if directory exists, if not create the folder
File folder = new File(Environment.getExternalStorageDirectory() + "/HKA_CAL");
//Environment.getExternalStorageDirectory() get the location of external storage
boolean success = true;
if(!folder.exists())
{
success = folder.mkdir();
}
if (success)
{
//success is true if folder has successfully been created
//now we can create/check if the file exists
File stored_hka = new File(Environment.getExternalStorageDirectory()+"/HKA_CAL/Stored_values.csv");
boolean file_existed=true;
try{
if(!stored_hka.exists()){
stored_hka.createNewFile();
file_existed=false;
}
FileOutputStream fOut = new FileOutputStream(stored_hka);
OutputStreamWriter myOutWriter = new OutputStreamWriter(fOut);
if(!file_existed){
//if the file did not exist we need to write the titles of the csv
myOutWriter.append("Calibration Tracking\r\n");
myOutWriter.append(",ZERO1,,Zero2,,cal1,,cal2,,CALIBRATION FACTORS\r\n");
myOutWriter.append("Date,Stab,Read,Stab,Read,Stab,Read,Stab,Read,Unit S/N,F Zero,F Offset,F Factor\r\n");
}
myOutWriter.append("Date"
+","+get_step3_stab()+","+get_step3_read()
+","+get_step6_stab()+","+get_step6_read()
+","+get_step8_stab()+","+get_step8_read()
+","+get_step11_stab()+","+get_step11_read()
+","+get_sn_num()+","+get_f_zero()
+","+get_f_offset()+","+get_f_factor()+"\r\n"
);
myOutWriter.close();
fOut.close();
}
catch(Exception e){
return false;
}
return true;
}
else
{
return false;
}
}
Instead of doing
new FileOutputStream(stored_hka);
do
new FileOutputStream(stored_hka, true);
This will open the file stored_hka
in append mode instead of overwriting the contents. See the javadoc for FileOutputStream(String name, boolean append) for more information
When you construct your FileWriter or FileOutputStream there's a constructor argument which allows you to put it in append mode:
new FileOutputStream( "/path/to/file", true )
change
FileOutputStream fOut = new FileOutputStream(stored_hka);
to
FileOutputStream fOut = new FileOutputStream(stored_hka, true);
Use the FileOutputStream constructor that includes a boolean for appending
FileInputStream("valid path of file", true);
It will open a file in append mode. Boolean value is for whether you want to open a file in append mode or not.