本文介绍了Java将新列附加到csv文件的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我想计算一些列数据并将其作为列写入 csv
文件。然后在计算其他数据列之后,我想将它附加到同一个文件但作为新列。
I want to calculate some column data and write it to csv
file as column. Then after calculating other column of data I want to append it to same file but as new column.
这是我做的:
try {
FileWriter writer = new FileWriter(OUT_FILE_PATH, true);
for (int i=0; i<data.size(); i++) {
writer.append(String.valueOf(data.get(i)));
writer.append(",");
writer.append("\n");
}
writer.flush();
writer.close();
} catch (Exception e) {}
结果 - 它将新列附加到第一列,所以我有一个长列。
Result - It appends the new column below the first column, so I have single long column.
谢谢,
推荐答案
您必须逐行读取文件,然后将新列插入每一行。这是使用BufferedReader和BufferedWriter的解决方案
You will have to read your file (line by line) and then insert the new column to every line. Here's a solution using BufferedReader and BufferedWriter
public void addColumn(String path,String fileName) throws IOException{
BufferedReader br=null;
BufferedWriter bw=null;
final String lineSep=System.getProperty("line.separator");
try {
File file = new File(path, fileName);
File file2 = new File(path, fileName+".1");//so the
//names don't conflict or just use different folders
br = new BufferedReader(new InputStreamReader(new FileInputStream(file))) ;
bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file2)));
String line = null;
int i=0;
for ( line = br.readLine(); line != null; line = br.readLine(),i++)
{
String addedColumn = String.valueOf(data.get(i));
bw.write(line+addedColumn+lineSep);
}
}catch(Exception e){
System.out.println(e);
}finally {
if(br!=null)
br.close();
if(bw!=null)
bw.close();
}
}
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