我输入了 CSV。其中一列在单元格中没有值。将数据写入另一个 CSV 时，我想在该空单元格中写入 NULL。 我尝试用 NULL 替换“”，但随后它在所有单元格中打印 NULL。 另外，我想排除在代码的硬编码列中添加 NULL 文本，即 UniqueId、IsDelete、Rootpid。我希望它们是空的。

这是迄今为止我的代码:

public static void main(String[] args) throws FileNotFoundException, IOException 
    { 
 
 
        String sourceFilePath = "C://MyData/Emp_Input.csv"; 
        String newFilePath = "C://MyData/Emp_Output.csv"; 
        File sourceCsvFile = new File(sourceFilePath); 
        File finalCsvFile = new File(newFilePath); 
        final Charset Encoding = Charset.forName("UTF-8");  
        String cvsSplitBy = ","; 
 
 
        String line = ""; 
 
        BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(finalCsvFile), Encoding)); 
 
 
        try (BufferedReader br = new BufferedReader(new FileReader(sourceCsvFile)))  
        { 
            line = br.readLine();  
            String newFileLine = "UniqueID" + cvsSplitBy +line + cvsSplitBy  + "IsDelete" + cvsSplitBy + "Rootpid"; 
            writer.write(newFileLine);    
            writer.newLine(); 
 
 
            while ((line = br.readLine()) != null)   
            {    
            /*  if (line.contains("") ) 
                { 
 
                    line = line.replace("", "NULL"); // missing code to replace empty cell of a csv with text as NULL 
                } */ 
 
 
                else if (line.contains("TRUE") || line.contains("FALSE")) 
                { 
                    line = line.replace("TRUE", "1"); 
                    line = line.replace("FALSE", "0"); 
 
                }  
 
 
                    newFileLine =  cvsSplitBy + line + cvsSplitBy + cvsSplitBy; 
                    writer.write(newFileLine);   
                    writer.newLine(); 
 
 
            } 
 
            writer.close(); 
 
        } 
 
 
    } 

请您参考如下方法:

不可能，csv中的空字符串和空字符串没有区别。