我不确定为什么下面的代码会导致 Java 每次都覆盖文件中已有的数据,而我想要它做的实际上是将每条新数据写入新行。我已经包含了相关的代码片段(我知道您可能认为变量中有错误,但实际上没有,程序运行正常)。有人可以帮助我了解导致此问题的原因吗?是我使用文件编写器的方式吗?
String DirToWriteFile = System.getProperty("user.dir") + "/VirtualATM.txt"; //Get path to write text file to.
String Details = "Name: " + name + " CardNo: " + CardNo + " Current Balance: " + balance + " overdraft? " + OverDraft + " OverDraftLimit: " + OverDraftLimit + " pin: " + PinToWrite;
try{
//Create writer to write to files.
File file = new File(DirToWriteFile);
Writer bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), "UTF8"));
// FileReader reads text files in the default encoding.
FileReader fileReader = new FileReader("VirtualATM.txt");
// Always wrap FileReader in BufferedReader.
BufferedReader bufferedReader = new BufferedReader(fileReader);
String CurrentData = "";
while((bufferedReader.readLine()) != null) {
line = CurrentData;
bw.write(CurrentData);
((BufferedWriter) bw).newLine();
}
bw.write(Details);
System.out.println("Account created!");
System.out.println(name + " Your card number is: " + CardNo);
// close the reader.
bufferedReader.close();
//Close the writer.
bw.close();
最佳答案
使用另一个 FileOutputStream 构造函数,该构造函数采用 boolean 值 append 参数作为第二个参数。传入 true
,因为这将告诉 Java 将文本附加到现有文件而不是覆盖它。
即更改此:
File file = new File(DirToWriteFile);
Writer bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), "UTF8"));
对此:
File file = new File(DirToWriteFile);
FileOutputStream fos = new FileOutputStream(file, true); // **note second param?**
Writer bw = new BufferedWriter(new OutputStreamWriter(fos, "UTF8"));
关于java - 为什么这段代码会导致 Java 覆盖文件中的数据?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/26088586/