如何使用Java替换文件中的特定行? [英] How to replace a specific line in a file using Java?
本文介绍了如何使用Java替换文件中的特定行?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
如何使用FileWriter和PrintWriter在文本文件中的特定行上书写?我不想每次都制作一个新文件.
How do I write over a specific line in a text file using FileWriter and PrintWriter? I don't want to have to make a new file every time.
我可以循环浏览文件,在指定的行号处获取String的长度,然后在到达该行时使用该长度退格(删除String),然后写入新的数据?
Can I just cycle through the file, get the length of the String at the indicated line number, and then use that length to backspace once I get to that line (to delete the String), and write in the new data?
public static void setVariable(int lineNumber, String data) {
try {
// Creates FileWriter. Append is on.
FileWriter fw = new FileWriter("data.txt", true);
PrintWriter pw = new PrintWriter(fw);
//cycles through file until line designated to be rewritten is reached
for (int i = 1; i <= lineNumber; i++) {
//TODO: need to figure out how to change the append to false to overwrite data
if (i == lineNumber) {
pw.println(data);
pw.close();
} else {
// moves printwriter focus to next line (doesn't overwrite)
pw.println("");
}
}
}
}
推荐答案
如果您使用的是Java 7或更高版本,并且lineNumber
从1开始,则可以执行以下操作:
If you are using Java 7 or higher and if lineNumber
starts in 1, you can do the following:
public static void setVariable(int lineNumber, String data) throws IOException {
Path path = Paths.get("data.txt");
List<String> lines = Files.readAllLines(path, StandardCharsets.UTF_8);
lines.set(lineNumber - 1, data);
Files.write(path, lines, StandardCharsets.UTF_8);
}
很明显,如果lineNumber
从0开始,则:
Obviously if lineNumber
starts in 0, then:
lines.set(lineNumber, data);
这篇关于如何使用Java替换文件中的特定行?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文