[英]How can I delete lines of data in textfile using java? eg. my textfile is data.txt
从读取用户需要删除的行以将其删除
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;
public class Delete {
public static void main(String[] args) throws IOException {
File input = new File("data.txt");
FileReader fr = null;
Scanner ob = new Scanner(System.in);
// declare variable
String DeleteWord, str, newDeleteWord;
System.out.print("Enter word you want to delete: ");
DeleteWord = ob.nextLine();
newDeleteWord = (capitalize(DeleteWord));
try {
fr = new FileReader(input);
BufferedReader br = new BufferedReader(fr);
while ((str = br.readLine()) != null) {
if (str.contains(newDeleteWord)) {
System.out.println(str);
}
Scanner read = new Scanner(System.in);
int selection;
System.out.println("Confirm to delete his/her data?\n 1 for yes\n 2 for no");
selection = read.nextInt();
if (selection == 1)
if (str.contains(newDeleteWord)) {
str = "";
}
}
} finally {
fr.close();
}
}
public static String capitalize(String str1) {
if (str1 == null || str1.isEmpty()) {
return str1;
}
return str1.substring(0, 1).toUpperCase() + str1.substring(1);
}
}
如何使用 java 删除文本文件中的数据行? 例如。 我的文本文件是 data.txt
这是一个可能的解决方案:
File inputFile = new File("myFile.txt"); // File which we will read
File tempFile = new File("myTempFile.txt"); // The temporary file where we will write
BufferedReader reader = new BufferedReader(new FileReader(inputFile));
BufferedWriter writer = new BufferedWriter(new FileWriter(tempFile));
String lineToRemove = yourString; // here is your line to remove
String currentLine;
while((currentLine = reader.readLine()) != null) {
String trimmedLine = currentLine.trim(); // we trim it and remove unecessary spaces
if(trimmedLine.equals(lineToRemove)) continue; // If it is equal to our line to remove then do not write it to our file!
writer.write(currentLine + System.getProperty("line.separator"));
}
writer.close();
reader.close();
inputFile.delete(); // we delete the file that we have so that we have no conflicts
boolean successful = tempFile.renameTo(inputFile);
或者
读取列表中的所有行并过滤此列表。
最快的方法是通过Apache Commons-IO(或者你可以自己实现)
Apache 共同点:
List<String> lines = FileUtils.readLines(file);
List<String> updatedLines = lines.stream().filter(s -> !s.contains(searchString)).collect(Collectors.toList());
FileUtils.writeLines(file, updatedLines, false);
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