使用Java搜索和打印文本文件

Question

如何搜索文本并从.txt文件中打印出特定的文本行？ 例如，我有一个名为airlines.txt的txt文件，我搜索MMHHHAAAA。 然后，我想从“ MMHHHAAAA：Malaysian Airlines”行中提取“ Malaysian Airlines”

//Scan file airlines.txt
Scanner scanner = new Scanner(new File("airlines.txt"));
while(scanner.hasNextLine()){
//Will this work?
  String s = scan.nextLine();
  Scanner line = new Scanner(s);
  String airline;
//How do i continue from here to scan for MMHHHAAAA and then print out the following line of text
}
System.out.println("Airline is" + airline);
return airline;
}

Answer 1

您可以在Java 8中使用它：

final Path path = Paths.get("airlines.txt");

final Optional<String> theLine;

try (
    final Stream<String> lines = Files.lines(path, StandardCharsets.UTF_8)
) {
    theLine = lines.filter(s -> s.startsWith("MMHHHAAAA:"))
        .findFirst();
}

if (theLine.isPresent())
    // do something with theLine.get()

Answer 2

您可以使用String.indexOf("")方法。

if (s.indexOf("your-search-string") != -1) {
   //matched the pattern
   System.out.println(s);
}

您可以使用substring()后提取部分: 。 System.out.println(s.substring(":"));

阅读有关Java字符串及其方法的更多信息。

Answer 3

一种可能性

    Scanner scanner = new Scanner(new File("airlines.txt"));
    while(scanner.hasNextLine()){

      String currentLine = scanner.nextLine();
      if(currentLine.indexOf("MMHHHAAAA") != -1){
          String airline = currentLine.split(":")[1];
          System.out.println("Airline is " + airline);
      }
    }