java需要帮助读取日志中以特定单词结尾的特定行

Question

我需要java代码的帮助来读取一个日志文件，该文件可以打印所有以起始字结尾的行

我的文件包含：

test 1 START
test2  XYZ
test 3 ABC
test 2 START

应该打印出来

test 1 START
test 2 START

我尝试了下面的代码，但它只是开始打印

 public class Findlog{
    public static void main(String[] args) throws IOException {

    BufferedReader r = new BufferedReader(new FileReader("myfile"));
    Pattern patt = Pattern.compile(".*START$");
            // For each line of input, try matching in it.
            String line;
            while ((line = r.readLine()) != null) {
              // For each match in the line, extract and print it.
              Matcher m = patt.matcher(line);
              while (m.find()) {
                // Simplest method:
                // System.out.println(m.group(0));

                // Get the starting position of the text

                System.out.println(line.substring(line));
              }
            }

Answer 1

我想你已经找到了解决办法。 无论如何，应该起作用的正则表达式是：

".*START$"

上面写着：取后面跟START的所有（.*），START是行（$）的结尾

Answer 2

public class Findlog{
    public static void main(String[] args) throws IOException {

    BufferedReader r = new BufferedReader(new FileReader("myfile"));
    Pattern patt = Pattern.compile(".*START$");
            // For each line of input, try matching in it.
            String line;
            while ((line = r.readLine()) != null) {
              // For each match in the line, extract and print it.
              Matcher m = patt.matcher(line);
              while (m.find()) {
                // Simplest method:
                // System.out.println(m.group(0));

                // Get the starting position of the text

                System.out.println(line.substring(line));
              }
            }

Answer 3

代码的完整版本如下所示

     public class Findlog{
        public static void main(String[] args) throws IOException {

        BufferedReader r = new BufferedReader(new FileReader("myfile"));
        String line;
        while ((line = r.readLine()) != null) {
          // For each match in the line, extract and print it.
          if(line.endsWith("START"))
          {
             System.out.println(line);
          }
        }

如果您想跳过区分大小写，那么代码应该如下所示

public class Findlog{
        public static void main(String[] args) throws IOException {

        BufferedReader r = new BufferedReader(new FileReader("myfile"));
        String line;
        while ((line = r.readLine()) != null) {
          // For each match in the line, extract and print it.
          if(line.toLowerCase().endsWith(matches.toLowerCase()))
          {
             System.out.println(line);
          }
        }

只要更改if条件即可

Answer 4

line.endsWith("START")检查就足够了。这里不需要正则表达式