Java find WithinHorizon方法返回null

在文件中搜索字符串“$DATA ASCII”时，我的findWithinHorizon方法返回null。同样的方法可以找到其他字符串，如“Array Start”

这是我搜索文件的代码：

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.util.Scanner;

public class SearchingFilesMain {

public static void main(String[] arg) {

    String checker;
    String pattern1= "$DATA ASCII";

    try {
        Scanner scan = new Scanner(new BufferedReader(new FileReader(
                "C:\\Users\\User\\Desktop\\asciiTracks.txt")));
        checker = scan.findWithinHorizon(pattern1,0);
        System.out.println(checker);


    } catch (FileNotFoundException e) {
        System.out.println(e.getStackTrace());
    }}}

这是文件的一部分，如记事本++中所示：

$DATA ASCII

$DATA_INFO
Array Start                     = 0 * 126
$PROCESSING_INFO
Generation Time                 = 13:53:42
$GENERAL
Tx Time                         = 450.079
Tx Time Abs                     = 1080309222.55633
Tx Clock                        = 13:53:42
Cerb Tracker Whole Time         = 0.015
Num contacts                    = 699
$DATA ASCII

$DATA_INFO
Array Start                     = 0 * 127
$PROCESSING_INFO
Generation Time                 = 13:53:45
$GENERAL
Tx Time                         = 453.219
Tx Time Abs                     = 1080309225.69626
Tx Clock                        = 13:53:45
Cerb Tracker Clutter processing = 0.016
Cerb Tracker Whole Time         = 0.016
Num contacts                    = 666
$DATA ASCII

---

我不知道为什么then方法无法搜索此代码以查找“$DATA ASCII”，有人能想到任何原因吗？

$

是正则表达式中的元字符，用于表示字符串的结尾。它需要逃脱

String pattern1 = "\\$DATA ASCII";