Java 如何查找特定字符串后面的特定行？

Question

我从 BufferedReader 获取了一条文本，我需要在特定字符串之后获取特定行

这是示例文本:

<img src="https://example.com/image1.jpg">
<img src="https://example.com/image2.jpg">
<img src="https://example.com/image3.jpg">
<img src="https://example.com/image4.jpg">
<all>
<img src="https://example.com/image9.jpg">
<img src="https://example.com/image11.jpg">
<img src="https://example.com/image15.jpg">

带换行符的示例

<img src="https://example.com/image1.jpg">
<img src="https://example.com/image2.jpg">
<img src="https://example.com/image3.jpg">
<img src="https://example.com/image4.jpg">
<all>

<img src="https://example.com/image9.jpg">
<img src="https://example.com/image11.jpg">
<img src="https://example.com/image15.jpg">

其他角色的示例

<img src="https://example.com/image1.jpg">
<img src="https://example.com/image2.jpg">
<img src="https://example.com/image3.jpg">
<img src="https://example.com/image4.jpg">
<all>
UTUYGBLK
<img src="https://example.com/image9.jpg">
<img src="https://example.com/image11.jpg">
<img src="https://example.com/image15.jpg">

我只想要“all”之后的 img src 行，其中 cont 和 end 循环之后。图像编号是随机的，所以我不可能击中其中任何一个。

目前我的代码如下。

while ((line = rd.readLine()) != null) {

  if (line.contains("all"))  {    
    line = rd.readLine();   
    System.out.println(line);
  }
 }

但是如果“all”后面有一个换行符，我将得到一个空返回...或有趣的字符 UTUYGBLK

Answer 1

您需要在该元素之后循环，直到结果不为空。下面的代码应该防止您在文件结尾后读取行，并且在读取后显示第一行后停止。

boolean loop = true;
// global loop
while ((line = rd.readLine()) != null && loop) {
  // line with "all" in it is found?
  if(line.contains("all"))  {    
    // Continue going through the input until end of input
    while((line = rd.readLine()) != null && loop) {  
      // When the line is not empty you have found the line after all!
      if(!line.isEmpty()) {
        System.out.println(line);
        // to stop the loops
        loop = false; 
      }
    }
  }
}