如何通过逐行读取文件来获取上一行

Question

我正在使用扫描程序逐行读取文件。所以我的问题是，我们如何能够将前一行并排存储，因为我们继续前进到下一行。

while (scanner.hasNextLine()) { 
    line = scanner.nextLine();//this will get the current line 
    if (line.contains("path=/select")){ 
    // So whenever I enter in this if loop or this loop is true, I also want to 
    have the previous line in any String variable. How can we achieve this? 
    } 

任何建议，将不胜感激。

Answer 1

String previousLine = null; 
while (scanner.hasNextLine()) { 
    String line = scanner.nextLine(); 
    if (line.contains("path=/select")) { 
     // use previousLine here (null for the first iteration or course) 
    } 
    previousLine = line; 
} 

Answer 2

prevLine = null; // null indicates no previous lines 

while (scanner.hasNextLine()) { 
    line = scanner.nextLine(); //this will get the current line 
    if (line.contains("path=/select") && prevLine != null){ 
     // ... 
    } 
    prevLine = line; 
} 

我假设，如果没有前行，那么你就不会想要进入if块。