获取java

Question

我想要在文本文件

中最后一次出现特定字符串的行

Scanner file = new Scanner(new File("C:\\Users\\prudra\\Desktop\\Axalta\\20180406114505\\activemq.log_app1"));
int i = 0;
String str = file.nextLine();
System.out.print("Enter search ");
Scanner sc = new Scanner(System.in);
System.out.println("Enter the environment you want to execute the script (Dev/QA/Prod)");
String name = sc.nextLine();
while (file.hasNextLine()) {
 final String lineFromFile = file.nextLine();
 i++;
 if (lineFromFile.contains(name)) {
  //System.out.println("file.txt");
 }
}
System.out.println(i);
}

Answer 1

如果我理解正确你想要这样的东西吗？

int lastIndex= 0;
//start of loop
if (lineFromFile.contains(name)) {
  lastIndex = i;
}

//end of loop

if (lastIndex != 0) {
    System.out.println(lastIndex);
} else {
    System.out.println("Line not found");
}

或者只是在条件中递增i

int i = 0;
//start of loop
if (lineFromFile.contains(name)) {
  i++;
}

//end of loop

if (i != 0) {
    System.out.println(i + 1); //because you start i from 0
} else {
    System.out.println("Line not found");
}

Answer 2

Scanner file = new Scanner(new File("C:\\Users\\prudra\\Desktop\\Axalta\\20180406114505\\activemq.log_app1"));
int i = 0;
int index = 0;
String str = file.nextLine();
System.out.print("Enter search ");
Scanner sc = new Scanner(System.in);
System.out.println("Enter the environment you want to execute the script (Dev/QA/Prod)");
String name = sc.nextLine();
while (file.hasNextLine()) {
 final String lineFromFile = file.nextLine();
 i++;
 if (lineFromFile.contains(name)) {
  //saves index of occurance
  index = i;
 }
}
System.out.println(index);
}

我想这就是你要找的东西。只需要一个变量来保存最后一次出现的行。由于你只想要最后一行，所以读完所有行index将保留最后一行。如果你想要第一个，你可以在找到第一个后返回i。如果你需要x出现，你需要在另一个变量中保持计数。

编辑：不确定行是否表示行文本的行号，如果是文本，而不是使用索引来保存行号，则可以使用字符串来保存行文本，如lineText = lineFromFile;

Answer 3

将最后一行存储在局部变量中并在循环外访问它。

示例：

 Scanner file = new Scanner(new File("C:\\Users\\prudra\\Desktop\\Axalta\\20180406114505\\activemq.log_app1"));
int i = 0;
String str = file.nextLine();
System.out.print("Enter search ");
Scanner sc = new Scanner(System.in);
System.out.println("Enter the environment you want to execute the script (Dev/QA/Prod)");
String name = sc.nextLine();
String lastLine="";
int lastLineNumber=-1;
while (file.hasNextLine()) {
 final String lineFromFile = file.nextLine();
 i++;
 if (lineFromFile.contains(name)) {
   lastLine=lineFromFile;
   lastLineNumber=i;
  //System.out.println("file.txt");
 }
}
System.out.println(i);
System.out.println("Last Line: "+lastLine);
System.out.println("Last Line Number: "+lastLineNumber);
}

只要文件指针从第一行开始读取到文件的最后一行，这实际上就有效。因为在循环结束时，您将存储所需文本行的最后一次出现，然后您可以稍后访问它。