从 Java 中的文件读取字符串时如何跳过字符

Question

For example, the content of a file is:

black=white

bad=good

easy=hard

So, I want to store in a map this words as key and value (ex: {black=white, bad=good} ). And my problem is when I read string I have to skip a char '=' which disappears key and value. How to make this?

In code below I make a code which read key and value from file, but this code works just when between words is SPACE, but I have to be '='.

System.out.println("File name:");
    String pathToFile = in.nextLine();
    File cardFile = new File(pathToFile);
    try(Scanner scanner = new Scanner(cardFile)){
        while(scanner.hasNext()) {
            key = scanner.next();
            value = scanner.next();
            flashCards.put(key, value);
        }
    }catch (FileNotFoundException e){
        System.out.println("No file found: " + pathToFile);
    }

Answer 1

Use the split method of String in Java.

so after reading your line, split the string and take the key and value as so.

String[] keyVal = line.split("=");
System.out.println("key is ", keyVal[0]);
System.out.println("value is ", keyVal[1]);

Answer 2

You can change the delimiter for the scanner.

public static void main (String[] args) throws java.lang.Exception
{
    String s = "black=white\nbad=good\neasy=hard";
    Scanner scan = new Scanner(s);
    scan.useDelimiter("\\n+|=");
    while(scan.hasNext()){
        
        String key = scan.next();
        String value = scan.next();
        System.out.println(key + ", " + value);
    }
}

The output:

black, white
bad, good
easy, hard

Changing the delimiter can be tricky, and it could be better to just read each line,then parse it. For example, "\\n+|=" will split the tokens by either one or more endlines, or an "=". The end line is somewhat hard coded though so it could change depending on the platform the file was created on.

Answer 3

A simple "if" condition will solve it.

if (key == '='){ break;}