Use java's Scanner.useDelimiter() function to set the delimiter for input parsing

Use Java's Scanner.useDelimiter() function to set the delimiter for input parsing

In Java, the Scanner class is a very useful tool for reading and parsing data from user input streams. The Scanner class provides various methods to read different types of data, such as integers, floating point numbers, strings, etc. In addition, the Scanner class also provides a very useful function, the useDelimiter() function, which can be used to set the delimiter for input parsing. By setting the delimiter, we can get the required data from the input stream more flexibly.

The syntax of the Scanner.useDelimiter() function is as follows:
public Scanner useDelimiter(String pattern)

The pattern parameter is used to specify the pattern of the delimiter. Regular expressions can be used to define patterns of separators. Below is a simple example that demonstrates how to use the useDelimiter() function to set different types of delimiters.

First, we create a Java class named DelimiterExample and import the Scanner class and java.util package.

import java.util.Scanner;

public class DelimiterExample {
   public static void main(String[] args) {
      String input = "Hello;World,Java-Programming";
      Scanner scanner = new Scanner(input);
      
      // 使用分号作为分隔符
      scanner.useDelimiter(";");
      System.out.println("使用分号作为分隔符：");
      while (scanner.hasNext()) {
         System.out.println(scanner.next());
      }
      
      // 使用逗号作为分隔符
      scanner = new Scanner(input);
      scanner.useDelimiter(",");
      System.out.println("使用逗号作为分隔符：");
      while (scanner.hasNext()) {
         System.out.println(scanner.next());
      }
      
      // 使用连字符作为分隔符
      scanner = new Scanner(input);
      scanner.useDelimiter("-");
      System.out.println("使用连字符作为分隔符：");
      while (scanner.hasNext()) {
         System.out.println(scanner.next());
      }
      
      scanner.close();
   }
}

The above example code defines a string variable input, which contains some data separated by different symbols. Next, we create a Scanner object and pass input as a parameter to its constructor. Then, test using semicolons, commas, and hyphens as different delimiters.

The output of running the code is as follows:

Use semicolon as delimiter:
Hello
World,Java-Programming

Use comma as delimiter ：
Hello;World
Java-Programming

Use hyphens as separators:
Hello;World,Java
Programming

You can see that according to different delimiter, Scanner successfully parses the input stream into different fragments and outputs these fragments.

By using the Scanner.useDelimiter() function, we can easily set the delimiter for input parsing, thereby obtaining the required data more flexibly. This is useful for processing user input or parsing data from text files. In actual development, we can choose appropriate separators according to specific needs and use regular expressions to define more complex separation patterns.

In short, the Scanner.useDelimiter() function is a very useful function in Java, which provides us with a more flexible way of input parsing. By setting the delimiter, we can easily extract the required data from the input stream. I hope this article can help you better understand and use the useDelimiter() function of the Scanner class.

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