Java I/O How to - Use Scanner to read several different unknown types of data

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Question

We would like to know how to use Scanner to read several different unknown types of data.

Answer

import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;
/*from ww w. j ava 2s.c o m*/
public class MainClass {
  public static void main(String args[]) throws IOException {
    // Write output to a file.
    FileWriter fout = new FileWriter("test.txt");
    fout.write("int: 1  double 1.0  boolean true");
    fout.close();

    FileReader fin = new FileReader("Test.txt");

    Scanner src = new Scanner(fin);

    while (src.hasNext()) {
      if (src.hasNextInt()) {
        System.out.println("int: " + src.nextInt());
      } else if (src.hasNextDouble()) {
        System.out.println("double: " + src.nextDouble());
      } else if (src.hasNextBoolean()) {
        System.out.println("boolean: " + src.nextBoolean());
      } else {
        System.out.println(src.next());
      }
    }
    fin.close();
  }
}

The code above generates the following result.

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