使用扫描器类在 Java 中读取字符串输入的问题

Question

I'm pretty much a complete newbie when it comes to Java. I've dabbled a bit in python and VB.net, and that's about it.

I'm trying to write a program in java that literally reads the user's input and displays it back to them with this code:

import java.util.Scanner;

public class InputTesting
{   
    public static void main( String[] args )
    {
        Scanner input = new Scanner ( System.in );

        String str1;

        System.out.println("Input string: ");

        str1 = input.nextString();

        System.out.println( str1 );
    }
}

And I get the error:

InputTesting.java:13: error: cannot find symbol
        str1 = input.nextString();
                    ^
  symbol:   method nextString()
  location: variable input of type Scanner
1 error

Can someone tell what why it's not compiling? Thanks!

Answer 1

input.nextString();

There is no method called nextString in the Scanner class. That's why you're getting the error cannot find symbol .

Try

input.nextLine(); // If you're expecting the user to hit enter when done.
input.next(); // Just another option.

Answer 2

import java.util.Scanner;

public class InputTesting
{   
    public static void main( String[] args )
    {
        Scanner input = new Scanner ( System.in );

         String str1;

        System.out.println("Input string: ");

            str1 = input.next();

        System.out.println( str1 );
    }
}

Answer 3

You may use one of input.nextXXX() as detailed in Scanner javadoc . to resolve compiler error

in your case

you may use input.nextLine(); get entire line of text.

By Default whitespace delimiter used by a scanner. However If you need to scan sequence of inputs separated by a delimiter useDelimiter can be used to set regex delim

public static void main(String[] args) {
    try (Scanner input = new Scanner(System.in);) {
        input.useDelimiter(";");
        while (input.hasNext()) {
            String next = input.next();
            if ("DONE".equals(next)) {
                break;
            }
            System.out.println("Token:" + next);
        }
    }
}

Input

1a;2b;3c;4d;5e;DONE;

Output

Token:1a
Token:2b
Token:3c
Token:4d
Token:5e

Just be cautious while scanning decimal and signed numbers as scanning is Locale Dependent

Answer 4

You need to rather use method nextLine() . This methods prints entire line. By using next() it will print only one word in your sentence.

Answer 5

// That's how i managed solution for input a string

import java.util.Scanner; public class PalindromeWord {

public static void main(String[] args) {
    
    //System.out.println("Enter a string: ");
    Scanner input = new Scanner(System.in);
    


     String S = input.next(); 
     String reverseStr = "";
    
    int strLength = S.length();

    for (int i = (strLength - 1); i >=0; --i) {
      reverseStr = reverseStr + S.charAt(i);
    }

    if (S.equals(reverseStr)) {
      System.out.println("Yes");
    }
    else {
      System.out.println("No");
    }

}

}