How to use Scanner in java

Scanner is a tool in Java that reads data from input sources. To use a Scanner, perform the following steps: Create a Scanner object: Use the new Scanner statement to specify the input source. Reading data: Use the hasNext method to check if the next element exists, then use the appropriate next method to read the data element. Close Scanner: Release the resources associated with the Scanner object. Scanner provides a variety of methods to handle various data types, including integers, strings, and floating point numbers. The sample code demonstrates how to read an integer from the keyboard. Always remember to close the Scanner object.

Usage of Scanner in Java

What is Scanner?

Scanner is a tool in Java for reading data from an input source such as keyboard, file, or string. It provides a simple and convenient way to read various data types such as integers, strings, and floating point numbers element-by-element.

Using Scanner

To use Scanner, perform the following steps:

1. Create a Scanner object: Use the new Scanner statement to specify the input source. For example:

   Scanner scanner = new Scanner(System.in);

2. Reading data: Use the hasNext method to check if the next element exists, then use the appropriate next Methods (such as nextInt, nextLine) read data elements. For example:

   while (scanner.hasNext()) {
    String line = scanner.nextLine();
    // 对 line 进行处理
   }

3. Close Scanner: Use the close method to release the resources associated with the Scanner object. For example:

   scanner.close();

Available methods

Scanner provides the following methods to handle various data types:

• nextBoolean
• nextByte
• nextDouble
• ##nextFloat
• nextInt
• nextLong
##nextLine
nextShort

Example

The following example shows how to use Scanner to read integers from the keyboard:

import java.util.Scanner;

public class ScannerDemo {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter an integer: ");
        int number = scanner.nextInt();
        System.out.println("Entered integer: " + number);
        scanner.close();
    }
}

Tip

For floating point numbers, you can use

nextDouble
• , which will automatically parse the input into double. For strings, you can use
nextLine
• , which will read until a newline character is encountered. Always remember to close the Scanner object to release resources.

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