How to use sanner in java

The Scanner class is used to read input data from the input stream. Its usage is as follows: Create a Scanner object. Use the Scanner method to read different types of data. Process the input data. Close the Scanner object.

Using Scanner in Java

Introduction

The Scanner class is a class in Java that is used to read raw input from an input stream (such as the keyboard, a file, or a network connection) .

Usage

1. Create a Scanner object

Scanner scanner = new Scanner(InputStream);

whereInputStream can beSystem.in (for reading from the keyboard), file, or network connection.

2. Read input

You can use various methods provided by the Scanner object to read different types of data from the input stream:

• nextInt()：Read the next integer
• nextDouble()：Read the next double Precision floating point number
• nextLine()：Read a line of text
• hasNext()：Check if more input is available

3. Process input

After reading the input, you can use Java conditional statements or loops to process the input .

4. Close the Scanner object

After using the Scanner object, you should close it to release resources:

scanner.close();

Sample code

// 从键盘读取一行文本
Scanner scanner = new Scanner(System.in);
String input = scanner.nextLine();

// 从文件中读取整数
File file = new File("numbers.txt");
Scanner fileScanner = new Scanner(file);
int number = fileScanner.nextInt();

// 从网络连接读取双精度浮点数
URL url = new URL("http://example.com/data.txt");
Scanner networkScanner = new Scanner(url.openStream());
double value = networkScanner.nextDouble();

// 关闭 Scanner 对象
scanner.close();
fileScanner.close();
networkScanner.close();

Notes

• Make sure the input stream is open and data is available.
• Use the hasNext() method correctly to check the availability of input and avoid null pointer exceptions.
• When processing input, consider data type mismatch or input format error.
• Close the Scanner object promptly to release resources.

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