How to use the Scanner function in Java for file reading operations

In Java, the Scanner function is a very useful function that can help us read data files and other input sources. In this article, we will focus on how to use the Scanner function for file reading operations.

1. Create Scanner Object

First, we need to create a Scanner object to read our file. We can create a file reader by passing the file path, for example:

Scanner scanner = new Scanner(new File("file.txt"));

This will create a Scanner object named "scanner" which will read from the file named "file.txt" Get data.

2. Read the entire line

Now, we can use the Scanner object to read the data in the file. We can read a line of data using the nextLine() function, for example:

String line = scanner.nextLine();

This will return the next line of text in the file. We can assign it to a string variable called "line".

3. Read integers and floating point numbers

If we need to read numbers in the file, we can use the nextInt() function to read integers or useNextDouble() function to read Take a floating point number, for example:

int num = scanner.nextInt();
double dnum = scanner.nextDouble();

This will return the next integer or floating point number in the file respectively. We can assign them to an integer variable named "num" or assign them to a floating point variable named "dnum".

4. Read the value of a specific delimiter

If the data in the file uses a specific delimiter to separate values ​​such as numbers and text, we can use the useDelimiter() function to specify the delimiter. For example, if our data file uses commas as delimiters:

scanner.useDelimiter(",");

This will instruct the Scanner object to treat commas as delimiters so that the data in the file can be read correctly.

5. Close the Scanner object

When we complete the file reading operation, we should close the Scanner object. This can be achieved by calling the close() function, for example:

scanner.close();

This will close the Scanner object and release the resources associated with it, such as open files.

Summary:

By using the Scanner function in Java, we can easily read the data in the file. We can use the nextLine() function to read the entire line, use the nextInt() and useNextDouble() functions to read the numbers, use the useDelimiter() function to specify a specific delimiter, and finally, make sure to call close() after completing the file reading operation. Function to close the Scanner object.

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