Use java's File.exists() function to determine whether the file exists

Use Java's File.exists() function to determine whether a file exists

In Java programming, file operations are often involved, and determining whether a file exists is one of the most common requirements. Java provides the File class to handle file and directory operations, which includes the exists() function, which can be used to determine whether a file exists.

File.exists() function is a method of the File class, used to determine whether the file or directory under the specified path exists. It will return a Boolean value. If the file or directory exists, it returns true, otherwise it returns false.

The following is a code example that uses the File.exists() function to determine whether a file exists:

import java.io.File;

public class FileExistsExample {
    public static void main(String[] args) {
        String filePath = "C:\path\to\file.txt";
        File file = new File(filePath);
        
        if (file.exists()) {
            System.out.println("文件存在");
        } else {
            System.out.println("文件不存在");
        }
    }
}

In the above code, we first specify a file path filePath, and then pass the File class The constructor creates a File object. Next, we use the exists() function to determine whether the file exists, and output the corresponding prompt information based on the determination result.

It should be noted that before using the exists() function, you need to ensure that the file path is correct. Otherwise, the exists() function will return false even if the file actually exists.

In addition, the exists() function can also be used to determine whether a directory exists. If we want to determine whether a directory exists, we only need to pass the directory path into the File object.

The following is a code example that uses the File.exists() function to determine whether a directory exists:

import java.io.File;

public class DirectoryExistsExample {
    public static void main(String[] args) {
        String directoryPath = "C:\path\to\directory";
        File directory = new File(directoryPath);
        
        if (directory.exists()) {
            System.out.println("目录存在");
        } else {
            System.out.println("目录不存在");
        }
    }
}

Similarly, we first specify a directory path directoryPath, and then create a File object. Next, we use the exists() function to determine whether the directory exists, and output the corresponding prompt information based on the determination result.

To summarize, using Java's File.exists() function can easily determine whether a file or directory exists. Whether it is to judge before reading a file or to judge before creating a directory, the exists() function is a very practical method.

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