Java文件类

本文概述

• Java文件示例1
• Java文件示例2
• Java文件示例3
• Java文件示例4

File类是文件和目录路径名的抽象表示。路径名可以是绝对路径, 也可以是相对路径。

File类具有几种用于处理目录和文件的方法, 例如创建新目录或文件, 删除和重命名目录或文件, 列出目录内容等。

领域

建设者

有用的方法

Java文件示例1

import java.io.*;
public class FileDemo {
	public static void main(String[] args) {

		try {
			File file = new File("javaFile123.txt");
			if (file.createNewFile()) {
				System.out.println("New File is created!");
			} else {
				System.out.println("File already exists.");
			}
		} catch (IOException e) {
			e.printStackTrace();
		}

	}
}

输出：

New File is created!

Java文件示例2

import java.io.*;
public class FileDemo2 {
	public static void main(String[] args) {

		String path = "";
		boolean bool = false;
		try {
			// createing  new files
			File file  = new File("testFile1.txt");
			file.createNewFile();
			System.out.println(file);
			// createing new canonical from file object
			File file2 = file.getCanonicalFile();
			// returns true if the file exists
			System.out.println(file2);
			bool = file2.exists();
			// returns absolute pathname
			path = file2.getAbsolutePath();
			System.out.println(bool);
			// if file exists
			if (bool) {
				// prints
				System.out.print(path + " Exists? " + bool);
			}
		} catch (Exception e) {
			// if any error occurs
			e.printStackTrace();
		}
	}
}

输出：

testFile1.txt
/home/Work/Project/File/testFile1.txt
true
/home/Work/Project/File/testFile1.txt Exists? true

Java文件示例3

import java.io.*;
public class FileExample {
public static void main(String[] args) {
	File f=new File("/Users/sonoojaiswal/Documents");
	String filenames[]=f.list();
	for(String filename:filenames){
		System.out.println(filename);
	}
}
}

输出：

"info.properties"
"info.properties".rtf
.DS_Store
.localized
Alok news
apache-tomcat-9.0.0.M19
apache-tomcat-9.0.0.M19.tar
bestreturn_org.rtf
BIODATA.pages
BIODATA.pdf
BIODATA.png
struts2jars.zip
workspace

Java文件示例4

import java.io.*;
public class FileExample {
public static void main(String[] args) {
	File dir=new File("/Users/sonoojaiswal/Documents");
	File files[]=dir.listFiles();
	for(File file:files){
		System.out.println(file.getName()+" Can Write: "+file.canWrite()+" 
		Is Hidden: "+file.isHidden()+" Length: "+file.length()+" bytes");
	}
}
}

输出：

"info.properties" Can Write: true Is Hidden: false Length: 15 bytes
"info.properties".rtf Can Write: true Is Hidden: false Length: 385 bytes
.DS_Store Can Write: true Is Hidden: true Length: 36868 bytes
.localized Can Write: true Is Hidden: true Length: 0 bytes
Alok news Can Write: true Is Hidden: false Length: 850 bytes
apache-tomcat-9.0.0.M19 Can Write: true Is Hidden: false Length: 476 bytes
apache-tomcat-9.0.0.M19.tar Can Write: true Is Hidden: false Length: 13711360 bytes
bestreturn_org.rtf Can Write: true Is Hidden: false Length: 389 bytes
BIODATA.pages Can Write: true Is Hidden: false Length: 707985 bytes
BIODATA.pdf Can Write: true Is Hidden: false Length: 69681 bytes
BIODATA.png Can Write: true Is Hidden: false Length: 282125 bytes
workspace Can Write: true Is Hidden: false Length: 1972 bytes