Common methods of file class

  

 

 

package File;

import org.junit.Test;

import java.io.File;
import java.util.Date;

public class FileMethod {
    @Test
    public void test1(){
        File file1 = new File("hello.txt");
        File file2 = new File("D:\\java project\\day07\\he.txt");

        System.out.println(file1.getAbsoluteFile());
        System.out.println(file1.getPath());
        System.out.println(file1.getName());
        System.out.println(file1.getParent());
        System.out.println(file1.length());
        System.out.println(new Date(file1.lastModified()));
        System.out.println("************");
        System.out.println(file2.getAbsoluteFile());
        System.out.println(file2.getPath());
        System.out.println(file2.getName());
        System.out.println(file2.getParent());
        System.out.println(file2.length());
        System.out.println(file2.lastModified());
    }
    @Test
    public void test2(){
//         The following two methods apply to file directories ：
//        public String[] list()： Gets the name array of all files or file directories in the specified directory （ In the way of relative path ）
//        public File[] listFiles()： Get all files or file directories in the specified directory File Array ( In the form of absolute path )

        File file = new File("D:\\java project");
        String[] list = file.list();
        for(Object obj : list){
            System.out.println(obj);
        }
        File[] listFiles = file.listFiles();
        for(Object obj:listFiles){
            System.out.println(obj);
        }
    }
    @Test
    public void test3(){
        //        public boolean renameTo(File dest)  Rename the file to the specified file path 
//           With file1.renameTo(file2) For example 
//         To ensure return true, need file1 There is ,file2 Does not exist in the hard disk 
        File file1 = new File("hello.txt");
        File file2 = new File("D:\\java project\\day07\\src\\File\\hi.txt");
        boolean renameTo = file1.renameTo(file2);
        System.out.println(renameTo);

    }
}

  Files already in the hard disk , stay new file Object time , The corresponding values in memory will be assigned

No documents , When new file Object time , The corresponding values in memory are all default values .

package File;

import org.junit.Test;

import java.io.File;
import java.io.IOException;

public class FileMethod2 {
    @Test
    public void test1(){
        File file1 = new File("D:\\java project\\day07");
        System.out.println(file1.isDirectory());
        System.out.println(file1.isFile());
        System.out.println(file1.exists());
    }

    @Test
    public void test2() throws IOException {
        File file1 = new File("hello.txt");

//         File creation 
        if(!file1.exists()){
            file1.createNewFile();    // It is equivalent to creating a new 
            System.out.println(" Create success ");
        }else {
            file1.delete();
            System.out.println(" Delete successful ");
        }
    }
    @Test
    public void test3(){
        //         File directory creation 
        File file1 = new File("F:\\test\\io2\\io1");
        boolean mkdir = file1.mkdir();
        if(mkdir){
            System.out.println(" create a file 1 Object success ");
        }

        File file2 = new File("F:\\test\\io2\\io3");
        boolean mkdirs = file2.mkdirs();
        if(mkdirs){
            System.out.println(" create a file 2 Object success ");
        }
    }
}