The “File” class in Java defines many useful methods, here is a program which demonstrates some of these methods.
import java.io.*; public class streams{ public static void main(String []args) { File f1=new File("Folder/FILE"); File f2=new File("Folder/FILE1"); String s; if(f1.exists()) { if(f1.isFile()) { System.out.println("File Name is "+f1.getName()); s=f1.getParent(); File f3=new File(s); f1.renameTo(new File("Folder/abc")); f2.delete(); if (f3.isDirectory()) { System.out.println(f2.getPath()); } } else { System.out.println("Not a File"); } } }}The output of the program is: File Name is FILEFolder If successfully run , the ” FILE ” file inside the folder ” Folder ” will be renamed to ” abc ” and the ” FILE1 ” file will be deleted.
Here is an example of a program that reads its own first six bytes, we have:
//0123 import java.io.*; public class read{ public static void main(String []args) { int s=6; int b[]=new int[6]; char c[]=new char[6]; try { FileInputStream f = new FileInputStream("read.java"); for (int i=0; i<6; i++) { b[i] = f.read(); c[i] = (char) b[i]; } System.out.println("First 6 bytes of the file are :"); for (int i=0;i<6;i++) System.out.print(b[i]+" "); System.out.println("nnFirst 6 Bytes as characters :"); for (int i=0;i<6;i++) System.out.print(c[i]); } catch (Exception e) { System.out.println("Error"); } }} This program produces the following output: First 6 bytes of the file are :47 47 48 49 50 51 First 6 Bytes as characters are : //0123 Notice that the FileInputStream object is created inside a try-catch block since if the specified-file does not exist, an exception is raised.
In the same way to write data to a file byte-by-byte, we have:
import java.io.*; public class witer{ public static void main(String []args) throws IOException { String s="Hello"; byte b[]=s.getBytes(); FileOutputStream f=new FileOutputStream("file.txt"); int i=0; while(i { f.write(b[i]); i++; } }} If the file called file.txt does not exist, it is automatically created.
If we place a true in the constructor for the FileOutputStream, then the file would be opened in append mode.
Note: All file paths used here are relative paths , Use absolute path or add the relative path to the classpath, Copy the folders to the bin folder版权声明：本文为博主原创文章，未经博主允许不得转载。