How to create a file

[Alpha]

I need to create a file on disk and write to it. How can i do this with Java?

[FaRuK]

Hello Alpha,

You can use the following code to create a file:

try {
        File file = new File("filename");
    
        // Create file if it does not exist
        boolean success = file.createNewFile();
        if (success) {
            // File did not exist and was created
        } else {
            // File already exists
        }
    } catch (IOException e) {
    }

And for reading from or writing to the file, you can use following tips:

Java Tips - How to Read File in Java
Java Tips - How to write file in Java

[Alpha]

Thanks Faruk, this is exactly what i want.

[Torstein99]

i am having the same problem but im trying to make it in a specifick directory(C:\Users\tv\AppData\Roaming\MS2-torsteinv\MS2-dat\CD.txt) and it promts out that the directory dosent exists! cant it just make it?how can i solve this problem?

[clydedoris]

as it was saying, the directory doesn't exist. what kind of file would you even be creating on that directory?

[Torstein99]

i am making a installer to my game but do i have to create the directory first maybe?

[quad64bit]

i am making a installer to my game but do i have to create the directory first maybe?

Could be. The mkdirs() method on the File class will do this for you! Take a look at it on the File page of the java api.

[Torstein99]

ok i have used your mkdirs soulution but it semms as if i got no access. here is my code if its useful to fixing my problem:


Downloader.java

 import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Scanner;


public class Downloader {
	public static void DownloadFile(String Indir,String Outdir,String Inname,String Outname) throws MalformedURLException, IOException{
		InputStream Input = new URL(Indir+"/"+Inname).openStream();
		if(new File(Outdir+"/"+Outname).exists()){
			new File(Outdir+"/"+Outname).delete();
		}
		File f = new File(Outdir);
		f.mkdirs();
		OutputStream Output = new FileOutputStream(Outdir+"/"+Outname);
		Scanner scan = new Scanner(Input);
		while(scan.hasNext()){
			byte[] bytes = scan.nextLine().getBytes();
			Output.write(bytes, 0, bytes.length);
		}
		Input.close();
		Output.close();
	}
}

Launcher.java

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Scanner;

import javax.swing.JOptionPane;


public class Launcher{
	private static final String dir = "http://tv-w7:8000/";
	
	public static void main(String[] args){	
		new Launcher(args);
	}
	public Launcher(String[] args){
		if(args.length==1){if(args[0].equals("f")){
			try {
					JOptionPane.showMessageDialog(null, "game is getting cleaned, press OK to proseed");
					DownloadNewVersion(false,false);
				} catch (IOException e1) {
					e1.printStackTrace();
				}
			}
		}else{
			try {
				
				Download();
				
			} catch (MalformedURLException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
	public void Download() throws MalformedURLException, IOException{
		if(new File(System.getenv("APPDATA")+"/MS2-torsteinv/MS2-bin/no/torsteinv/MarsSettlement2/Client/Client.class").exists()){
			InputStream AVIS = new URL(dir+"MS2-dat/CD.txt").openStream();
			InputStream CVIS = new FileInputStream(System.getenv("APPDATA")+"/MS2-torsteinv");
			
			Scanner CVS = new Scanner(CVIS);
			Scanner AVS = new Scanner(CVIS);
			
			String CV = CVS.nextLine();
			String AV = AVS.nextLine();
			
			CVIS.close();
			AVIS.close();
			
			if(!CV.equals(AV))DownloadNewVersion(true,true);
		}else{
			DownloadNewVersion(true,false);
		}
	}
	private void DownloadNewVersion(boolean promt,boolean N) throws IOException {
		if(promt && N)if(JOptionPane.showConfirmDialog(null,"A new verson is avalible. Download?")==1);
		Runtime.getRuntime().exec("java -classpath "+System.getenv("APPDATA")+"/MS2-torsteinv");
		Scanner scan = new Scanner(new URL(dir+"MS2-register.txt").openStream());
		String CL = "";
		while(scan.hasNext()){
			CL = scan.nextLine();
			Downloader.DownloadFile(dir+CL.split(":")[0],System.getenv("APPDATA")+"/MS2-torsteinv/"+CL.split(":")[0],CL.split(":")[1],CL.split(":")[1]);
		}
		start();
	}
	private void start(){
		try {
			Runtime.getRuntime().exec("java "+System.getenv("APPDATA")+"/MS2-torsteinv/MS2-bin/no/torsteinv/MarsSettlement2/Client/Client.class");
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		System.exit(0);
	}
}