How to handle ZipException(Wrong password for file : Demo.zip) and display appropriate messages

Question

Since I'm new to Java, I have created a method to unzip password protected zip files, I have used zip4j library for unzipping the zip file,the code works fine when the password is correct, but when the password is wrong how to handle the ZipException(net.lingala.zip4j.exception.ZipException: net.lingala.zip4j.exception.ZipException: net.lingala.zip4j.exception.ZipException: Wrong Password for file: Demo.zip)and display appropriate message(Wrong Password!).Please Help, Here is my code.

import net.lingala.zip4j.core.ZipFile;
import net.lingala.zip4j.exception.ZipException;
import net.lingala.zip4j.model.ZipParameters;
import net.lingala.zip4j.util.Zip4jConstants;
public class UnunzipDemo{

 public void unzipFilesWithPassword(String sourceZipFilePath,String extractedZipFilePath,String password){
  try {
            ZipFile zipFile = new ZipFile(sourceZipFilePath);
            if (zipFile.isEncrypted()) {
                zipFile.setPassword(password);
            }
            zipFile.extractAll(extractedZipFilePath);
            System.out.println("Done");
        }
        catch (ZipException e) {
            e.printStackTrace();
        }
    }

 public static void main(String[] args) {
  String sourceZipFilePath="E:/MyFiles/Files/Zip/Demo.zip";
  String extractedZipFilePath="E:/MyFiles/Files/Unzip/";
  String password="JOEL"; //Correct Password
  UnunzipDemo unzipDemo=new UnunzipDemo();
  unzipDemo.unzipFilesWithPassword(sourceZipFilePath,extractedZipFilePath,password);
 }
}

Why don’t you just replace `e.printStackTrace();` with a proper error message? — Antimon, Jan 27 '19 at 13:00
If i replace those lines with proper message, it will always give me that message for all types of ZipExceptions — Joel Mathews, Jan 27 '19 at 14:52

score 0 · Accepted Answer · answered Jan 27 '19 at 13:18

Maybe you can read the password from console. For instance:

    private static String password = "123";

    public static void main(String[] args) {

        // read the input password from console
        // if you have UI, maybe you can read it from some way.
        Scanner sc = new Scanner(System.in);
        String inputPassword = sc.next();
        while (true) {
            //do something...
            try {
                unzip(inputPassword);
                break;
            } catch (Exception e) {
                inputPassword = sc.next();
            }

        }
    }

    private static void unzip(String inputPassword) {
        if (inputPassword.equals(password)) {
            //unzip
        } else {
            // just demo. In your case, this is ZipException
            throw new IllegalArgumentException("wrong password");
        }
    }

score 0 · Answer 2 · answered May 18 '19 at 08:59

You can also check the error code.

public void unzipFilesWithPassword(String sourceZipFilePath,String extractedZipFilePath,String password){
    try {
        ZipFile zipFile = new ZipFile(sourceZipFilePath);
        if (zipFile.isEncrypted()) {
            zipFile.setPassword(password);
        }
        zipFile.extractAll(extractedZipFilePath);
        System.out.println("Done");
    }
    catch (ZipException e) {
        if (e.getCode == ZipExceptionConstants.WRONG_PASSWORD) {
           // Handle wrong password scenario
           System.out.println("Wrong password");
        } else {
           //Handle other exception scenario - printing out error messages?
        }
    }

How to handle ZipException(Wrong password for file : Demo.zip) and display appropriate messages

2 Answers2