Q:

java.lang.ClassCastException: org.bouncycastle to error while creating wallet using web3j

I am using web3j to create account.
String walletFileName = WalletUtils.generateFullNewWalletFile("
<password>",new File("some/path"));

But getting this error:
java.lang.ClassCastException: org.bouncycastle.jce.provider.JCEECPrivateKey cannot be cast to org.bouncycastle.jcajce.provider.asymmetric.ec.BCECPrivateKey

My setup in pom.xml is as follows:
<dependency>
    <groupId>org.web3j</groupId>
    <artifactId>core</artifactId>
    <version>3.4.0</version>
</dependency>
<dependency>
    <groupId>org.bouncycastle</groupId>
    <artifactId>bcprov-jdk15on</artifactId>
    <version>1.54</version>
</dependency>

Please let me know where I am going wrong. 

A:

Your code seem to be OK, I just created a project and I can run it:
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>io.gjeanmart.sandbox.web3j</groupId>
    <artifactId>Web3jCreateWallet</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <properties>
        <maven.compiler.target>1.8</maven.compiler.target>
        <maven.compiler.source>1.8</maven.compiler.source>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.web3j</groupId>
            <artifactId>core</artifactId>
            <version>3.4.0</version>
        </dependency>
    </dependencies>

</project>

PS: You don't really need to add bouncycastle as dependancy as it is pull by web3j:core directly.

TestCreateWallet.java
package io.gjeanmart.stackexchange.web3j.test;

import java.io.File;
import java.io.IOException;
import java.security.InvalidAlgorithmParameterException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;

import org.junit.Test;
import org.web3j.crypto.CipherException;
import org.web3j.crypto.WalletUtils;

public class TestCreateWallet {

    @Test
    public void createWallet() throws NoSuchAlgorithmException, NoSuchProviderException, InvalidAlgorithmParameterException, CipherException, IOException {

        String folder = "/tmp/wallet/";
        String password = "secr3t";

        File folderFile = new File(folder);
        folderFile.mkdirs();

        String walletFileName = WalletUtils.generateFullNewWalletFile(password, folderFile);
        System.out.println("Wallet generated: " + walletFileName);
    }

}

Result:

Wallet generated:
  UTC--2018-12-18T16-41-35.32000000Z--cdf77e5fbee401d12f394f4f47f883407e883bd1.json

Code:
Code available on Github

