feat(examples): update GenerateKeyExample to use ECDSA (#2700)

Signed-off-by: Ndacyayisenga-droid <ndacyayinoah@gmail.com>

Author: Ndacyayisenga-droid

examples/src/main/java/com/hedera/hashgraph/sdk/examples/GenerateKeyExample.java

@@ -1,25 +1,34 @@
 // SPDX-License-Identifier: Apache-2.0
 package com.hedera.hashgraph.sdk.examples;
 
+import com.hedera.hashgraph.sdk.EvmAddress;
 import com.hedera.hashgraph.sdk.PrivateKey;
 import com.hedera.hashgraph.sdk.PublicKey;
 
 /**
- * How to generate ED25519 key pair.
+ * How to generate an ECDSA (secp256k1) key pair and derive the EVM address from the public key.
+ *
+ * <p>ECDSA keys with an EVM address derived from the public key are the recommended choice for new
+ * Hedera accounts when you want compatibility with Ethereum tooling (wallets, Hardhat, ethers.js,
+ * etc.). For legacy Hedera-only flows you can still use {@link PrivateKey#generateED25519()}.
  */
 class GenerateKeyExample {
 
     public static void main(String[] args) {
-        System.out.println("Generate ED25519 Private And Public Key Pair Example Start!");
+        System.out.println("Generate ECDSA key pair and EVM address example start");
 
-        System.out.println("Generating the ED25519 private key...");
-        PrivateKey privateKey = PrivateKey.generateED25519();
-        System.out.println("Private Key: " + privateKey);
+        System.out.println("Generating an ECDSA (secp256k1) private key...");
+        PrivateKey privateKey = PrivateKey.generateECDSA();
+        System.out.println("Private key: " + privateKey);
 
-        System.out.println("Deriving a public key from the above private key");
+        System.out.println("Deriving the public key from the private key");
         PublicKey publicKey = privateKey.getPublicKey();
         System.out.println("Public key: " + publicKey);
 
-        System.out.println("Generate ED25519 Private And Public Key Pair Example Complete!");
+        System.out.println("Deriving the EVM address (last 20 bytes of Keccak-256 of the uncompressed public key)");
+        EvmAddress evmAddress = publicKey.toEvmAddress();
+        System.out.println("EVM address: 0x" + evmAddress);
+
+        System.out.println("Generate ECDSA key pair and EVM address example complete");
     }
 }