daubac402

import java.util.*; 

public class MyClass {
  public static void main(String args[]) {
    ArrayList<String> a = new ArrayList<>();

    add1(a,"1");
    System.out.println("a:" + a); // Guess the output
    
    add2(a,"2");

daubac402

Setup WDS on TpLink Archer C6

Prerequisite

BOTH root router and WDS router need to support WDS.
No need to do anything on the root router, just need to setup on the WDS router. From now, everything just on this router.

Steps on WDS router

1. Set IP address of the WDS router: Advanced > Network > LAN > IP Address. (default: 192.168.0.1. If root router is 192.168.1.1, then you can set this WDS router IP to be: 192.168.1.2). Restart.
2. Turn off DHCP server: Advanced > Network > DHCP Server > Uncheck enable > Save
3. Go to Advanced > System Tools > System Parameters

daubac402

How to fix podman machine stuck on "Currently starting"

1. Find the file ~/.config/containers/podman/machine/applehv/<your podman machine name>.json (In my case: podman-machine-default.json)
2. Near the end of the file, change "Starting":true to "Starting":false
3. Back to your Podman and restart it.

daubac402

NextCloud in Snap in Raspberry Pi tips

Installation

sudo apt-get update
sudo apt-get upgrade

sudo apt install snapd

daubac402

Liquibase CLI notes

Installation

https://www.liquibase.com/download

Preparation

Download database driver (.jar file) then put it in /your_liquibase_installation_path/lib

daubac402

Make Java project works with Self-signed certificate in IntelliJ

Problem

Your company is using a proxy to decrypt the HTTPS in between. It has a self-signed certificate. You will get this kind of Exception when sending a HTTPS request if your Java project doesn't have that self-signed certificate in its CaCerts

detailed message sun.security.validator.ValidatorException: PKIX path building failed:
sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

daubac402

Make Github copilot works with self-certificate in IntelliJ (Windows)

Problem

You can't login to Github to use Github Colpilot in your IntelliJ due to you are using self-certificate.
And you got this error message

Sign in failed. Reason: Request signInInitiate failed with message: self signed certificate in certificate chain, request id: 3, error code: -32603

daubac402

Git revert to a previous tag then push to origin:master

There are 2 ways to do that

Reset the HEAD then force push to remote

$ git checkout master
$ git pull
$ git reset --hard tag_ABC

daubac402

UPDATE (March 2020, thanks @ic): I don't know the exact AMI version but yum install docker now works on the latest Amazon Linux 2. The instructions below may still be relevant depending on the vintage AMI you are using.

Amazon changed the install in Linux 2. One no-longer using 'yum' See: https://aws.amazon.com/amazon-linux-2/release-notes/

Docker CE Install

sudo amazon-linux-extras install docker
sudo service docker start

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#!/bin/bash
# Sometimes you need to move your existing git repository
# to a new remote repository (/new remote origin).
# Here are a simple and quick steps that does exactly this.
#
# Let's assume we call "old repo" the repository you wish
# to move, and "new repo" the one you wish to move to.
#
### Step 1. Make sure you have a local copy of all "old repo"
### branches and tags.