GitHub Action: Build project with Gradle

.github/workflows/ci.yml

@@ -0,0 +1,14 @@
+name: CI
+on: [push]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up JDK 8
+        uses: actions/setup-java@v2
+        with:
+          java-version: 8
+          distribution: 'adopt'
+      - name: Build with Gradle
+        run: ./gradlew build

README.md

@@ -1,3 +1,4 @@
+[![CI](https://github.com/Borewit/listFix/actions/workflows/ci.yml/badge.svg)](https://github.com/Borewit/listFix/actions/workflows/ci.yml)
 
 # listFix() - Playlist Repair Done Right
 Have you ever spent some time making a playlist, only to have it break when you reorganize your files? listFix() is a Swing application that solves this problem by finding the lost or missing entries in your playlists automatically.  Tell it where you keep your media files, load in the playlist you want to fix, and hit the locate button.  The program will search your media library for the file and update the playlist accordingly when it finds a match.