JDK 25 refresh: declare the Java version, build it, and prove it

.gitattributes

@@ -0,0 +1,19 @@
+# Normalise line endings. The repository was written on Windows in 2017 and most
+# sources are still CRLF, which shows up as whole-file diffs for anyone on Linux
+# or macOS. Text is stored LF in the repository and checked out native.
+* text=auto
+
+*.java   text diff=java
+*.md     text
+*.xml    text
+*.yml    text
+*.properties text
+
+*.classpath text
+*.project   text
+*.iml       text
+
+*.png binary
+*.jpg binary
+*.gif binary
+*.jar binary

.github/workflows/build.yml

@@ -0,0 +1,33 @@
+# Builds every example on the Java release named in pom.xml, on all three
+# desktop operating systems a student might be using. Its job is to notice when
+# a future JDK stops accepting this code, rather than leaving it to be found
+# years later.
+name: build
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+  workflow_dispatch:
+  schedule:
+    - cron: "0 6 1 * *"   # monthly, so bit-rot surfaces without a push
+
+jobs:
+  build:
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ ubuntu-latest, windows-latest, macos-latest ]
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up JDK 25
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: '25'
+          cache: maven
+
+      - name: Build
+        run: mvn -B --no-transfer-progress clean compile

.gitignore

@@ -50,4 +50,9 @@ local.properties
 # Scala IDE specific (Scala & Java development for Eclipse)
 .cache-main
 .scala_dependencies
-.worksheet
+.worksheet
+# Maven
+target/
+
+# IntelliJ per-user state (layout, open tabs, local paths)
+.idea/workspace.xml

ConsoleApps/pom.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<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>
+
+  <parent>
+    <groupId>beam.example</groupId>
+    <artifactId>java-app-examples</artifactId>
+    <version>1.2.0</version>
+  </parent>
+
+  <artifactId>console-apps</artifactId>
+  <name>Console Examples</name>
+
+  <!-- The sources stay where they have always been: src/, not src/main/java. -->
+  <build>
+    <sourceDirectory>src</sourceDirectory>
+  </build>
+
+</project>