Simplify runtime version checks

build.gradle

@@ -33,33 +33,26 @@ repositories {
     mavenCentral()
 }
 
+
+def majorVersionToInt(majorVersionString) {
+    if (majorVersionString.endsWith("-ea")) {
+        majorVersionString = majorVersionString.substring(0, majorVersionString.length() - 3)
+    }
+    return Integer.valueOf(majorVersionString)
+}
+
 ext {
     release = false
 
     // On a Java 8 JVM, use error-prone javac and source/target 8.
     // On a Java 9+ JVM, use the host javac, default source/target, and required module flags.
     isJava8 = JavaVersion.current() == JavaVersion.VERSION_1_8
-    isJava14 = JavaVersion.current() == JavaVersion.VERSION_14
-    isJava15 = JavaVersion.current() == JavaVersion.VERSION_15
-    isJava16 = JavaVersion.current() == JavaVersion.VERSION_16
-    isJava17 = JavaVersion.current() == JavaVersion.VERSION_17
-    isJava18 = JavaVersion.current() == JavaVersion.VERSION_18
-    isJava19 = JavaVersion.current() == JavaVersion.VERSION_19
-    isJava20 = JavaVersion.current() == JavaVersion.VERSION_20
-    isJava21 = JavaVersion.current() == JavaVersion.VERSION_21
-
-    isJava21plus = isJava21
-    isJava20plus = isJava20 || isJava21plus
-    isJava19plus = isJava19 || isJava20plus
-    isJava18plus = isJava18 || isJava19plus
-    isJava17plus = isJava17 || isJava18plus
-    isJava16plus = isJava16 || isJava17plus
-    isJava15plus = isJava15 || isJava16plus
-    isJava14plus = isJava14 || isJava15plus
-    isJava11plus = JavaVersion.current() >= JavaVersion.VERSION_11
-
-    // As of 2023-09-23, delombok doesn't yet support JDK 22; see https://projectlombok.org/changelog .
-    skipDelombok = JavaVersion.current() > JavaVersion.VERSION_21
+
+    // The int corresponding to the major version of the current JVM.
+    currentRuntimeJavaVersion = majorVersionToInt(JavaVersion.current().getMajorVersion())
+
+    // As of 2024-08-06, delombok doesn't yet support JDK 23; see https://projectlombok.org/changelog .
+    skipDelombok = currentRuntimeJavaVersion >= 23
 
     parentDir = file("${rootDir}/../").absolutePath
 
@@ -122,7 +115,7 @@ task installGitHooks(type: Copy, dependsOn: 'setLocalRepo') {
     into localRepo + '/hooks'
 }
 
-if (isJava11plus) {
+if (currentRuntimeJavaVersion >= 11) {
     apply plugin: 'com.diffplug.spotless'
     spotless {
         // Resolve the Spotless plugin dependencies from the buildscript repositories rather than the
@@ -153,13 +146,6 @@ if (isJava11plus) {
     }
 }
 
-def majorVersionToInt(majorVersionString) {
-    if (majorVersionString.endsWith("-ea")) {
-        majorVersionString = majorVersionString.substring(0, majorVersionString.length() - 3)
-    }
-    return Integer.valueOf(majorVersionString)
-}
-
 allprojects {
     // Increment the minor version (second number) rather than just the patch
     // level (third number) if:
@@ -250,7 +236,7 @@ allprojects {
         ]
     }
 
-    if (isJava11plus) {
+    if (currentRuntimeJavaVersion >= 11) {
         apply plugin: 'com.diffplug.spotless'
         spotless {
             // If you add any formatters to this block that require dependencies, then you must also
@@ -266,20 +252,19 @@ allprojects {
                 '**/build/**',
                 '*/dist/**',
             ]
-            if (!isJava14plus) {
+            if (currentRuntimeJavaVersion < 14) {
                 doNotFormat += ['**/*record*/']
             }
-            if (!isJava16plus) {
+            if (currentRuntimeJavaVersion < 16) {
                 // TODO: directories should be renamed `-switchexpr` or some such,
                 // as they  only contain examples for switch expressions, which were
                 // added in Java 14, not Java 17.
                 doNotFormat += ['**/java17/']
             }
-            if (!isJava21plus) {
+            if (currentRuntimeJavaVersion < 21) {
                 doNotFormat += ['**/java21/']
             }
 
-
             format 'misc', {
                 // define the files to apply `misc` to
                 target '*.md', '*.tex', '.gitignore', 'Makefile'
@@ -395,14 +380,13 @@ allprojects {
         tasks.withType(JavaCompile) { compilationTask ->
             dependsOn(':installGitHooks')
             String useJdkCompilerProp = project.getProperties().get('useJdkCompiler')
-            int runtimeCompiler = majorVersionToInt(JavaVersion.current().getMajorVersion())
             int useJdkCompiler
             if (useJdkCompilerProp == null) {
                 // If the property is not given, use the same version as the runtime.
-                useJdkCompiler = runtimeCompiler
+                useJdkCompiler = currentRuntimeJavaVersion
             } else {
                 useJdkCompiler = majorVersionToInt(useJdkCompilerProp)
-                boolean useToolchains = (runtimeCompiler != useJdkCompiler)
+                boolean useToolchains = (currentRuntimeJavaVersion != useJdkCompiler)
                 if (!isJava8 && useToolchains) {
                     // This uses the requested Java compiler to compile all code.
                     // CI test test-cftests-junit-jdk21 runs the JUnit tests on the different JDK versions,