8209003: Consolidate use of empty collections in java.lang.module
Reviewed-by: alanb, mchung
--- a/src/java.base/share/classes/java/lang/Module.java Tue Aug 07 13:51:30 2018 -0700
+++ b/src/java.base/share/classes/java/lang/Module.java Tue Aug 07 23:08:52 2018 +0200
@@ -40,7 +40,6 @@
import java.net.URL;
import java.security.AccessController;
import java.security.PrivilegedAction;
-import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
@@ -1123,7 +1122,7 @@
Set<Module> reads = new HashSet<>();
// name -> source Module when in parent layer
- Map<String, Module> nameToSource = Collections.emptyMap();
+ Map<String, Module> nameToSource = Map.of();
for (ResolvedModule other : resolvedModule.reads()) {
Module m2 = null;
--- a/src/java.base/share/classes/java/lang/ModuleLayer.java Tue Aug 07 13:51:30 2018 -0700
+++ b/src/java.base/share/classes/java/lang/ModuleLayer.java Tue Aug 07 23:08:52 2018 +0200
@@ -173,7 +173,7 @@
Map<String, Module> map;
if (parents.isEmpty()) {
- map = Collections.emptyMap();
+ map = Map.of();
} else {
map = Module.defineModules(cf, clf, this);
}
@@ -811,8 +811,7 @@
public Set<Module> modules() {
Set<Module> modules = this.modules;
if (modules == null) {
- this.modules = modules =
- Collections.unmodifiableSet(new HashSet<>(nameToModule.values()));
+ this.modules = modules = Set.copyOf(nameToModule.values());
}
return modules;
}
--- a/src/java.base/share/classes/java/lang/module/Configuration.java Tue Aug 07 13:51:30 2018 -0700
+++ b/src/java.base/share/classes/java/lang/module/Configuration.java Tue Aug 07 23:08:52 2018 +0200
@@ -31,7 +31,6 @@
import java.util.Collection;
import java.util.Collections;
import java.util.Deque;
-import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
@@ -119,10 +118,10 @@
String targetPlatform() { return targetPlatform; }
private Configuration() {
- this.parents = Collections.emptyList();
- this.graph = Collections.emptyMap();
- this.modules = Collections.emptySet();
- this.nameToModule = Collections.emptyMap();
+ this.parents = List.of();
+ this.graph = Map.of();
+ this.modules = Set.of();
+ this.nameToModule = Map.of();
this.targetPlatform = null;
}
@@ -140,7 +139,7 @@
i++;
}
- this.parents = Collections.unmodifiableList(parents);
+ this.parents = List.copyOf(parents);
this.graph = g;
this.modules = Set.of(moduleArray);
this.nameToModule = Map.ofEntries(nameEntries);
@@ -554,7 +553,7 @@
Set<ModuleDescriptor> descriptors() {
if (modules.isEmpty()) {
- return Collections.emptySet();
+ return Set.of();
} else {
return modules.stream()
.map(ResolvedModule::reference)
@@ -596,7 +595,7 @@
}
}
}
- this.allConfigurations = Collections.unmodifiableList(allConfigurations);
+ this.allConfigurations = allConfigurations; // no need to do defensive copy
}
return allConfigurations.stream();
}
--- a/src/java.base/share/classes/java/lang/module/ModuleDescriptor.java Tue Aug 07 13:51:30 2018 -0700
+++ b/src/java.base/share/classes/java/lang/module/ModuleDescriptor.java Tue Aug 07 23:08:52 2018 +0200
@@ -102,7 +102,7 @@
* @since 9
* @spec JPMS
*/
- public static enum Modifier {
+ public enum Modifier {
/**
* An open module. An open module does not declare any open packages
* but the resulting module is treated as if all packages are open.
@@ -149,7 +149,7 @@
* @since 9
* @spec JPMS
*/
- public static enum Modifier {
+ public enum Modifier {
/**
* The dependence causes any module which depends on the <i>current
@@ -185,12 +185,7 @@
private Requires(Set<Modifier> ms, String mn, Version v, String vs) {
assert v == null || vs == null;
- if (ms.isEmpty()) {
- ms = Collections.emptySet();
- } else {
- ms = Collections.unmodifiableSet(EnumSet.copyOf(ms));
- }
- this.mods = ms;
+ this.mods = Set.copyOf(ms);
this.name = mn;
this.compiledVersion = v;
this.rawCompiledVersion = vs;
@@ -384,7 +379,7 @@
* @since 9
* @spec JPMS
*/
- public static enum Modifier {
+ public enum Modifier {
/**
* The export was not explicitly or implicitly declared in the
@@ -408,14 +403,9 @@
* Constructs an export
*/
private Exports(Set<Modifier> ms, String source, Set<String> targets) {
- if (ms.isEmpty()) {
- ms = Collections.emptySet();
- } else {
- ms = Collections.unmodifiableSet(EnumSet.copyOf(ms));
- }
- this.mods = ms;
+ this.mods = Set.copyOf(ms);
this.source = source;
- this.targets = emptyOrUnmodifiableSet(targets);
+ this.targets = Set.copyOf(targets);
}
private Exports(Set<Modifier> ms,
@@ -596,7 +586,7 @@
* @since 9
* @spec JPMS
*/
- public static enum Modifier {
+ public enum Modifier {
/**
* The open package was not explicitly or implicitly declared in
@@ -620,14 +610,9 @@
* Constructs an Opens
*/
private Opens(Set<Modifier> ms, String source, Set<String> targets) {
- if (ms.isEmpty()) {
- ms = Collections.emptySet();
- } else {
- ms = Collections.unmodifiableSet(EnumSet.copyOf(ms));
- }
- this.mods = ms;
+ this.mods = Set.copyOf(ms);
this.source = source;
- this.targets = emptyOrUnmodifiableSet(targets);
+ this.targets = Set.copyOf(targets);
}
private Opens(Set<Modifier> ms,
@@ -800,7 +785,7 @@
private Provides(String service, List<String> providers) {
this.service = service;
- this.providers = Collections.unmodifiableList(providers);
+ this.providers = List.copyOf(providers);
}
private Provides(String service, List<String> providers, boolean unused) {
@@ -1264,18 +1249,18 @@
this.name = name;
this.version = version;
this.rawVersionString = rawVersionString;
- this.modifiers = emptyOrUnmodifiableSet(modifiers);
+ this.modifiers = Set.copyOf(modifiers);
this.open = modifiers.contains(Modifier.OPEN);
this.automatic = modifiers.contains(Modifier.AUTOMATIC);
assert (requires.stream().map(Requires::name).distinct().count()
== requires.size());
- this.requires = emptyOrUnmodifiableSet(requires);
- this.exports = emptyOrUnmodifiableSet(exports);
- this.opens = emptyOrUnmodifiableSet(opens);
- this.uses = emptyOrUnmodifiableSet(uses);
- this.provides = emptyOrUnmodifiableSet(provides);
+ this.requires = Set.copyOf(requires);
+ this.exports = Set.copyOf(exports);
+ this.opens = Set.copyOf(opens);
+ this.uses = Set.copyOf(uses);
+ this.provides = Set.copyOf(provides);
- this.packages = emptyOrUnmodifiableSet(packages);
+ this.packages = Set.copyOf(packages);
this.mainClass = mainClass;
}
@@ -1734,16 +1719,14 @@
String pn,
Set<String> targets)
{
- Exports e = new Exports(ms, pn, targets);
-
- // check targets
- targets = e.targets();
+ targets = new HashSet<>(targets);
if (targets.isEmpty())
throw new IllegalArgumentException("Empty target set");
if (strict) {
- requirePackageName(e.source());
+ requirePackageName(pn);
targets.forEach(Checks::requireModuleName);
}
+ Exports e = new Exports(ms, pn, targets);
return exports(e);
}
@@ -1769,7 +1752,7 @@
if (strict) {
requirePackageName(pn);
}
- Exports e = new Exports(ms, pn, Collections.emptySet());
+ Exports e = new Exports(ms, pn, Set.of());
return exports(e);
}
@@ -1794,7 +1777,7 @@
* or this builder is for an automatic module
*/
public Builder exports(String pn, Set<String> targets) {
- return exports(Collections.emptySet(), pn, targets);
+ return exports(Set.of(), pn, targets);
}
/**
@@ -1813,7 +1796,7 @@
* or this builder is for an automatic module
*/
public Builder exports(String pn) {
- return exports(Collections.emptySet(), pn);
+ return exports(Set.of(), pn);
}
/**
@@ -1870,16 +1853,14 @@
String pn,
Set<String> targets)
{
- Opens opens = new Opens(ms, pn, targets);
-
- // check targets
- targets = opens.targets();
+ targets = new HashSet<>(targets);
if (targets.isEmpty())
throw new IllegalArgumentException("Empty target set");
if (strict) {
- requirePackageName(opens.source());
+ requirePackageName(pn);
targets.forEach(Checks::requireModuleName);
}
+ Opens opens = new Opens(ms, pn, targets);
return opens(opens);
}
@@ -1905,7 +1886,7 @@
if (strict) {
requirePackageName(pn);
}
- Opens e = new Opens(ms, pn, Collections.emptySet());
+ Opens e = new Opens(ms, pn, Set.of());
return opens(e);
}
@@ -1929,7 +1910,7 @@
* builder for an open module or automatic module
*/
public Builder opens(String pn, Set<String> targets) {
- return opens(Collections.emptySet(), pn, targets);
+ return opens(Set.of(), pn, targets);
}
/**
@@ -1948,7 +1929,7 @@
* builder for an open module or automatic module
*/
public Builder opens(String pn) {
- return opens(Collections.emptySet(), pn);
+ return opens(Set.of(), pn);
}
/**
@@ -2021,15 +2002,12 @@
* declared
*/
public Builder provides(String service, List<String> providers) {
- Provides p = new Provides(service, providers);
-
- // check providers after the set has been copied.
- List<String> providerNames = p.providers();
- if (providerNames.isEmpty())
+ providers = new ArrayList<>(providers);
+ if (providers.isEmpty())
throw new IllegalArgumentException("Empty providers set");
if (strict) {
- requireServiceTypeName(p.service());
- providerNames.forEach(Checks::requireServiceProviderName);
+ requireServiceTypeName(service);
+ providers.forEach(Checks::requireServiceProviderName);
} else {
// Disallow service/providers in unnamed package
String pn = packageName(service);
@@ -2037,7 +2015,7 @@
throw new IllegalArgumentException(service
+ ": unnamed package");
}
- for (String name : providerNames) {
+ for (String name : providers) {
pn = packageName(name);
if (pn.isEmpty()) {
throw new IllegalArgumentException(name
@@ -2045,6 +2023,7 @@
}
}
}
+ Provides p = new Provides(service, providers);
return provides(p);
}
@@ -2574,27 +2553,6 @@
return ModuleInfo.read(bb, null).descriptor();
}
- private static <K,V> Map<K,V> emptyOrUnmodifiableMap(Map<K,V> map) {
- if (map.isEmpty()) {
- return Collections.emptyMap();
- } else if (map.size() == 1) {
- Map.Entry<K, V> entry = map.entrySet().iterator().next();
- return Collections.singletonMap(entry.getKey(), entry.getValue());
- } else {
- return Collections.unmodifiableMap(map);
- }
- }
-
- private static <T> Set<T> emptyOrUnmodifiableSet(Set<T> set) {
- if (set.isEmpty()) {
- return Collections.emptySet();
- } else if (set.size() == 1) {
- return Collections.singleton(set.iterator().next());
- } else {
- return Collections.unmodifiableSet(set);
- }
- }
-
private static String packageName(String cn) {
int index = cn.lastIndexOf('.');
return (index == -1) ? "" : cn.substring(0, index);
@@ -2674,7 +2632,7 @@
@Override
public Exports newExports(Set<Exports.Modifier> ms, String source) {
- return new Exports(ms, source, Collections.emptySet(), true);
+ return new Exports(ms, source, Set.of(), true);
}
@Override
@@ -2693,7 +2651,7 @@
@Override
public Opens newOpens(Set<Opens.Modifier> ms, String source) {
- return new Opens(ms, source, Collections.emptySet(), true);
+ return new Opens(ms, source, Set.of(), true);
}
@Override
--- a/src/java.base/share/classes/java/lang/module/ModuleFinder.java Tue Aug 07 13:51:30 2018 -0700
+++ b/src/java.base/share/classes/java/lang/module/ModuleFinder.java Tue Aug 07 23:08:52 2018 +0200
@@ -306,7 +306,7 @@
@Override
public Set<ModuleReference> findAll() {
- return Collections.emptySet();
+ return Set.of();
}
};
}
--- a/src/java.base/share/classes/jdk/internal/module/Builder.java Tue Aug 07 13:51:30 2018 -0700
+++ b/src/java.base/share/classes/jdk/internal/module/Builder.java Tue Aug 07 23:08:52 2018 +0200
@@ -30,7 +30,6 @@
import java.lang.module.ModuleDescriptor.Provides;
import java.lang.module.ModuleDescriptor.Requires;
import java.lang.module.ModuleDescriptor.Version;
-import java.util.Collections;
import java.util.List;
import java.util.Set;
@@ -148,11 +147,11 @@
Builder(String name) {
this.name = name;
- this.requires = Collections.emptySet();
- this.exports = Collections.emptySet();
- this.opens = Collections.emptySet();
- this.provides = Collections.emptySet();
- this.uses = Collections.emptySet();
+ this.requires = Set.of();
+ this.exports = Set.of();
+ this.opens = Set.of();
+ this.provides = Set.of();
+ this.uses = Set.of();
}
Builder open(boolean value) {
@@ -253,7 +252,7 @@
if (synthetic) n++;
if (mandated) n++;
if (n == 0) {
- return Collections.emptySet();
+ return Set.of();
} else {
ModuleDescriptor.Modifier[] mods = new ModuleDescriptor.Modifier[n];
if (open) mods[--n] = ModuleDescriptor.Modifier.OPEN;
--- a/src/java.base/share/classes/jdk/internal/module/ExplodedSystemModules.java Tue Aug 07 13:51:30 2018 -0700
+++ b/src/java.base/share/classes/jdk/internal/module/ExplodedSystemModules.java Tue Aug 07 23:08:52 2018 +0200
@@ -26,7 +26,6 @@
package jdk.internal.module;
import java.lang.module.ModuleDescriptor;
-import java.util.Collections;
import java.util.Map;
import java.util.Set;
@@ -72,11 +71,11 @@
@Override
public Map<String, Set<String>> concealedPackagesToOpen() {
- return Collections.emptyMap();
+ return Map.of();
}
@Override
public Map<String, Set<String>> exportedPackagesToOpen() {
- return Collections.emptyMap();
+ return Map.of();
}
}
--- a/src/java.base/share/classes/jdk/internal/module/ModuleBootstrap.java Tue Aug 07 13:51:30 2018 -0700
+++ b/src/java.base/share/classes/jdk/internal/module/ModuleBootstrap.java Tue Aug 07 23:08:52 2018 +0200
@@ -568,7 +568,7 @@
// the system property is removed after decoding
String value = getAndRemoveProperty(prefix + index);
if (value == null) {
- return Collections.emptySet();
+ return Set.of();
} else {
Set<String> modules = new HashSet<>();
while (value != null) {
@@ -588,7 +588,7 @@
private static Set<String> limitModules() {
String value = getAndRemoveProperty("jdk.module.limitmods");
if (value == null) {
- return Collections.emptySet();
+ return Set.of();
} else {
Set<String> names = new HashSet<>();
for (String name : value.split(",")) {
@@ -840,7 +840,7 @@
// the system property is removed after decoding
String value = getAndRemoveProperty(prefix + index);
if (value == null)
- return Collections.emptyMap();
+ return Map.of();
Map<String, List<String>> map = new HashMap<>();
--- a/src/java.base/share/classes/jdk/internal/module/ModuleInfo.java Tue Aug 07 13:51:30 2018 -0700
+++ b/src/java.base/share/classes/jdk/internal/module/ModuleInfo.java Tue Aug 07 23:08:52 2018 +0200
@@ -40,7 +40,6 @@
import java.nio.ByteBuffer;
import java.nio.BufferUnderflowException;
import java.util.ArrayList;
-import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
@@ -374,7 +373,7 @@
int requires_flags = in.readUnsignedShort();
Set<Requires.Modifier> mods;
if (requires_flags == 0) {
- mods = Collections.emptySet();
+ mods = Set.of();
} else {
mods = new HashSet<>();
if ((requires_flags & ACC_TRANSITIVE) != 0)
@@ -430,7 +429,7 @@
Set<Exports.Modifier> mods;
int exports_flags = in.readUnsignedShort();
if (exports_flags == 0) {
- mods = Collections.emptySet();
+ mods = Set.of();
} else {
mods = new HashSet<>();
if ((exports_flags & ACC_SYNTHETIC) != 0)
@@ -470,7 +469,7 @@
Set<Opens.Modifier> mods;
int opens_flags = in.readUnsignedShort();
if (opens_flags == 0) {
- mods = Collections.emptySet();
+ mods = Set.of();
} else {
mods = new HashSet<>();
if ((opens_flags & ACC_SYNTHETIC) != 0)
--- a/src/java.base/share/classes/jdk/internal/module/ModulePatcher.java Tue Aug 07 13:51:30 2018 -0700
+++ b/src/java.base/share/classes/jdk/internal/module/ModulePatcher.java Tue Aug 07 23:08:52 2018 +0200
@@ -42,7 +42,6 @@
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayList;
-import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
@@ -78,7 +77,7 @@
*/
public ModulePatcher(Map<String, List<String>> input) {
if (input.isEmpty()) {
- this.map = Collections.emptyMap();
+ this.map = Map.of();
} else {
Map<String, List<Path>> map = new HashMap<>();
for (Map.Entry<String, List<String>> e : input.entrySet()) {
--- a/src/java.base/share/classes/jdk/internal/module/ModulePath.java Tue Aug 07 13:51:30 2018 -0700
+++ b/src/java.base/share/classes/jdk/internal/module/ModulePath.java Tue Aug 07 23:08:52 2018 +0200
@@ -45,7 +45,6 @@
import java.nio.file.Path;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.ArrayList;
-import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
@@ -217,7 +216,7 @@
try {
attrs = Files.readAttributes(entry, BasicFileAttributes.class);
} catch (NoSuchFileException e) {
- return Collections.emptyMap();
+ return Map.of();
} catch (IOException ioe) {
throw new FindException(ioe);
}
@@ -236,7 +235,7 @@
ModuleReference mref = readModule(entry, attrs);
if (mref != null) {
String name = mref.descriptor().name();
- return Collections.singletonMap(name, mref);
+ return Map.of(name, mref);
}
// not recognized
--- a/src/java.base/share/classes/jdk/internal/module/ServicesCatalog.java Tue Aug 07 13:51:30 2018 -0700
+++ b/src/java.base/share/classes/jdk/internal/module/ServicesCatalog.java Tue Aug 07 23:08:52 2018 +0200
@@ -28,7 +28,6 @@
import java.lang.module.ModuleDescriptor;
import java.lang.module.ModuleDescriptor.Provides;
import java.util.ArrayList;
-import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Objects;
@@ -147,7 +146,7 @@
* the given service type.
*/
public List<ServiceProvider> findServices(String service) {
- return map.getOrDefault(service, Collections.emptyList());
+ return map.getOrDefault(service, List.of());
}
/**
@@ -175,4 +174,4 @@
// the ServicesCatalog registered to a class loader
private static final ClassLoaderValue<ServicesCatalog> CLV = new ClassLoaderValue<>();
-}
\ No newline at end of file
+}
--- a/src/java.base/share/classes/jdk/internal/module/SystemModuleFinders.java Tue Aug 07 13:51:30 2018 -0700
+++ b/src/java.base/share/classes/jdk/internal/module/SystemModuleFinders.java Tue Aug 07 23:08:52 2018 +0200
@@ -282,8 +282,8 @@
SystemModuleFinder(Set<ModuleReference> mrefs,
Map<String, ModuleReference> nameToModule) {
- this.mrefs = Collections.unmodifiableSet(mrefs);
- this.nameToModule = Collections.unmodifiableMap(nameToModule);
+ this.mrefs = Set.copyOf(mrefs);
+ this.nameToModule = Map.copyOf(nameToModule);
}
@Override
@@ -353,7 +353,7 @@
}
}
}
- return (nameToHash != null) ? nameToHash : Collections.emptyMap();
+ return (nameToHash != null) ? nameToHash : Map.of();
}
/**
--- a/test/jdk/java/lang/module/ModuleDescriptorTest.java Tue Aug 07 13:51:30 2018 -0700
+++ b/test/jdk/java/lang/module/ModuleDescriptorTest.java Tue Aug 07 23:08:52 2018 +0200
@@ -147,7 +147,12 @@
public void testRequiresWithRequires() {
Requires r1 = requires("foo");
ModuleDescriptor descriptor = ModuleDescriptor.newModule("m").requires(r1).build();
- Requires r2 = descriptor.requires().iterator().next();
+ assertEquals(descriptor.requires().size(), 2);
+ var iterator = descriptor.requires().iterator();
+ Requires r2 = iterator.next();
+ if (r2.name().equals("java.base")) {
+ r2 = iterator.next();
+ }
assertEquals(r1, r2);
}