ZOOKEEPER-2630: Use interface type instead of implementation type whe…

Use interface type instead of implementation type when appropriate. There are a couple of places in code base where we declare a field / variable as implementation type (i.e. HashMap, HashSet) instead of interface type (i.e. Map, Set), while in other places we do the opposite by declaring as interface type. A quick check indicates that most if not all of these places could be updated so we have a consistent style over the code base (prefer using interface type), which is also a good coding style to stick per best practice. Checked and fixed Set, Map and List interface usages. Author: Tamas Penzes <[email protected]> Reviewers: Abe Fine <[email protected]>, Michael Han <[email protected]> Closes apache#354 from tamaashu/ZOOKEEPER-2630
neo4reo · Sep 11, 2017 · 1165794 · 1165794
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diff --git a/docs/zookeeperReconfig.html b/docs/zookeeperReconfig.html
@@ -1011,7 +1011,7 @@ <h4>Non-incremental mode</h4>
           example, you may specify a Hierarchical Quorum System even if the
           current ensemble uses a Majority Quorum System.</p>
 <p>Bulk mode - example using the Java API:</p>
-<pre class="code">ArrayList&lt;String&gt; newMembers = new ArrayList&lt;String&gt;();
+<pre class="code">List&lt;String&gt; newMembers = new ArrayList&lt;String&gt;();
 newMembers.add("server.1=1111:1234:1235;1236");
 newMembers.add("server.2=1112:1237:1238;1239");
 newMembers.add("server.3=1114:1240:1241:observer;1242");

diff --git a/src/contrib/fatjar/src/java/org/apache/zookeeper/util/FatJarMain.java b/src/contrib/fatjar/src/java/org/apache/zookeeper/util/FatJarMain.java
@@ -26,6 +26,8 @@
 import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
 
 /**
  * This is a generic Main class that is completely driven by the
@@ -48,8 +50,8 @@ static class Cmd {
         String clazz;
         String desc;
     }
-    static HashMap<String, Cmd> cmds = new HashMap<String, Cmd>();
-    static ArrayList<String> order = new ArrayList<String>();
+    static Map<String, Cmd> cmds = new HashMap<String, Cmd>();
+    static List<String> order = new ArrayList<String>();
 
     /**
      * @param args the first parameter of args will be used as an

diff --git a/src/contrib/loggraph/src/java/org/apache/zookeeper/graph/FilterOp.java b/src/contrib/loggraph/src/java/org/apache/zookeeper/graph/FilterOp.java
@@ -18,11 +18,12 @@
 package org.apache.zookeeper.graph;
 
 import java.util.ArrayList;
+import java.util.List;
 import org.apache.zookeeper.graph.filterops.*;
 
 public abstract class FilterOp {
-    protected ArrayList<FilterOp> subOps;
-    protected ArrayList<Arg> args;
+    protected List<FilterOp> subOps;
+    protected List<Arg> args;
 
     public enum ArgType {
 	STRING, NUMBER, SYMBOL

diff --git a/src/contrib/loggraph/src/java/org/apache/zookeeper/graph/JsonGenerator.java b/src/contrib/loggraph/src/java/org/apache/zookeeper/graph/JsonGenerator.java
@@ -31,10 +31,11 @@
 import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.ListIterator;
+import java.util.Set;
 
 public class JsonGenerator {
     private JSONObject root;
-    private HashSet<Integer> servers;
+    private Set<Integer> servers;
 
     private class Message {
 	private int from;

diff --git a/src/contrib/loggraph/src/java/org/apache/zookeeper/graph/LogEntry.java b/src/contrib/loggraph/src/java/org/apache/zookeeper/graph/LogEntry.java
@@ -19,9 +19,10 @@
 
 import java.io.Serializable;
 import java.util.HashMap;
+import java.util.Map;
 
 public abstract class LogEntry implements Serializable {
-    private HashMap attributes;
+    private Map attributes;
 
     public enum Type { UNKNOWN, LOG4J, TXN };
 

diff --git a/src/contrib/loggraph/src/java/org/apache/zookeeper/graph/MeasureThroughput.java b/src/contrib/loggraph/src/java/org/apache/zookeeper/graph/MeasureThroughput.java
@@ -24,6 +24,7 @@
 import java.io.PrintStream;
 
 import java.util.HashSet;
+import java.util.Set;
 
 public class MeasureThroughput {
     private static final int MS_PER_SEC = 1000;
@@ -45,7 +46,7 @@ public static void main(String[] args) throws IOException {
 	long currentsec = 0;
 	long currentmin = 0;
 	long currenthour = 0;
-	HashSet<Long> zxids_ms = new HashSet<Long>();
+	Set<Long> zxids_ms = new HashSet<Long>();
 	long zxid_sec = 0;
 	long zxid_min = 0;
 	long zxid_hour = 0;

diff --git a/src/contrib/loggraph/src/java/org/apache/zookeeper/graph/servlets/Throughput.java b/src/contrib/loggraph/src/java/org/apache/zookeeper/graph/servlets/Throughput.java
@@ -25,6 +25,7 @@
 
 import java.util.HashSet;
 import java.util.LinkedHashMap;
+import java.util.Set;
 
 import org.apache.zookeeper.graph.*;
 import org.slf4j.Logger;
@@ -80,7 +81,7 @@ public String handleRequest(JsonRequest request) throws Exception {
 
 	long current = 0;
 	long currentms = 0;
-	HashSet<Long> zxids_ms = new HashSet<Long>();
+	Set<Long> zxids_ms = new HashSet<Long>();
 	long zxidcount = 0;
 
 	JSONArray events = new JSONArray();

diff --git a/...r/src/java/org/apache/zookeeper/inspector/gui/ZooInspectorConnectionPropertiesDialog.java b/...r/src/java/org/apache/zookeeper/inspector/gui/ZooInspectorConnectionPropertiesDialog.java
@@ -51,7 +51,7 @@
  */
 public class ZooInspectorConnectionPropertiesDialog extends JDialog {
 
-    private final HashMap<String, JComponent> components;
+    private final Map<String, JComponent> components;
 
     /**
      * @param lastConnectionProps

diff --git a/src/contrib/zooinspector/src/java/org/apache/zookeeper/inspector/gui/ZooInspectorPanel.java b/src/contrib/zooinspector/src/java/org/apache/zookeeper/inspector/gui/ZooInspectorPanel.java
@@ -64,7 +64,7 @@ public ZooInspectorPanel(final ZooInspectorManager zooInspectorManager, final Ic
         this.zooInspectorManager = zooInspectorManager;
         this.iconResource = iconResource;
         toolbar = new Toolbar(iconResource);
-        final ArrayList<ZooInspectorNodeViewer> nodeViewers = new ArrayList<ZooInspectorNodeViewer>();
+        final List<ZooInspectorNodeViewer> nodeViewers = new ArrayList<ZooInspectorNodeViewer>();
         try {
             List<String> defaultNodeViewersClassNames = this.zooInspectorManager
                     .getDefaultNodeViewerConfiguration();

diff --git a/src/docs/src/documentation/content/xdocs/zookeeperReconfig.xml b/src/docs/src/documentation/content/xdocs/zookeeperReconfig.xml
@@ -693,7 +693,7 @@ System.out.println(configStr);]]></programlisting>
           example, you may specify a Hierarchical Quorum System even if the
           current ensemble uses a Majority Quorum System.</para>
         <para>Bulk mode - example using the Java API:</para>
-        <programlisting><![CDATA[ArrayList<String> newMembers = new ArrayList<String>();
+        <programlisting><![CDATA[List<String> newMembers = new ArrayList<String>();
 newMembers.add("server.1=1111:1234:1235;1236");
 newMembers.add("server.2=1112:1237:1238;1239");
 newMembers.add("server.3=1114:1240:1241:observer;1242");

diff --git a/src/java/main/org/apache/jute/compiler/CGenerator.java b/src/java/main/org/apache/jute/compiler/CGenerator.java
@@ -18,19 +18,19 @@
 
 package org.apache.jute.compiler;
 
-import java.util.ArrayList;
 import java.io.File;
 import java.io.FileWriter;
 import java.io.IOException;
 import java.util.Iterator;
+import java.util.List;
 
 /**
  * C++ Code generator front-end for Hadoop record I/O.
  */
 class CGenerator {
     private String mName;
-    private ArrayList<JFile> mInclFiles;
-    private ArrayList<JRecord> mRecList;
+    private List<JFile> mInclFiles;
+    private List<JRecord> mRecList;
     private final File outputDirectory;
 
     /** Creates a new instance of CppGenerator
@@ -40,7 +40,7 @@ class CGenerator {
      * @param rlist List of records defined within this file
      * @param outputDirectory
      */
-    CGenerator(String name, ArrayList<JFile> ilist, ArrayList<JRecord> rlist,
+    CGenerator(String name, List<JFile> ilist, List<JRecord> rlist,
             File outputDirectory)
     {
         this.outputDirectory = outputDirectory;

diff --git a/src/java/main/org/apache/jute/compiler/CSharpGenerator.java b/src/java/main/org/apache/jute/compiler/CSharpGenerator.java
@@ -20,10 +20,10 @@
 
 import java.io.File;
 import java.io.IOException;
-import java.util.ArrayList;
+import java.util.List;
 
 public class CSharpGenerator {
-    private ArrayList<JRecord> mRecList;
+    private List<JRecord> mRecList;
     private final File outputDirectory;
 
     /** Creates a new instance of CSharpGenerator
@@ -33,7 +33,7 @@ public class CSharpGenerator {
      * @param rlist List of records defined within this file
      * @param outputDirectory
      */
-    CSharpGenerator(String name, ArrayList<JFile> ilist, ArrayList<JRecord> rlist,
+    CSharpGenerator(String name, List<JFile> ilist, List<JRecord> rlist,
             File outputDirectory)
      {
         this.outputDirectory = outputDirectory;

diff --git a/src/java/main/org/apache/jute/compiler/CppGenerator.java b/src/java/main/org/apache/jute/compiler/CppGenerator.java
@@ -18,19 +18,19 @@
 
 package org.apache.jute.compiler;
 
-import java.util.ArrayList;
 import java.io.File;
 import java.io.FileWriter;
 import java.io.IOException;
 import java.util.Iterator;
+import java.util.List;
 
 /**
  * C++ Code generator front-end for Hadoop record I/O.
  */
 class CppGenerator {
     private String mName;
-    private ArrayList<JFile> mInclFiles;
-    private ArrayList<JRecord> mRecList;
+    private List<JFile> mInclFiles;
+    private List<JRecord> mRecList;
     private final File outputDirectory;
 
     /** Creates a new instance of CppGenerator
@@ -40,7 +40,7 @@ class CppGenerator {
      * @param rlist List of records defined within this file
      * @param outputDirectory
      */
-    CppGenerator(String name, ArrayList<JFile> ilist, ArrayList<JRecord> rlist,
+    CppGenerator(String name, List<JFile> ilist, List<JRecord> rlist,
             File outputDirectory)
      {
         this.outputDirectory = outputDirectory;

diff --git a/src/java/main/org/apache/jute/compiler/JFile.java b/src/java/main/org/apache/jute/compiler/JFile.java
@@ -21,6 +21,7 @@
 import java.io.File;
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.List;
 
 /**
  * Container for the Hadoop Record DDL.
@@ -31,8 +32,8 @@
 public class JFile {
 
     private String mName;
-    private ArrayList<JFile> mInclFiles;
-    private ArrayList<JRecord> mRecords;
+    private List<JFile> mInclFiles;
+    private List<JRecord> mRecords;
 
     /** Creates a new instance of JFile
      *

diff --git a/src/java/main/org/apache/jute/compiler/JRecord.java b/src/java/main/org/apache/jute/compiler/JRecord.java
@@ -24,6 +24,8 @@
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
 
 /**
  *
@@ -33,7 +35,7 @@ public class JRecord extends JCompType {
     private String mFQName;
     private String mName;
     private String mModule;
-    private ArrayList<JField> mFields;
+    private List<JField> mFields;
 
     /**
      * Creates a new instance of JRecord
@@ -83,7 +85,7 @@ public String getCsharpNameSpace() {
         return namespace.toString();
     }
 
-    public ArrayList<JField> getFields() {
+    public List<JField> getFields() {
         return mFields;
     }
 
@@ -139,7 +141,7 @@ public String genCsharpWriteWrapper(String fname, String tag) {
         return "    a_.WriteRecord("+fname+",\""+tag+"\");\n";
     }
 
-    static HashMap<String, String> vectorStructs = new HashMap<String, String>();
+    static Map<String, String> vectorStructs = new HashMap<String, String>();
     public void genCCode(FileWriter h, FileWriter c) throws IOException {
         for (JField f : mFields) {
             if (f.getType() instanceof JVector) {

diff --git a/src/java/main/org/apache/jute/compiler/JavaGenerator.java b/src/java/main/org/apache/jute/compiler/JavaGenerator.java
@@ -20,14 +20,14 @@
 
 import java.io.File;
 import java.io.IOException;
-import java.util.ArrayList;
 import java.util.Iterator;
+import java.util.List;
 
 /**
  * Java Code generator front-end for Hadoop record I/O.
  */
 class JavaGenerator {
-    private ArrayList<JRecord> mRecList;
+    private List<JRecord> mRecList;
     private final File outputDirectory;
 
     /** Creates a new instance of JavaGenerator
@@ -37,8 +37,8 @@ class JavaGenerator {
      * @param records List of records defined within this file
      * @param outputDirectory 
      */
-    JavaGenerator(String name, ArrayList<JFile> incl,
-            ArrayList<JRecord> records, File outputDirectory)
+    JavaGenerator(String name, List<JFile> incl,
+            List<JRecord> records, File outputDirectory)
     {
         mRecList = records;
         this.outputDirectory = outputDirectory;

diff --git a/src/java/main/org/apache/zookeeper/Environment.java b/src/java/main/org/apache/zookeeper/Environment.java
@@ -48,12 +48,12 @@ public String toString() {
         }
     }
 
-    private static void put(ArrayList<Entry> l, String k, String v) {
+    private static void put(List<Entry> l, String k, String v) {
         l.add(new Entry(k,v));
     }
 
     public static List<Entry> list() {
-        ArrayList<Entry> l = new ArrayList<Entry>();
+        List<Entry> l = new ArrayList<Entry>();
         put(l, "zookeeper.version", Version.getFullVersion());
 
         try {

diff --git a/src/java/main/org/apache/zookeeper/common/PathTrie.java b/src/java/main/org/apache/zookeeper/common/PathTrie.java
@@ -21,6 +21,7 @@
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -53,7 +54,7 @@ public class PathTrie {
 
     static class TrieNode {
         boolean property = false;
-        final HashMap<String, TrieNode> children;
+        final Map<String, TrieNode> children;
         TrieNode parent = null;
         /**
          * create a trienode with parent

diff --git a/src/java/main/org/apache/zookeeper/server/DataTree.java b/src/java/main/org/apache/zookeeper/server/DataTree.java
@@ -150,7 +150,7 @@ public Set<String> getEphemerals(long sessionId) {
         if (retv == null) {
             return new HashSet<String>();
         }
-        HashSet<String> cloned = null;
+        Set<String> cloned = null;
         synchronized (retv) {
             cloned = (HashSet<String>) retv.clone();
         }
@@ -549,7 +549,7 @@ public void deleteNode(String path, long zxid)
             } else if (ephemeralType == EphemeralType.TTL) {
                 ttls.remove(path);
             } else if (eowner != 0) {
-                HashSet<String> nodes = ephemerals.get(eowner);
+                Set<String> nodes = ephemerals.get(eowner);
                 if (nodes != null) {
                     synchronized (nodes) {
                         nodes.remove(path);
@@ -1002,7 +1002,7 @@ void killSession(long session, long zxid) {
         // so there is no need for synchronization. The list is not
         // changed here. Only create and delete change the list which
         // are again called from FinalRequestProcessor in sequence.
-        HashSet<String> list = ephemerals.remove(session);
+        Set<String> list = ephemerals.remove(session);
         if (list != null) {
             for (String path : list) {
                 try {
@@ -1286,7 +1286,7 @@ public void dumpEphemerals(PrintWriter pwriter) {
         for (Entry<Long, HashSet<String>> entry : ephemerals.entrySet()) {
             pwriter.print("0x" + Long.toHexString(entry.getKey()));
             pwriter.println(":");
-            HashSet<String> tmp = entry.getValue();
+            Set<String> tmp = entry.getValue();
             if (tmp != null) {
                 synchronized (tmp) {
                     for (String path : tmp) {
@@ -1303,7 +1303,7 @@ public void dumpEphemerals(PrintWriter pwriter) {
      * @return map of session ID to sets of ephemeral znodes
      */
     public Map<Long, Set<String>> getEphemerals() {
-        HashMap<Long, Set<String>> ephemeralsCopy = new HashMap<Long, Set<String>>();
+        Map<Long, Set<String>> ephemeralsCopy = new HashMap<Long, Set<String>>();
         for (Entry<Long, HashSet<String>> e : ephemerals.entrySet()) {
             synchronized (e.getValue()) {
                 ephemeralsCopy.put(e.getKey(), new HashSet<String>(e.getValue()));

diff --git a/src/java/main/org/apache/zookeeper/server/NettyServerCnxnFactory.java b/src/java/main/org/apache/zookeeper/server/NettyServerCnxnFactory.java
@@ -74,7 +74,7 @@ public class NettyServerCnxnFactory extends ServerCnxnFactory {
     ServerBootstrap bootstrap;
     Channel parentChannel;
     ChannelGroup allChannels = new DefaultChannelGroup("zkServerCnxns");
-    HashMap<InetAddress, Set<NettyServerCnxn>> ipMap =
+    Map<InetAddress, Set<NettyServerCnxn>> ipMap =
         new HashMap<InetAddress, Set<NettyServerCnxn>>( );
     InetSocketAddress localAddress;
     int maxClientCnxns = 60;
@@ -547,7 +547,7 @@ public void resetAllConnectionStats() {
 
     @Override
     public Iterable<Map<String, Object>> getAllConnectionInfo(boolean brief) {
-        HashSet<Map<String,Object>> info = new HashSet<Map<String,Object>>();
+        Set<Map<String,Object>> info = new HashSet<Map<String,Object>>();
         // No need to synchronize since cnxns is backed by a ConcurrentHashMap
         for (ServerCnxn c : cnxns) {
             info.add(c.getConnectionInfo(brief));