Core: Replace .size() > 0 with !.isEmpty() (#8813)

Core: Replace .size() > 0` with `!.isEmpty() (#8813)

core/src/main/java/org/apache/iceberg/BaseDistributedDataScan.java

@@ -146,7 +146,7 @@ protected CloseableIterable<ScanTask> doPlanFiles() {
     Snapshot snapshot = snapshot();
 
     List<ManifestFile> deleteManifests = findMatchingDeleteManifests(snapshot);
-    boolean mayHaveEqualityDeletes = deleteManifests.size() > 0 && mayHaveEqualityDeletes(snapshot);
+    boolean mayHaveEqualityDeletes = !deleteManifests.isEmpty() && mayHaveEqualityDeletes(snapshot);
     boolean planDeletesLocally = shouldPlanDeletesLocally(deleteManifests, mayHaveEqualityDeletes);
 
     List<ManifestFile> dataManifests = findMatchingDataManifests(snapshot);

core/src/main/java/org/apache/iceberg/BaseIncrementalChangelogScan.java

@@ -104,7 +104,7 @@ private Deque<Snapshot> orderedChangelogSnapshots(Long fromIdExcl, long toIdIncl
 
     for (Snapshot snapshot : SnapshotUtil.ancestorsBetween(table(), toIdIncl, fromIdExcl)) {
       if (!snapshot.operation().equals(DataOperations.REPLACE)) {
-        if (snapshot.deleteManifests(table().io()).size() > 0) {
+        if (!snapshot.deleteManifests(table().io()).isEmpty()) {
           throw new UnsupportedOperationException(
               "Delete files are currently not supported in changelog scans");
         }

core/src/main/java/org/apache/iceberg/BaseOverwriteFiles.java

@@ -149,7 +149,7 @@ protected void validate(TableMetadata base, Snapshot parent) {
         validateDeletedDataFiles(base, startingSnapshotId, filter, parent);
       }
 
-      if (deletedDataFiles.size() > 0) {
+      if (!deletedDataFiles.isEmpty()) {
         validateNoNewDeletesForDataFiles(
             base, startingSnapshotId, conflictDetectionFilter, deletedDataFiles, parent);
       }

core/src/main/java/org/apache/iceberg/BaseRewriteFiles.java

@@ -134,7 +134,7 @@ public BaseRewriteFiles toBranch(String branch) {
   @Override
   protected void validate(TableMetadata base, Snapshot parent) {
     validateReplacedAndAddedFiles();
-    if (replacedDataFiles.size() > 0) {
+    if (!replacedDataFiles.isEmpty()) {
       // if there are replaced data files, there cannot be any new row-level deletes for those data
       // files
       validateNoNewDeletesForDataFiles(base, startingSnapshotId, replacedDataFiles, parent);

core/src/main/java/org/apache/iceberg/FastAppend.java

@@ -206,7 +206,7 @@ private List<ManifestFile> writeNewManifests() throws IOException {
       newManifests = null;
     }
 
-    if (newManifests == null && newFiles.size() > 0) {
+    if (newManifests == null && !newFiles.isEmpty()) {
       RollingManifestWriter<DataFile> writer = newRollingManifestWriter(spec);
       try {
         newFiles.forEach(writer::add);

core/src/main/java/org/apache/iceberg/ManifestFilterManager.java

@@ -166,9 +166,9 @@ void delete(CharSequence path) {
   }
 
   boolean containsDeletes() {
-    return deletePaths.size() > 0
+    return !deletePaths.isEmpty()
         || deleteExpression != Expressions.alwaysFalse()
-        || dropPartitions.size() > 0;
+        || !dropPartitions.isEmpty();
   }
 
   /**
@@ -335,7 +335,7 @@ private boolean canContainDeletedFiles(ManifestFile manifest) {
     }
 
     boolean canContainDroppedPartitions;
-    if (dropPartitions.size() > 0) {
+    if (!dropPartitions.isEmpty()) {
       canContainDroppedPartitions =
           ManifestFileUtil.canContainAny(manifest, dropPartitions, specsById);
     } else {
@@ -345,7 +345,7 @@ private boolean canContainDeletedFiles(ManifestFile manifest) {
     boolean canContainDroppedFiles;
     if (hasPathOnlyDeletes) {
       canContainDroppedFiles = true;
-    } else if (deletePaths.size() > 0) {
+    } else if (!deletePaths.isEmpty()) {
       // because there were no path-only deletes, the set of deleted file partitions is valid
       canContainDroppedFiles =
           ManifestFileUtil.canContainAny(manifest, deleteFilePartitions, specsById);

core/src/main/java/org/apache/iceberg/MergingSnapshotProducer.java

@@ -218,11 +218,11 @@ protected boolean deletesDeleteFiles() {
   }
 
   protected boolean addsDataFiles() {
-    return newDataFiles.size() > 0;
+    return !newDataFiles.isEmpty();
   }
 
   protected boolean addsDeleteFiles() {
-    return newDeleteFilesBySpec.size() > 0;
+    return !newDeleteFilesBySpec.isEmpty();
   }
 
   /** Add a data file to the new snapshot. */
@@ -937,7 +937,7 @@ protected void cleanUncommitted(Set<ManifestFile> committed) {
 
   private Iterable<ManifestFile> prepareNewDataManifests() {
     Iterable<ManifestFile> newManifests;
-    if (newDataFiles.size() > 0) {
+    if (!newDataFiles.isEmpty()) {
       List<ManifestFile> dataFileManifests = newDataFilesAsManifests();
       newManifests = Iterables.concat(dataFileManifests, appendManifests, rewrittenAppendManifests);
     } else {
@@ -987,7 +987,7 @@ private Iterable<ManifestFile> prepareDeleteManifests() {
   }
 
   private List<ManifestFile> newDeleteFilesAsManifests() {
-    if (hasNewDeleteFiles && cachedNewDeleteManifests.size() > 0) {
+    if (hasNewDeleteFiles && !cachedNewDeleteManifests.isEmpty()) {
       for (ManifestFile cachedNewDeleteManifest : cachedNewDeleteManifests) {
         deleteFile(cachedNewDeleteManifest.path());
       }

core/src/main/java/org/apache/iceberg/PositionDeletesTable.java

@@ -132,7 +132,7 @@ private Schema calculateSchema() {
                 Types.StringType.get(),
                 MetadataColumns.FILE_PATH_COLUMN_DOC));
 
-    if (partitionType.fields().size() > 0) {
+    if (!partitionType.fields().isEmpty()) {
       return result;
     } else {
       // avoid returning an empty struct, which is not always supported.

core/src/main/java/org/apache/iceberg/ReachableFileUtil.java

@@ -72,7 +72,7 @@ public static Set<String> metadataFileLocations(Table table, boolean recursive)
   private static void metadataFileLocations(
       TableMetadata metadata, Set<String> metadataFileLocations, FileIO io, boolean recursive) {
     List<MetadataLogEntry> metadataLogEntries = metadata.previousFiles();
-    if (metadataLogEntries.size() > 0) {
+    if (!metadataLogEntries.isEmpty()) {
       for (MetadataLogEntry metadataLogEntry : metadataLogEntries) {
         metadataFileLocations.add(metadataLogEntry.file());
       }

core/src/main/java/org/apache/iceberg/SnapshotSummary.java

@@ -192,7 +192,7 @@ public Map<String, String> build() {
       setIf(trustPartitionMetrics, builder, CHANGED_PARTITION_COUNT_PROP, changedPartitions.size());
 
       if (trustPartitionMetrics && changedPartitions.size() <= maxChangedPartitionsForSummaries) {
-        setIf(changedPartitions.size() > 0, builder, PARTITION_SUMMARY_PROP, "true");
+        setIf(!changedPartitions.isEmpty(), builder, PARTITION_SUMMARY_PROP, "true");
         for (String key : changedPartitions) {
           setIf(
               !Strings.isNullOrEmpty(key),

core/src/main/java/org/apache/iceberg/TableMetadata.java

@@ -1383,7 +1383,7 @@ public Builder setPreviousFileLocation(String previousFileLocation) {
 
     private boolean hasChanges() {
       return changes.size() != startingChangeCount
-          || (discardChanges && changes.size() > 0)
+          || (discardChanges && !changes.isEmpty())
           || metadataLocation != null;
     }
 

core/src/main/java/org/apache/iceberg/actions/BaseCommitService.java

@@ -117,9 +117,9 @@ public void start() {
     LOG.info("Starting commit service for {}", table);
     committerService.execute(
         () -> {
-          while (running.get() || completedRewrites.size() > 0 || inProgressCommits.size() > 0) {
+          while (running.get() || !completedRewrites.isEmpty() || !inProgressCommits.isEmpty()) {
             try {
-              if (completedRewrites.size() == 0 && inProgressCommits.size() == 0) {
+              if (completedRewrites.isEmpty() && inProgressCommits.isEmpty()) {
                 // give other threads a chance to make progress
                 Thread.sleep(100);
               }
@@ -129,7 +129,7 @@ public void start() {
             }
 
             // commit whatever is left once done with writing.
-            if (!running.get() && completedRewrites.size() > 0) {
+            if (!running.get() && !completedRewrites.isEmpty()) {
               commitReadyCommitGroups();
             }
           }
@@ -239,7 +239,7 @@ boolean canCreateCommitGroup() {
     // Either we have a full commit group, or we have completed writing and need to commit
     // what is left over
     boolean fullCommitGroup = completedRewrites.size() >= rewritesPerCommit;
-    boolean writingComplete = !running.get() && completedRewrites.size() > 0;
+    boolean writingComplete = !running.get() && !completedRewrites.isEmpty();
     return fullCommitGroup || writingComplete;
   }
 

core/src/main/java/org/apache/iceberg/actions/RewritePositionDeletesGroup.java

@@ -43,7 +43,7 @@ public class RewritePositionDeletesGroup {
   private Set<DeleteFile> addedDeleteFiles = Collections.emptySet();
 
   public RewritePositionDeletesGroup(FileGroupInfo info, List<PositionDeletesScanTask> tasks) {
-    Preconditions.checkArgument(tasks.size() > 0, "Tasks must not be empty");
+    Preconditions.checkArgument(!tasks.isEmpty(), "Tasks must not be empty");
     this.info = info;
     this.tasks = tasks;
     this.maxRewrittenDataSequenceNumber =

core/src/main/java/org/apache/iceberg/io/DeleteWriteResult.java

@@ -62,6 +62,6 @@ public CharSequenceSet referencedDataFiles() {
   }
 
   public boolean referencesDataFiles() {
-    return referencedDataFiles != null && referencedDataFiles.size() > 0;
+    return referencedDataFiles != null && !referencedDataFiles.isEmpty();
   }
 }

core/src/main/java/org/apache/iceberg/util/PartitionUtil.java

@@ -64,7 +64,7 @@ private PartitionUtil() {}
 
     // add _partition
     if (partitionType != null) {
-      if (partitionType.fields().size() > 0) {
+      if (!partitionType.fields().isEmpty()) {
         StructLike coercedPartition = coercePartition(partitionType, spec, partitionData);
         idToConstant.put(
             MetadataColumns.PARTITION_COLUMN_ID,

core/src/main/java/org/apache/iceberg/view/ViewMetadata.java

@@ -412,7 +412,7 @@ public ViewMetadata.Builder assignUUID(String newUUID) {
 
     public ViewMetadata build() {
       Preconditions.checkArgument(null != location, "Invalid location: null");
-      Preconditions.checkArgument(versions.size() > 0, "Invalid view: no versions were added");
+      Preconditions.checkArgument(!versions.isEmpty(), "Invalid view: no versions were added");
 
       // when associated with a metadata file, metadata must have no changes so that the metadata
       // matches exactly what is in the metadata file, which does not store changes. metadata