fix(pattern-iterator): initialize user reading process in UserFileBatchRead and make batchUserList final in UserFileBatch

Author: helltractor

pattern-design/pattern-iterator/src/main/java/com/helltractor/demo/user/UserFileBatch.java

@@ -31,7 +31,7 @@ private class UserFileBatchIterator implements Iterator<List<User>> {
 
         private boolean finished = false;
         private final BufferedReader reader;
-        private List<User> batchUserList = new ArrayList<>();
+        private final List<User> batchUserList = new ArrayList<>();
 
         UserFileBatchIterator() {
             try {

pattern-design/pattern-iterator/src/main/java/com/helltractor/demo/user/UserFileBatchRead.java

@@ -37,6 +37,7 @@ private class UserFileReadBatchIterator implements Iterator<User> {
         UserFileReadBatchIterator() {
             try {
                 this.reader = new BufferedReader(new FileReader(file));
+                readUsersFromFile();
             } catch (FileNotFoundException e) {
                 throw new RuntimeException("File not found: " + file.getAbsolutePath(), e);
             }
@@ -73,7 +74,7 @@ private void readUsersFromFile() {
 
         @Override
         public boolean hasNext() {
-            if (batchUserList == null || index >= batchUserList.size() && !finished) {
+            if (index >= batchUserList.size() && !finished) {
                 try {
                     readUsersFromFile();
                 } catch (Exception e) {