Fix restart position handling in AbstractPaginatedDataItemReader#jumpToItem

Resolves #5136

Signed-off-by: banseok1216 <[email protected]>

Author: banseok1216

spring-batch-infrastructure/src/main/java/org/springframework/batch/infrastructure/item/data/AbstractPaginatedDataItemReader.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2013-2024 the original author or authors.
+ * Copyright 2013-present the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -118,9 +118,10 @@ protected void jumpToItem(int itemLastIndex) throws Exception {
 
 			Iterator<T> initialPage = doPageRead();
 
-			for (; current >= 0; current--) {
+			for (; current > 0; current--) {
 				initialPage.next();
 			}
+			this.results = initialPage;
 		}
 		finally {
 			this.lock.unlock();

spring-batch-infrastructure/src/test/java/org/springframework/batch/infrastructure/item/data/AbstractPaginatedDataItemReaderTests.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2026-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.batch.infrastructure.item.data;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.batch.infrastructure.item.ExecutionContext;
+
+import java.util.Iterator;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class AbstractPaginatedDataItemReaderTests {
+
+	static class PaginatedDataItemReader extends AbstractPaginatedDataItemReader<Integer> {
+
+		private final List<Integer> data = List.of(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
+				19);
+
+		@Override
+		protected Iterator<Integer> doPageRead() {
+			int start = page * pageSize;
+			int end = Math.min(start + pageSize, data.size());
+			return data.subList(start, end).iterator();
+		}
+
+	}
+
+	@Test
+	void jumpToItem_shouldReadExactItem_afterJump() throws Exception {
+		PaginatedDataItemReader reader = new PaginatedDataItemReader();
+		reader.open(new ExecutionContext());
+
+		reader.jumpToItem(7);
+
+		Integer value = reader.read();
+		assertEquals(7, value);
+	}
+
+	@Test
+	void jumpToItem_zeroIndex() throws Exception {
+		PaginatedDataItemReader reader = new PaginatedDataItemReader();
+		reader.open(new ExecutionContext());
+
+		reader.jumpToItem(0);
+
+		Integer value = reader.read();
+		assertEquals(0, value);
+	}
+
+	@Test
+	void jumpToItem_lastItemInPage() throws Exception {
+		PaginatedDataItemReader reader = new PaginatedDataItemReader();
+		reader.open(new ExecutionContext());
+
+		reader.jumpToItem(9);
+
+		Integer value = reader.read();
+		assertEquals(9, value);
+	}
+
+	@Test
+	void jumpToItem_firstItemOfNextPage() throws Exception {
+		PaginatedDataItemReader reader = new PaginatedDataItemReader();
+		reader.open(new ExecutionContext());
+
+		reader.jumpToItem(10);
+
+		Integer value = reader.read();
+		assertEquals(10, value);
+	}
+
+}

spring-batch-infrastructure/src/test/java/org/springframework/batch/infrastructure/item/database/AbstractPagingItemReaderTests.java

@@ -0,0 +1,93 @@
+/*
+ * Copyright 2026-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.batch.infrastructure.item.database;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.batch.infrastructure.item.ExecutionContext;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class AbstractPagingItemReaderTests {
+
+	static class PagingItemReader extends AbstractPagingItemReader<Integer> {
+
+		private final List<Integer> data = List.of(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
+				19);
+
+		@Override
+		protected void doReadPage() {
+			int start = getPage() * getPageSize();
+			int end = Math.min(start + getPageSize(), data.size());
+
+			if (start >= data.size()) {
+				results = List.of();
+				return;
+			}
+
+			List<Integer> pageData = new ArrayList<>();
+			for (int i = start; i < end; i++) {
+				pageData.add(data.get(i));
+			}
+
+			this.results = pageData;
+		}
+
+		@Override
+		protected void doOpen() {
+		}
+
+	}
+
+	@Test
+	void jumpToItem_shouldReadExactItem_afterJump() throws Exception {
+		PagingItemReader reader = new PagingItemReader();
+		reader.open(new ExecutionContext());
+
+		reader.jumpToItem(7);
+		assertEquals(7, reader.read());
+	}
+
+	@Test
+	void jumpToItem_zeroIndex() throws Exception {
+		PagingItemReader reader = new PagingItemReader();
+		reader.open(new ExecutionContext());
+
+		reader.jumpToItem(0);
+		assertEquals(0, reader.read());
+	}
+
+	@Test
+	void jumpToItem_lastItemInFirstPage() throws Exception {
+		PagingItemReader reader = new PagingItemReader();
+		reader.open(new ExecutionContext());
+
+		reader.jumpToItem(9);
+		assertEquals(9, reader.read());
+	}
+
+	@Test
+	void jumpToItem_firstItemOfNextPage() throws Exception {
+		PagingItemReader reader = new PagingItemReader();
+		reader.open(new ExecutionContext());
+
+		reader.jumpToItem(10);
+		assertEquals(10, reader.read());
+	}
+
+}