pagination for user posts

src/main/java/com/ziplinegreen/vault/Controller/PostController.java

     }
 
     @GetMapping("/posts/id/{userId}")
-    public Collection<Post> getAllPostsByUserId(@PathVariable Long userId) {
-        return postService.findByUserId(userId);
+    public Page<Post> getAllPostsByUserId(@PathVariable Long userId, Pageable pageable) {
+        return postService.findByUserId(userId, pageable);
     }
 
     @DeleteMapping("/posts/delete")

src/main/java/com/ziplinegreen/vault/Repository/PostRepository.java

 @RepositoryRestResource
 public interface PostRepository extends JpaRepository<Post,Long> {
     Collection<Post> findByUserId(Long userId);
+    Iterable<Post> findAllByUserId(Long userId);
 
 }

src/main/java/com/ziplinegreen/vault/Service/PostService.java

     }
 
     public ResponseEntity deleteAllPosts(Long userId){
-        Iterable<Post> posts = findByUserId(userId);
+        Iterable<Post> posts = postRepository.findByUserId(userId);
         for(Post post: posts){
             deletePost(post.getId());
         }
         return new ResponseEntity<>(HttpStatus.OK);
     }
 
-    public Collection<Post> findByUserId(Long userId) {
-        return postRepository.findByUserId(userId);
+    public Page<Post> findByUserId(Long userId, Pageable pageable) {
+        Iterable<Post> posts = postRepository.findByUserId(userId);
+        List<Post> postList = StreamSupport.stream(posts.spliterator(), false)
+                .collect(Collectors.toList());
+        Collections.reverse(postList);
+
+        int start = (int)pageable.getOffset();
+        int end = (start + pageable.getPageSize()) > postList.size() ? postList.size() : (start + pageable.getPageSize());
+
+        return new PageImpl<Post>(postList.subList(start,end),pageable, postList.size());
     }
 
+
+
     public Post updatePost(Long postId, String message){
         Post post = postRepository.findById(postId).get();
         post.setMessage(message);