diff --git a/api/@ohos.util.Deque.d.ts b/api/@ohos.util.Deque.d.ts
index e09c64cf804db29c28705850dbad6746e6347619..e18d3b81524ce8e694d61dec5c2ad7e31f234553 100644
--- a/api/@ohos.util.Deque.d.ts
+++ b/api/@ohos.util.Deque.d.ts
@@ -231,14 +231,14 @@ declare class Deque<T> {
   /**
    * Obtains the header element of a deque.
    *
-   * @returns { T | undefined } the first element of the deque if it exists, otherwise returns undefined.
+   * @returns { T } the first element of the deque.
    * @syscap SystemCapability.Utils.Lang
    * @crossplatform
    * @atomicservice
    * @since 20
    * @arkts 1.2
    */
-  getFirst(): T | undefined;
+  getFirst(): T;
 
   /**
    * Obtains the end element of a deque.
@@ -272,14 +272,14 @@ declare class Deque<T> {
   /**
    * Obtains the end element of a deque.
    *
-   * @returns { T | undefined } the last element of the deque if it exists, otherwise returns undefined.
+   * @returns { T } the last element of the deque if it exists, otherwise returns undefined.
    * @syscap SystemCapability.Utils.Lang
    * @crossplatform
    * @atomicservice
    * @since 20
    * @arkts 1.2
    */
-  getLast(): T | undefined;
+  getLast(): T;
 
   /**
    * Obtains the header element of a deque and delete the element.
@@ -313,14 +313,14 @@ declare class Deque<T> {
   /**
    * Obtains the header element of a deque and delete the element.
    *
-   * @returns { T | undefined } the deleted element of the deque if it exists, otherwise returns undefined.
+   * @returns { T } the deleted element of the deque if it exists, otherwise returns undefined.
    * @syscap SystemCapability.Utils.Lang
    * @crossplatform
    * @atomicservice
    * @since 20
    * @arkts 1.2
    */
-  popFirst(): T | undefined;
+  popFirst(): T;
 
   /**
    * Obtains the end element of a deque and delete the element.
@@ -354,14 +354,14 @@ declare class Deque<T> {
   /**
    * Obtains the end element of a deque and delete the element.
    *
-   * @returns { T | undefined } the deleted element of the deque if it exists, otherwise returns undefined.
+   * @returns { T } the deleted element of the deque if it exists, otherwise returns undefined.
    * @syscap SystemCapability.Utils.Lang
    * @crossplatform
    * @atomicservice
    * @since 20
    * @arkts 1.2
    */
-  popLast(): T | undefined;
+  popLast(): T;
 
   /**
    * Executes a provided function once for each value in the deque object.
diff --git a/api/@ohos.util.LinkedList.d.ts b/api/@ohos.util.LinkedList.d.ts
index 992800277850d44dce5020f2c1a8a514326f34bc..c74e0d85712413cfda71f0113483d0148febd628 100644
--- a/api/@ohos.util.LinkedList.d.ts
+++ b/api/@ohos.util.LinkedList.d.ts
@@ -235,14 +235,14 @@ declare class LinkedList<T> {
    * Obtains an element at the specified position in this container.
    *
    * @param { int } index - specified position
-   * @returns { T | undefined} the element at the specified index, or undefined if the index is out of range.
+   * @returns { T } the element at the specified index, or undefined if the index is out of range.
    * @syscap SystemCapability.Utils.Lang
    * @crossplatform
    * @atomicservice
    * @since 20
    * @arkts 1.2
    */
-  get(index: int): T | undefined;
+  get(index: int): T;
 
   /**
    * Inserts the specified element at the beginning of this LinkedList.
@@ -683,14 +683,14 @@ declare class LinkedList<T> {
   /**
    * Obtains the first element in this container.
    *
-   * @returns { T | undefined } the T type, returns undefined if linkedList is empty
+   * @returns { T } the T type, returns undefined if linkedList is empty
    * @syscap SystemCapability.Utils.Lang
    * @crossplatform
    * @atomicservice
    * @since 20
    * @arkts 1.2
    */
-  getFirst(): T | undefined;
+  getFirst(): T;
 
   /**
    * Returns the Last element (the item at index length-1) of this linkedlist.
@@ -726,14 +726,14 @@ declare class LinkedList<T> {
   /**
    * Obtains the last element in this container.
    *
-   * @returns { T | undefined } the T type, returns undefined if linkedList is empty
+   * @returns { T } the T type, returns undefined if linkedList is empty
    * @syscap SystemCapability.Utils.Lang
    * @crossplatform
    * @atomicservice
    * @since 20
    * @arkts 1.2
    */
-  getLast(): T | undefined;
+  getLast(): T;
 
   /**
    * Replaces the element at the specified position in this Vector with the specified element
@@ -790,7 +790,7 @@ declare class LinkedList<T> {
    *
    * @param { int } index - Position index of the target element.
    * @param { T } element - Element to be used for replacement.
-   * @returns { T | undefined } the T type ,returns undefined if linkedList is empty
+   * @returns { T } the T type
    * @throws { BusinessError } 10200001 - The value of index is out of range.
    * 1.Mandatory parameters are left unspecified;
    * 2.Incorrect parameter types;
@@ -801,7 +801,7 @@ declare class LinkedList<T> {
    * @since 20
    * @arkts 1.2
    */
-  set(index: int, element: T): T | undefined;
+  set(index: int, element: T): T;
 
   /**
    * Replaces each element of this linkedlist with the result of applying the operator to that element.
diff --git a/api/@ohos.util.List.d.ts b/api/@ohos.util.List.d.ts
index 7b4aaa6a2e4f86c08bc94be2263b76a47be8b4a5..5d4d25075c206d97832c2e133e26976ce275312d 100644
--- a/api/@ohos.util.List.d.ts
+++ b/api/@ohos.util.List.d.ts
@@ -592,7 +592,7 @@ declare class List<T> {
    *
    * @param { int } index - Position index of the target element.
    * @param { T } element - Element to be used for replacement.
-   * @returns { T | undefined } the T type, returns undefined if linkedList is empty
+   * @returns { T } the T type
    * @throws { BusinessError } 10200001 - The value of "index" is out of range. It must be >= 0 && <= ${length - 1}.
    * Received value is: ${index}
    * @syscap SystemCapability.Utils.Lang
@@ -601,7 +601,7 @@ declare class List<T> {
    * @since 20
    * @arkts 1.2
    */
-  set(index: int, element: T): T | undefined;
+  set(index: int, element: T): T;
   /**
    * Compares the specified object with this list for equality.if the object are the same as this list
    * return true, otherwise return false.
diff --git a/api/@ohos.util.Stack.d.ts b/api/@ohos.util.Stack.d.ts
index 2dc7eedf00c1d69b7e760fa6f11436db8cbd9a8c..8f1366a0a55591cec87bf3c116c04e387ec7285e 100644
--- a/api/@ohos.util.Stack.d.ts
+++ b/api/@ohos.util.Stack.d.ts
@@ -173,14 +173,14 @@ declare class Stack<T> {
    * Looks at the object at the top of this stack without removing it from the stack
    * Return undefined if this stack is empty
    *
-   * @returns { T | undefined } the top value, or undefined if container is empty
+   * @returns { T } the top value
    * @syscap SystemCapability.Utils.Lang
    * @crossplatform
    * @atomicservice
    * @since 20
    * @arkts 1.2
    */
-  peek(): T | undefined;
+  peek(): T;
 
   /**
    * Removes the object at the top of this stack and returns that object as the value of this function
@@ -218,14 +218,14 @@ declare class Stack<T> {
    * Removes the object at the top of this stack and returns that object as the value of this function
    * an exception if the stack is empty
    *
-   * @returns { T | undefined } Stack top value, or undefined if container is empty
+   * @returns { T } Stack top value
    * @syscap SystemCapability.Utils.Lang
    * @crossplatform
    * @atomicservice
    * @since 20
    * @arkts 1.2
    */
-  pop(): T | undefined;
+  pop(): T;
 
   /**
    * Pushes an item onto the top of this stack
diff --git a/api/@ohos.util.TreeMap.d.ts b/api/@ohos.util.TreeMap.d.ts
index 68a1d106d329e89642f8a54e01bc3bd3e0bd4b33..413c6542daa3efc57089029dcb54eb91ea293f7c 100644
--- a/api/@ohos.util.TreeMap.d.ts
+++ b/api/@ohos.util.TreeMap.d.ts
@@ -349,27 +349,27 @@ declare class TreeMap<K, V> {
    * Obtains the first sorted key in the treemap.
    * Or returns undefined if tree map is empty
    *
-   * @returns { K | undefined } the key of the first element if exists, undefined otherwise
+   * @returns { K } the key of the first element
    * @syscap SystemCapability.Utils.Lang
    * @crossplatform
    * @atomicservice
    * @since 20
    * @arkts 1.2
    */
-  getFirstKey(): K | undefined;
+  getFirstKey(): K;
 
   /**
    * Obtains the last sorted key in the treemap.
    * Or returns undefined if tree map is empty
    *
-   * @returns { K | undefined } the key of the last element if exists, undefined otherwise
+   * @returns { K } the key of the last element
    * @syscap SystemCapability.Utils.Lang
    * @crossplatform
    * @atomicservice
    * @since 20
    * @arkts 1.2
    */
-  getLastKey(): K | undefined;
+  getLastKey(): K;
 
   /**
    * Adds all element groups in one map to another map
diff --git a/api/@ohos.util.TreeSet.d.ts b/api/@ohos.util.TreeSet.d.ts
index 9a61949bd4dd0d190e49748dbf9d25fa4fe6964e..8d8eb2b72ca9eb64ebe28ae89205d3589b70854e 100644
--- a/api/@ohos.util.TreeSet.d.ts
+++ b/api/@ohos.util.TreeSet.d.ts
@@ -565,26 +565,26 @@ declare class TreeSet<T> {
   /**
    * Return and delete the first element, returns undefined if tree set is empty
    *
-   * @returns { T | undefined} the value of the first element in the TreeSet if exists, undefined otherwise
+   * @returns { T } the value of the first element in the TreeSet
    * @syscap SystemCapability.Utils.Lang
    * @crossplatform
    * @atomicservice
    * @since 20
    * @arkts 1.2
    */
-  popFirst(): T | undefined;
+  popFirst(): T;
 
   /**
    * Return and delete the last element, returns undefined if tree set is empty
    *
-   * @returns { T | undefined } the value of the last element in the TreeSet if exists, undefined otherwise
+   * @returns { T } the value of the last element in the TreeSet
    * @syscap SystemCapability.Utils.Lang
    * @crossplatform
    * @atomicservice
    * @since 20
    * @arkts 1.2
    */
-  popLast(): T | undefined;
+  popLast(): T;
 
   /**
    * Executes a provided function once for each value in the Set object.