From 49eed9c8a3d4f862c5ff75c08c31c0fe54bf2fbf Mon Sep 17 00:00:00 2001
From: LehiChiang <1471277588@qq.com>
Date: Wed, 12 May 2021 22:56:39 +0800
Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A00225.=E7=94=A8=E9=98=9F?=
 =?UTF-8?q?=E5=88=97=E5=AE=9E=E7=8E=B0=E6=A0=88/0232.=E7=94=A8=E6=A0=88?=
 =?UTF-8?q?=E5=AE=9E=E7=8E=B0=E9=98=9F=E5=88=97=20Java=E7=89=88=E6=9C=AC?=
 =?UTF-8?q?=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 problems/0225.用队列实现栈.md | 53 +++++++++++++++++++++++++-
 problems/0232.用栈实现队列.md | 59 +++++++++++++++++++++++++++--
 2 files changed, 107 insertions(+), 5 deletions(-)

diff --git a/problems/0225.用队列实现栈.md b/problems/0225.用队列实现栈.md
index 49b5c62b..4018364a 100644
--- a/problems/0225.用队列实现栈.md
+++ b/problems/0225.用队列实现栈.md
@@ -154,9 +154,58 @@ public:
 
 ## 其他语言版本
 
-
 Java：
 
+```java
+class MyStack {
+
+    Queue<Integer> queue1; // 和栈中保持一样元素的队列
+    Queue<Integer> queue2; // 辅助队列
+
+    /** Initialize your data structure here. */
+    public MyStack() {
+        queue1 = new LinkedList<>();
+        queue2 = new LinkedList<>();
+    }
+    
+    /** Push element x onto stack. */
+    public void push(int x) {
+        queue2.offer(x); // 先放在辅助队列中
+        while (!queue1.isEmpty()){
+            queue2.offer(queue1.poll());
+        }
+        Queue<Integer> queueTemp;
+        queueTemp = queue1;
+        queue1 = queue2;
+        queue2 = queueTemp; // 最后交换queue1和queue2，将元素都放到queue1中
+    }
+    
+    /** Removes the element on top of the stack and returns that element. */
+    public int pop() {
+        return queue1.poll(); // 因为queue1中的元素和栈中的保持一致，所以这个和下面两个的操作只看queue1即可
+    }
+    
+    /** Get the top element. */
+    public int top() {
+        return queue1.peek();
+    }
+    
+    /** Returns whether the stack is empty. */
+    public boolean empty() {
+        return queue1.isEmpty();
+    }
+}
+
+/**
+ * Your MyQueue object will be instantiated and called as such:
+ * MyQueue obj = new MyQueue();
+ * obj.push(x);
+ * int param_2 = obj.pop();
+ * int param_3 = obj.peek();
+ * boolean param_4 = obj.empty();
+ */
+```
+
 
 Python：
 
@@ -227,4 +276,4 @@ Go：
 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
 * B站视频：[代码随想录](https://space.bilibili.com/525438321)
 * 知识星球：[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ)
-<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
+<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
\ No newline at end of file
diff --git a/problems/0232.用栈实现队列.md b/problems/0232.用栈实现队列.md
index 9907b476..abdc363d 100644
--- a/problems/0232.用栈实现队列.md
+++ b/problems/0232.用栈实现队列.md
@@ -19,7 +19,7 @@ push(x) -- 将一个元素放入队列的尾部。
 pop() -- 从队列首部移除元素。
 peek() -- 返回队列首部的元素。
 empty() -- 返回队列是否为空。
- 
+
 
 示例:
 
@@ -129,9 +129,62 @@ public:
 
 ## 其他语言版本
 
-
 Java：
 
+```java
+class MyQueue {
+
+    Stack<Integer> stack1;
+    Stack<Integer> stack2;
+
+    /** Initialize your data structure here. */
+    public MyQueue() {
+        stack1 = new Stack<>(); // 负责进栈
+        stack2 = new Stack<>(); // 负责出栈
+    }
+    
+    /** Push element x to the back of queue. */
+    public void push(int x) {
+        stack1.push(x);
+    }
+    
+    /** Removes the element from in front of queue and returns that element. */
+    public int pop() {    
+        dumpStack1();
+        return stack2.pop();
+    }
+    
+    /** Get the front element. */
+    public int peek() {
+        dumpStack1();
+        return stack2.peek();
+    }
+    
+    /** Returns whether the queue is empty. */
+    public boolean empty() {
+        return stack1.isEmpty() && stack2.isEmpty();
+    }
+
+    // 如果stack2为空，那么将stack1中的元素全部放到stack2中
+    private void dumpStack1(){
+        if (stack2.isEmpty()){
+            while (!stack1.isEmpty()){
+                stack2.push(stack1.pop());
+            }
+        }
+    }
+}
+
+/**
+ * Your MyQueue object will be instantiated and called as such:
+ * MyQueue obj = new MyQueue();
+ * obj.push(x);
+ * int param_2 = obj.pop();
+ * int param_3 = obj.peek();
+ * boolean param_4 = obj.empty();
+ */
+```
+
 
 Python：
 
@@ -145,4 +198,4 @@ Go：
 * 作者微信：[程序员Carl](https://mp.weixin.qq.com/s/b66DFkOp8OOxdZC_xLZxfw)
 * B站视频：[代码随想录](https://space.bilibili.com/525438321)
 * 知识星球：[代码随想录](https://mp.weixin.qq.com/s/QVF6upVMSbgvZy8lHZS3CQ)
-<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
+<div align="center"><img src=../pics/公众号.png width=450 alt=> </img></div>
\ No newline at end of file