添加队列和栈的越界检查

zhanglifeng · zhanglifeng · commit 2466967ef16b · 2017-02-26T22:34:21.000+08:00
diff --git a/group05/284422826/src/com/github/zhanglifeng/coding2017/basic/Queue.java b/group05/284422826/src/com/github/zhanglifeng/coding2017/basic/Queue.java
@@ -1,12 +1,17 @@
 package com.github.zhanglifeng.coding2017.basic;
 
+import java.util.EmptyStackException;
+
 public class Queue {
 	private LinkedList elementData = new LinkedList();
 	public void enQueue(Object o){
 		elementData.add(o);
 	}
 	
 	public Object deQueue(){
+		if (elementData.size() == 0) {
+			throw new EmptyStackException();
+		}
 		return elementData.removeFirst();
 	}
 	
diff --git a/group05/284422826/src/com/github/zhanglifeng/coding2017/basic/Stack.java b/group05/284422826/src/com/github/zhanglifeng/coding2017/basic/Stack.java
@@ -1,5 +1,7 @@
 package com.github.zhanglifeng.coding2017.basic;
 
+import java.util.EmptyStackException;
+
 public class Stack {
 	private ArrayList elementData = new ArrayList();
 	
@@ -8,10 +10,16 @@ public void push(Object o){
 	}
 	
 	public Object pop(){
+		if (elementData.size() == 0) {
+			throw new EmptyStackException();
+		}
 		return elementData.remove(elementData.size() - 1);
 	}
 	
 	public Object peek(){
+		if (elementData.size() == 0) {
+			throw new EmptyStackException();
+		}
 		return elementData.get(elementData.size() - 1);
 	}
 	public boolean isEmpty(){
