ok queue, Stack

luoziyihao · luoziyihao · commit 306b41b32567 · 2017-02-26T14:23:37.000+08:00
diff --git a/group17/1204187480/code/homework/basic/src/main/java/com/coding/basic/Queue.java b/group17/1204187480/code/homework/basic/src/main/java/com/coding/basic/Queue.java
@@ -1,19 +1,24 @@
 package com.coding.basic;
 
+import java.util.Arrays;
+
 public class Queue {
-	
-	public void enQueue(Object o){		
+
+	private LinkedList elementData = new LinkedList();
+
+	public void enQueue(Object o){
+		elementData.add(o);
 	}
 	
 	public Object deQueue(){
-		return null;
+		return elementData.remove(0);
 	}
 	
 	public boolean isEmpty(){
-		return false;
+		return size() == 0;
 	}
 	
 	public int size(){
-		return -1;
+		return elementData.size();
 	}
 }
diff --git a/group17/1204187480/code/homework/basic/src/main/java/com/coding/basic/Stack.java b/group17/1204187480/code/homework/basic/src/main/java/com/coding/basic/Stack.java
@@ -3,20 +3,28 @@
 public class Stack {
 	private ArrayList elementData = new ArrayList();
 	
-	public void push(Object o){		
+	public void push(Object o){
+		elementData.add(o);
 	}
 	
 	public Object pop(){
-		return null;
+		if (isEmpty()) {
+			throw new IllegalStateException("the stack is empty");
+		}
+		return elementData.remove(elementData.size() - 1);
 	}
 	
 	public Object peek(){
-		return null;
+		if (isEmpty()) {
+			throw new IllegalStateException("the stack is empty");
+		}
+		return elementData.get(elementData.size() - 1);
 	}
+
 	public boolean isEmpty(){
-		return false;
+		return size() == 0;
 	}
 	public int size(){
-		return -1;
+		return elementData.size();
 	}
 }

Original file line number	Diff line number	Diff line change
`@@ -1,19 +1,24 @@`
`1`	`1`	`package com.coding.basic;`
`2`	`2`
	`3`	`+import java.util.Arrays;`
	`4`	`+`
`3`	`5`	`public class Queue {`
`4`		`-`
`5`		`- public void enQueue(Object o){`
	`6`	`+`
	`7`	`+ private LinkedList elementData = new LinkedList();`
	`8`	`+`
	`9`	`+ public void enQueue(Object o){`
	`10`	`+ elementData.add(o);`
`6`	`11`	`}`
`7`	`12`
`8`	`13`	`public Object deQueue(){`
`9`		`- return null;`
	`14`	`+ return elementData.remove(0);`
`10`	`15`	`}`
`11`	`16`
`12`	`17`	`public boolean isEmpty(){`
`13`		`- return false;`
	`18`	`+ return size() == 0;`
`14`	`19`	`}`
`15`	`20`
`16`	`21`	`public int size(){`
`17`		`- return -1;`
	`22`	`+ return elementData.size();`
`18`	`23`	`}`
`19`	`24`	`}`
Original file line number	Diff line number	Diff line change
`@@ -3,20 +3,28 @@`
`3`	`3`	`public class Stack {`
`4`	`4`	`private ArrayList elementData = new ArrayList();`
`5`	`5`
`6`		`- public void push(Object o){`
	`6`	`+ public void push(Object o){`
	`7`	`+ elementData.add(o);`
`7`	`8`	`}`
`8`	`9`
`9`	`10`	`public Object pop(){`
`10`		`- return null;`
	`11`	`+ if (isEmpty()) {`
	`12`	`+ throw new IllegalStateException("the stack is empty");`
	`13`	`+ }`
	`14`	`+ return elementData.remove(elementData.size() - 1);`
`11`	`15`	`}`
`12`	`16`
`13`	`17`	`public Object peek(){`
`14`		`- return null;`
	`18`	`+ if (isEmpty()) {`
	`19`	`+ throw new IllegalStateException("the stack is empty");`
	`20`	`+ }`
	`21`	`+ return elementData.get(elementData.size() - 1);`
`15`	`22`	`}`
	`23`	`+`
`16`	`24`	`public boolean isEmpty(){`
`17`		`- return false;`
	`25`	`+ return size() == 0;`
`18`	`26`	`}`
`19`	`27`	`public int size(){`
`20`		`- return -1;`
	`28`	`+ return elementData.size();`
`21`	`29`	`}`
`22`	`30`	`}`