StackUtils finished

group24/448641125/src/com/donaldy/basic/StackUtil.java

@@ -0,0 +1,109 @@
+package com.donaldy.basic;
+
+import java.util.*;
+
+public class StackUtil {
+
+
+	/**
+	 * 假设栈中的元素是Integer, 从栈顶到栈底是 : 5,4,3,2,1 调用该方法后， 元素次序变为: 1,2,3,4,5
+	 * 注意：只能使用Stack的基本操作，即push,pop,peek,isEmpty， 可以使用另外一个栈来辅助
+	 */
+	public static void reverse(Stack s) {
+		Stack stack = new Stack();
+		while (!s.isEmpty()) {
+			Object element = s.pop();
+			stack.push(element);
+		}
+
+		while (!stack.isEmpty()) {
+			Object element = stack.pop();
+			s.push(element);
+		}
+	}
+
+	/**
+	 * 删除栈中的某个元素 注意：只能使用Stack的基本操作，即push,pop,peek,isEmpty， 可以使用另外一个栈来辅助
+	 * 
+	 * @param o
+	 */
+	public static void remove(Stack s,Object o) {
+		//若stack的值为唯一的。
+		Stack stack = new Stack();
+		while (!s.isEmpty()) {
+			Object element = s.pop();
+			if (o == element) {
+				break;
+			}
+			stack.push(element);
+		}
+
+		while (!stack.isEmpty()) {
+			Object element = stack.pop();
+			s.push(element);
+		}
+	}
+
+	/**
+	 * 从栈顶取得len个元素, 原来的栈中元素保持不变
+	 * 注意：只能使用Stack的基本操作，即push,pop,peek,isEmpty， 可以使用另外一个栈来辅助
+	 * @param len
+	 * @return
+	 */
+	public static Object[] getTop(Stack s,int len) {
+		if (len < 0 || len >= s.size())
+			throw new IndexOutOfBoundsException("len : " + len);
+		Object [] arr = new Object[len];
+
+		for (int i = 0 ; i < len && !s.isEmpty(); ++i) {
+			arr[i] = s.pop();
+		}
+		return arr;
+	}
+	/**
+	 * 字符串s 可能包含这些字符：  ( ) [ ] { }, a,b,c... x,yz
+	 * 使用堆栈检查字符串s中的括号是不是成对出现的。
+	 * 例如s = "([e{d}f])" , 则该字符串中的括号是成对出现， 该方法返回true
+	 * 如果 s = "([b{x]y})", 则该字符串中的括号不是成对出现的， 该方法返回false;
+	 * @param s
+	 * @return
+	 */
+	public static boolean isValidPairs(String s){
+		char [] arr = s.toCharArray();
+		Stack stack = new Stack();
+		for (int i = 0; i < s.length(); ++i) {
+			if (arr[i] == '(' )
+				stack.push(')');
+			if ( arr[i] == '{' )
+				stack.push('}');
+			if ( arr[i] == '[')
+				stack.push(']');
+
+			if (arr[i] == ')' ) {
+				if (')' != (char)stack.peek())
+					break;
+				stack.pop();
+			}
+
+			if (arr[i] == '}' ) {
+				if ('}' != (char)stack.peek())
+					break;
+				stack.pop();
+			}
+
+			if (arr[i] == ']' ) {
+				if (']' != (char)stack.peek())
+					break;
+				stack.pop();
+			}
+
+		}
+
+		if (stack.isEmpty())
+			return true;
+
+		return false;
+	}
+
+
+}

group24/448641125/src/com/donaldy/jvm/loader/ClassFileLoader.java

@@ -20,7 +20,7 @@ public byte[] readBinaryCode(String className) {
 		for (String clzPath : clzPaths) {
 
 			File file = new File(clzPath + className.replace(".", "\\") + ".class");
-			
+
 
 			if (!file.exists())
 				continue;

group24/448641125/src/com/donaldy/jvm/test/EmployeeV1.java

@@ -2,7 +2,6 @@
 
 public class EmployeeV1 {
 
-
 	private String name;
     private int age;
 
@@ -23,6 +22,5 @@ public void sayHello() {
     public static void main(String[] args){
     	EmployeeV1 p = new EmployeeV1("Andy",29);
     	p.sayHello();    
-
     }
 }

group24/448641125/src/com/donaldy/test/StackUtilTest.java

@@ -0,0 +1,65 @@
+package com.donaldy.test;
+
+import com.donaldy.basic.Stack;
+import com.donaldy.basic.StackUtil;
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Created by DonaldY on 2017/4/6.
+ */
+public class StackUtilTest {
+
+    @Test
+    public void testReverse() {
+        Stack stack = new Stack();
+        Integer [] intArr = {5, 4, 3, 2, 1};
+        for (int i = 4; i >= 0 ; --i)
+            stack.push(intArr[i]);
+        StackUtil.reverse(stack);
+        for (int i = 0 ; i < 5; ++i) {
+            Assert.assertEquals((int)stack.pop(), (int)intArr[i]);
+        }
+    }
+
+    @Test
+    public void testRemove() {
+        Stack stack = new Stack();
+        Integer [] intArr = {5, 4, 3, 2, 1};
+        for (int i = 4; i >= 0 ; --i)
+            stack.push(intArr[i]);
+
+        StackUtil.remove(stack, 2);
+        for (int i = 0; i < 5; ++i) {
+            if (i == 3)
+                continue;
+            System.out.println("stack: " + stack.peek() + " i :　" + (int) intArr[i]);
+            Assert.assertEquals((int)stack.pop(), (int)intArr[i]);
+        }
+    }
+
+    @Test
+    public void testGetTop() {
+        Stack stack = new Stack();
+        Integer [] intArr = {5, 4, 3, 2, 1};
+        for (int i = 4; i >= 0 ; --i)
+            stack.push(intArr[i]);
+
+        int len = 3;
+        Object [] arr = StackUtil.getTop(stack, len);
+
+        for (int i = 0 ; i < arr.length ; ++i) {
+            Assert.assertEquals((int)arr[i], (int)intArr[i]);
+        }
+    }
+
+    @Test
+    public void testIsValidPairs() {
+
+        String str1 = "([e{d}f])";
+        Assert.assertEquals(true, StackUtil.isValidPairs(str1));
+
+        String str2 = "([b{x]y})";
+        Assert.assertEquals(false, StackUtil.isValidPairs(str2));
+    }
+}