Add a new ListStack class

app/src/main/java/ch/nuth/zhaw/exbox/ListStack.java

@@ -0,0 +1,57 @@
+package ch.nuth.zhaw.exbox;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class ListStack implements Stack {
+    private List<Object> innerList = new ArrayList<>();
+
+    @Override
+    public void push(Object x) throws StackOverflowError {
+        try {
+            if (innerList.add(x)) {
+                return;
+            }
+        }
+        catch (Exception e) {
+            throw new StackOverflowError();
+        }
+    }
+
+    @Override
+    public Object pop() {
+        if (!isEmpty()) {
+            int index = innerList.size() - 1;
+            Object result = innerList.get(index);
+            innerList.remove(index);
+            return result;
+        } else {
+            return null;
+        }
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return innerList.size() == 0;
+    }
+
+    @Override
+    public Object peek() {
+        if (!isEmpty()) {
+            return innerList.get(innerList.size() - 1);
+        } else {
+            return null;
+        }
+    }
+
+    @Override
+    public void removeAll() {
+        innerList.clear();
+    }
+
+    @Override
+    public boolean isFull() {
+        return innerList.size() == Integer.MIN_VALUE;
+    }
+    
+}