feat: Finish basic_part2

lib/basic_part2.dart

@@ -11,6 +11,18 @@ void basic_variables() {
   myName = 123;
   print(myName);
 
+  // var list = [
+  //   1,
+  //   "2",
+  //   3.0,
+  //   true,
+  //   () {},
+  //   #symbol,
+  //   Runes("123"),
+  //   [1, 2, 3],
+  //   {"A": 4}
+  // ];
+
   int lineCount;
   assert(lineCount == null); // default value is null
 }
@@ -37,6 +49,25 @@ void basic_control_flow() {
       print("$number 小於等於 0");
   }
 
+  DownloadState downloadState = DownloadState.done;
+
+  switch (downloadState) {
+    case DownloadState.none:
+      print("尚未下載");
+      break;
+    case DownloadState.downloading:
+      print("下載中");
+      break;
+    case DownloadState.done:
+      print("下載完成");
+      break;
+    case DownloadState.error:
+      print("下載失敗");
+      break;
+    default:
+      throw Exception("異常狀態");
+  }
+
   // For loop
   var collection = [];
   for (var i = 0; i < 3; i++) {
@@ -55,7 +86,6 @@ void basic_control_flow() {
   int count = 0;
   while (count < 5) {
     count += 1;
-    // if (count == 3) break;
   }
   print(count);
 
@@ -64,4 +94,26 @@ void basic_control_flow() {
     print("count 加一次 5");
   } while (count < 14);
   print(count);
-}
+
+  // Break Continue
+  count = 0;
+  while (count < 5) {
+    count += 1;
+    if (count == 4) continue;
+  }
+  print(count);
+
+  do {
+    count += 5;
+    print("count 加一次 5");
+    if (count % 2 == 0) break;
+  } while (count < 14);
+  print(count);
+}
+
+enum DownloadState {
+  none,
+  downloading,
+  done,
+  error
+}