原文：https://www.dartlang.org/guides/language/language-tour

• if and else
• for loops
• while and do-while loops
• break and continue
• switch and case
• assert

switch

Dart 的switch支持 integer, string, 或 用==比較編譯時(shí)常量. 被比較的實(shí)列的類必須相同 (不能是任何它的子類),并且不能重載 ==運(yùn)算符.也支持 Enum 類型。

每個(gè)非空 case 以break 語句來結(jié)束. 結(jié)束 case 的其他方法還有 continue, throw, 或者 return 語句.

var command = 'OPEN';
switch (command) {
  case 'CLOSED':
    executeClosed();
    break;
  case 'PENDING':
    executePending();
    break;
  case 'APPROVED':
    executeApproved();
    break;
  case 'DENIED':
    executeDenied();
    break;
  case 'OPEN':
    executeOpen();
    break;
  default:
    executeUnknown();
}

省略號(hào)break會(huì)報(bào)錯(cuò):

var command = 'OPEN';
switch (command) {
  case 'OPEN':
    executeOpen();
    // ERROR: Missing break

  case 'CLOSED':
    executeClosed();
    break;
}

Dart支持空 case分支:

var command = 'CLOSED';
switch (command) {
  case 'CLOSED': // Empty case falls through.
  case 'NOW_CLOSED':
    // Runs for both CLOSED and NOW_CLOSED.
    executeNowClosed();
    break;
}

continue :

var command = 'CLOSED';
switch (command) {
  case 'CLOSED':
    executeClosed();
    continue nowClosed;
  // Continues executing at the nowClosed label.

  nowClosed:
  case 'NOW_CLOSED':
    // Runs for both CLOSED and NOW_CLOSED.
    executeNowClosed();
    break;
}

case 分支可以定義局部變量, 只在此分支內(nèi)可見.