Dart开发之——异常处理

发表于 2021-02-07 分类于开发， C-前端开发， Dart 阅读时长 ≈ 1 分钟

一概述

Dart中的异常
Dart中的异常处理

二 Dart中的异常

2.1 说明

Dart使用throw关键字抛出异常
throw("异常")或throw "异常"

2.2 代码示例

main() {
  var a = -1;
  if (a < 0) {
    throw "异常";
  }
}

打印：

Unhandled exception:
异常
#0      main (file:///D:/Code/Dart/DartWhile/src/exception/MainException.dart:4:5)
#1      _delayEntrypointInvocation.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:283:19)
#2      _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:184:12)

三 Dart中的异常处理

3.1 异常处理说明

当使用try处理异常语句时，显示下列内容(try后可接：on/catch/finally)

1 2	A try block must be followed by an 'on', 'catch', or 'finally' clause. Try adding either a catch or finally clause, or remove the try statement.

3.2 try..on

main() {
  var a = -1;
  try {
    if (a < 0) {
      throw ("异常");
    }
  } on int {
    print("捕获了整数类型的异常");
  } on String {
    print("捕获了字符串类型的异常");
  }
  print("程序完成");
}

3.3 try..catch

main() {
  var a = -1;
  try {
    if (a < 0) {
      throw ("异常");
    }
  } catch(ex) {
    print("捕获了异常:$ex");
  }
  print("程序完成");
}

3.4 try..catch..finally

main() {
  var a = -1;
  try {
    if (a < 0) {
      throw ("异常");
    }
  } catch (ex) {
    print("捕获了异常:$ex");
  } finally {
    print("异常处理结束");
  }
  print("程序完成");
}

0%