Question

我正在调试应用程序，但是我需要即时了解一些值，我想知道是否有一种方法可以使用Javascript在console.log这样的控制台中打印消息。

感谢您的帮助。

Answer 1

print()可能正是您想要的。 Here's有关在flutter中进行调试的更多信息。

Answer 2

我倾向于做类似的事情

Foo foo;
try{
    foo = _someMethod(); //some method that returns a new object
} catch (e) {
    print('_someMethod: Foo Error ${foo.id} Error:{e.toString()}'); /*my custom error print message. You don't need brackets if you are printing a string variable.*/
}

Answer 3

您可以使用

print()

功能或

debugPrint()

debugPrint（）函数可以打印大量输出。

Answer 4

print，debugPrint和其他语言有一些字数限制，如果要在控制台上打印一些内容，可以：

创建此方法：

void printWrapped(String text) {
  final pattern = RegExp('.{1,800}'); // 800 is the size of each chunk
  pattern.allMatches(text).forEach((match) => print(match.group(0)));
}

用法：

printWrapped("Your very long string ...");

Source

Answer 5

RaisedButton(
    child: Text("Click Me"),
    onPressed: () {
        print("This is a print()");
        debugPrint("This is a debugPrint()");
    },
),

您可以使用print()或debugPrint()方法将输出打印到控制台。

Answer 6

使用调试打印来避免登录生产应用程序。

debugPrint("Message");

您还可以在main.dart或任何其他文件中禁用或更改调试打印实现：

debugPrint = (String message, {int wrapWidth}) 
{
    debugPrintThrottled(message);//Or another other custom code
};

Answer 7

import 'dart:developer'库中还有更多有用的方法，其中之一是 log() 。

示例：

int i = 5;
log("Index number is: $i");

//output
[log] Index number is: 5

void log（字符串消息，{DateTime时间，int sequenceNumber，int级别   = 0，字符串名称=''，区域区域，对象错误，StackTrace stackTrace}）

发出日志事件。

此功能旨在紧密映射到日志记录信息   通过package：logging收集。
[message] is the log message
[time] (optional) is the timestamp
[sequenceNumber] (optional) is a monotonically increasing sequence number
[level] (optional) is the severity level (a value between 0 and 2000); see the package:logging Level class for an overview of the
可能的值 [name]（可选）是日志消息来源的名称 [zone]（可选）发出日志的区域 [错误]（可选）与此日志事件关联的错误对象 [stackTrace]（可选）与此日志事件关联的堆栈跟踪

Read more.：

print()来自dart：core及其实现：

/// Prints a string representation of the object to the console.
void print(Object object) {
  String line = "$object";
  if (printToZone == null) {
    printToConsole(line);
  } else {
    printToZone(line);
  }
}

debugPrint()：

/// Prints a message to the console, which you can access using the "flutter"
/// tool's "logs" command ("flutter logs").
///
/// If a wrapWidth is provided, each line of the message is word-wrapped to that
/// width. (Lines may be separated by newline characters, as in '\n'.)
///
/// By default, this function very crudely attempts to throttle the rate at
/// which messages are sent to avoid data loss on Android. This means that
/// interleaving calls to this function (directly or indirectly via, e.g.,
/// [debugDumpRenderTree] or [debugDumpApp]) and to the Dart [print] method can
/// result in out-of-order messages in the logs

// read more here: https://api.flutter.dev/flutter/foundation/debugPrint.html
DebugPrintCallback debugPrint = debugPrintThrottled;


/// Alternative implementation of [debugPrint] that does not throttle.
/// Used by tests. 
debugPrintSynchronously(String message, { int wrapWidth })

/// Implementation of [debugPrint] that throttles messages. This avoids dropping
/// messages on platforms that rate-limit their logging (for example, Android).
void debugPrintThrottled(String message, { int wrapWidth })

Read more。

请注意，只有print()具有任何类型并打印到控制台。 debugPrint()和log()仅占String。因此，您必须添加.toString()或使用字符串插值，如我在提供的示例代码片段中所示。

Answer 8

您可以在JavaScript中简单地使用与print('whatever you want to print')相同的console.log()。

有关更多信息，您可以check here。

Answer 9

我认为这可能对您有所帮助，因为我在了解 dart 文件中代码的输出方面也遇到了很多困难，因此我按照视频中显示的步骤找到了解决方案。

https://www.youtube.com/watch?v=hhP1tE-IHos

在这里，我展示了一个在观看视频后如何工作的实例。检查左侧列，其中显示了 profile 变量携带的值，即 null

Answer 10

与字符串连接的另一个答案：

// Declaration
int number = 10;


//Button Action
RaisedButton(
child: Text("Subtract Me"),
onPressed: () {
      number = number - 1;
      print('You have got $number as result');
      print('Before Value is ${number - 1} and After value is ${number + 1}');
    },
),

//Output:
flutter: You have got 9 as result
flutter: Before Value is 8 and After value is 10

有没有办法用Flutter打印控制台消息？

10 个答案: