RangeError#

Error thrown due to an argument value being outside an accepted range.

Constructors#

RangeError()#

Create a new RangeError with the given message.

@pragma("vm:entry-point")
RangeError(var message) : start = null, end = null, super(message);

RangeError.index() factory#

Creates a new RangeError stating that index is not a valid index into indexable.

An optional name can specify the argument name that has the invalid value, and the message can override the default error description.

The length is the length of indexable at the time of the error. If length is omitted, it defaults to indexable.length.

factory RangeError.index(
  int index,
  dynamic indexable, [
  String? name,
  String? message,
  int? length,
]) = IndexError;

RangeError.range()#

Create a new RangeError for a value being outside the valid range.

The allowed range is from minValue to maxValue, inclusive. If minValue or maxValue are null, the range is infinite in that direction.

For a range from 0 to the length of something, end exclusive, use RangeError.index.

An optional name can specify the argument name that has the invalid value, and the message can override the default error description.

@pragma("vm:entry-point")
RangeError.range(
  num invalidValue,
  int? minValue,
  int? maxValue, [
  String? name,
  String? message,
]) : start = minValue,
     end = maxValue,
     super.value(invalidValue, name, message ?? "Invalid value");

RangeError.value()#

Create a new RangeError with a message for the given value.

An optional name can specify the argument name that has the invalid value, and the message can override the default error description.

RangeError.value(num value, [String? name, String? message])
  : start = null,
    end = null,
    super.value(value, name, message ?? "Value not in range");

Properties#

end final#

The maximum value that value is allowed to assume.

final num? end;

hashCode no setter inherited#

The hash code for this object.

A hash code is a single integer which represents the state of the object that affects operator == comparisons.

All objects have hash codes. The default hash code implemented by Object represents only the identity of the object, the same way as the default operator == implementation only considers objects equal if they are identical (see identityHashCode).

If operator == is overridden to use the object state instead, the hash code must also be changed to represent that state, otherwise the object cannot be used in hash based data structures like the default Set and Map implementations.

Hash codes must be the same for objects that are equal to each other according to operator ==. The hash code of an object should only change if the object changes in a way that affects equality. There are no further requirements for the hash codes. They need not be consistent between executions of the same program and there are no distribution guarantees.

Objects that are not equal are allowed to have the same hash code. It is even technically allowed that all instances have the same hash code, but if clashes happen too often, it may reduce the efficiency of hash-based data structures like HashSet or HashMap.

If a subclass overrides hashCode, it should override the operator == operator as well to maintain consistency.

Inherited from Object.

external int get hashCode;

invalidValue no setter override#

The invalid value.

num? get invalidValue => super.invalidValue;

message final inherited#

Message describing the problem.

Inherited from ArgumentError.

final dynamic message;

name final inherited#

Name of the invalid argument, if available.

Inherited from ArgumentError.

final String? name;

runtimeType no setter inherited#

A representation of the runtime type of the object.

Inherited from Object.

external Type get runtimeType;

stackTrace no setter inherited#

The stack trace at the point where this error was first thrown.

Classes which extend Error will automatically have a stack trace filled in the first time they are thrown by a throw expression.

Inherited from Error.

external StackTrace? get stackTrace;

start final#

The minimum value that value is allowed to assume.

final num? start;

Methods#

noSuchMethod() inherited#

Invoked when a nonexistent method or property is accessed.

A dynamic member invocation can attempt to call a member which doesn't exist on the receiving object. Example:

dynamic object = 1;
object.add(42); // Statically allowed, run-time error

This invalid code will invoke the noSuchMethod method of the integer 1 with an Invocation representing the .add(42) call and arguments (which then throws).

Classes can override noSuchMethod to provide custom behavior for such invalid dynamic invocations.

A class with a non-default noSuchMethod invocation can also omit implementations for members of its interface. Example:

class MockList<T> implements List<T> {
  noSuchMethod(Invocation invocation) {
    log(invocation);
    super.noSuchMethod(invocation); // Will throw.
  }
}
void main() {
  MockList().add(42);
}

This code has no compile-time warnings or errors even though the MockList class has no concrete implementation of any of the List interface methods. Calls to List methods are forwarded to noSuchMethod, so this code will log an invocation similar to Invocation.method(#add, [42]) and then throw.

If a value is returned from noSuchMethod, it becomes the result of the original invocation. If the value is not of a type that can be returned by the original invocation, a type error occurs at the invocation.

The default behavior is to throw a NoSuchMethodError.

Inherited from Object.

@pragma("vm:entry-point")
@pragma("wasm:entry-point")
external dynamic noSuchMethod(Invocation invocation);

toString() inherited#

A string representation of this object.

Some classes have a default textual representation, often paired with a static parse function (like int.parse). These classes will provide the textual representation as their string representation.

Other classes have no meaningful textual representation that a program will care about. Such classes will typically override toString to provide useful information when inspecting the object, mainly for debugging or logging.

Inherited from ArgumentError.

String toString() {
  String? name = this.name;
  String nameString = (name == null) ? "" : " ($name)";
  Object? message = this.message;
  var messageString = (message == null) ? "" : ": ${message}";
  String prefix = "$_errorName$nameString$messageString";
  if (!_hasValue) return prefix;
  // If we know the invalid value, we can try to describe the problem.
  String explanation = _errorExplanation;
  String errorValue = Error.safeToString(invalidValue);
  return "$prefix$explanation: $errorValue";
}

Operators#

operator ==() inherited#

The equality operator.

The default behavior for all Objects is to return true if and only if this object and other are the same object.

Override this method to specify a different equality relation on a class. The overriding method must still be an equivalence relation. That is, it must be:

• Total: It must return a boolean for all arguments. It should never throw.

• Reflexive: For all objects o, o == o must be true.

• Symmetric: For all objects o1 and o2, o1 == o2 and o2 == o1 must either both be true, or both be false.

• Transitive: For all objects o1, o2, and o3, if o1 == o2 and o2 == o3 are true, then o1 == o3 must be true.

The method should also be consistent over time, so whether two objects are equal should only change if at least one of the objects was modified.

If a subclass overrides the equality operator, it should override the hashCode method as well to maintain consistency.

Inherited from Object.

external bool operator ==(Object other);

Static Methods#

checkNotNegative()#

Check that an integer value is non-negative.

Throws if the value is negative.

If name or message are provided, they are used as the parameter name and message text of the thrown error. If name is omitted, it defaults to index.

Returns value if it is not negative.

static int checkNotNegative(int value, [String? name, String? message]) {
  if (value < 0) {
    throw RangeError.range(value, 0, null, name ?? "index", message);
  }
  return value;
}

checkValidIndex()#

Check that index is a valid index into an indexable object.

Throws if index is not a valid index into indexable.

An indexable object is one that has a length and an index-operator [] that accepts an index if 0 <= index < length.

If name or message are provided, they are used as the parameter name and message text of the thrown error. If name is omitted, it defaults to "index".

If length is provided, it is used as the length of the indexable object, otherwise the length is found as indexable.length.

Returns index if it is a valid index.

static int checkValidIndex(
  int index,
  dynamic indexable, [
  String? name,
  int? length,
  String? message,
]) {
  length ??= (indexable.length as int);
  return IndexError.check(
    index,
    length,
    indexable: indexable,
    name: name,
    message: message,
  );
}

checkValidRange()#

Check that a range represents a slice of an indexable object.

Throws if the range is not valid for an indexable object with the given length. A range is valid for an indexable object with a given length

if 0 <= [start] <= [end] <= [length]. An end of null is considered equivalent to length.

The startName and endName defaults to "start" and "end", respectively.

Returns the actual end value, which is length if end is null, and end otherwise.

static int checkValidRange(
  int start,
  int? end,
  int length, [
  String? startName,
  String? endName,
  String? message,
]) {
  // Comparing with `0` as receiver produces better dart2js type inference.
  // Ditto `start > end` below.
  if (0 > start || start > length) {
    startName ??= "start";
    throw RangeError.range(start, 0, length, startName, message);
  }
  if (end != null) {
    if (start > end || end > length) {
      endName ??= "end";
      throw RangeError.range(end, start, length, endName, message);
    }
    return end;
  }
  return length;
}

checkValueInInterval()#

Check that an integer value lies in a specific interval.

Throws if value is not in the interval. The interval is from minValue to maxValue, both inclusive.

If name or message are provided, they are used as the parameter name and message text of the thrown error.

Returns value if it is in the interval.

static int checkValueInInterval(
  int value,
  int minValue,
  int maxValue, [
  String? name,
  String? message,
]) {
  if (value < minValue || value > maxValue) {
    throw RangeError.range(value, minValue, maxValue, name, message);
  }
  return value;
}