Preconditions

java.lang.Object

io.flutter.util.Preconditions

public final class Preconditions extends Object

Static convenience methods that help a method or constructor check whether it was invoked correctly (that is, whether its preconditions were met).

Method Summary

Modifier and Type

Method

Description

static <T> T

checkNotNull(T reference)

Ensures that an object reference passed as a parameter to the calling method is not null.

static void

checkState(boolean expression)

Ensures the truth of an expression involving the state of the calling instance.

static void

checkState(boolean expression, Object errorMessage)

Ensures the truth of an expression involving the state of the calling instance.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details
- checkNotNull
  
  public static <T> T checkNotNull(T reference)
  
  Ensures that an object reference passed as a parameter to the calling method is not null.
  
  Parameters:
  
  reference - an object reference
  
  Returns:
  
  the non-null reference that was validated
  
  Throws:
  
  NullPointerException - if reference is null
- checkState
  
  public static void checkState(boolean expression)
  
  Ensures the truth of an expression involving the state of the calling instance.
  
  Parameters:
  
  expression - a boolean expression that must be checked to be true
  
  Throws:
  
  IllegalStateException - if expression is false
- checkState
  
  public static void checkState(boolean expression, @Nullable Object errorMessage)
  
  Ensures the truth of an expression involving the state of the calling instance.
  
  Parameters:
  
  expression - a boolean expression that must be checked to be true
  
  errorMessage - the exception message to use if the check fails; will be converted to a string using String.valueOf(Object)
  
  Throws:
  
  IllegalStateException - if expression is false