解释“cannot unbox null value”错误的含义 "cannot unbox null value" 是一个在Java等强类型语言中常见的运行时错误,尤其是在使用自动装箱(autoboxing)和拆箱(unboxing)机制时。在Java中,基本数据类型(如int, double等)与它们对应的包装类(如Integer, Double等)之间可以自动转换,这种转换分别称为装箱和拆箱。然而...
然后断点,并且将这句话 add to watch 会出现真正的异常:java.lang.NullPointerException: cannot unbox null value 是因为拆箱的时候对象为空,所以拆箱报错,integer对象到int基本类型会自动拆箱。而integer为空,所以报错。
Cannot convert null to 'int' because it is a value type--need help Cannot convert string[] to string in foreach loop Cannot convert type 'System.Collections.Generic.List<Microsoft.Azure.Cosmos.Table.ITableEntity>' to 'System.Collections.Generic.List<ITableEntity>' Cannot convert type 'System...
iles-app@0.0.0 /Users/paul/Projects/Personal/iles-app ├─┬ iles@0.3.11 │├─┬ @islands/frontmatter@0.0.2 ││├── estree-util-is-identifier-name@1.1.0 ││├─┬ estree-util-value-to-estree@1.3.0 │││└── is-plain-obj@3.0.0 ││├─┬ js-yaml@4.1.0 │││└─...
e = ExplicitConversion (ec, unwrap, target, expr.Location);if(e ==null)returnnull;returnnew Nullable.LiftedConversion (e, unwrap, target_type).Resolve (ec); }if(expr_type.BuiltinType == BuiltinTypeSpec.Type.Object) {returnnew UnboxCast (expr, target_type); ...
string } type Names = keyof Types // 'Num' | 'Str' type Inner<T extends Names> = Types[T] interface Box<T extends Names> { type: T value: Inner<T> } // Example of generic operation on Box function unboxExample<T extends Names>(box: Box<T>): Inner<T> { // `box.value` is...
e = ExplicitConversion (ec, unwrap, target, expr.Location);if(e ==null)returnnull;returnnew Nullable.Lifted (e, unwrap, target_type).Resolve (ec); }if(expr_type.BuiltinType == BuiltinTypeSpec.Type.Object) {returnnew UnboxCast (expr, target_type); ...