Use ptype. If you use it by itself, you get the declared type of the pointer: (gdb) ptype ptr type = class SuperClass { // various members } * To get the actual type of the object pointed to, set the “print object” variable: (gdb) set print object on (gdb) ptype ptr type = /* … Read more
The simplest approach is to have the Event provide a method you can call so the Event knows what to do. interface Event { public void onEvent(Context context); } class DocumentEvent implements Event { public void onEvent(Context context) { context.getDocumentGenerator().gerenateDocument(this); } } class MailEvent implements Event { public void onEvent(Context context) { context.getDeliveryManager().deliverMail(event); } } … Read more
First of all, we can store instances of classes that implements a particular interface in an interface reference variable like this. package com.test; public class Test implements Testable { public static void main(String[] args) { Testable testable = new Test(); // OR Test test = new Test(); if (testeable instanceof Testable) System.out.println(“instanceof succeeded”); if (test … Read more
Let’s read the docs: The following table lists the operators in order of precedence, with the highest-precedence ones at the top.[…] Associativity Operators Additional Information ================== =============== ====================== non-associative instanceof types right ! logical So instanceof has higher priority, thus both statements are equivalent. Parenthesis are probably used to make it obvious so you don’t … Read more
You can use the is operator to check whether an object is of a specific type: val number = 5 if(number is Int) { println(“number is of type Int”) } You can also get the type as String using reflection: println(Int::class.simpleName) // “Int” println(Int::class.qualifiedName) // “kotlin.Int” Please note: On the Java platform, the runtime component … Read more
For simply checking against Object or Array without additional function call (speed). isArray() let isArray = function(a) { return (!!a) && (a.constructor === Array); }; console.log(isArray( )); // false console.log(isArray( null)); // false console.log(isArray( true)); // false console.log(isArray( 1)); // false console.log(isArray( ‘str’)); // false console.log(isArray( {})); // false console.log(isArray(new Date)); // false console.log(isArray( [])); … Read more
It’s definitely has its place in a stock implementation of equals. E.g. public boolean equals ( Object o ) { if ( this == o ) { return true; } if ( ! (o instanceof MyClass) ) { return false; } // Compare fields … } One neat thing to know about instanceof is that … Read more
The correct syntax would be: Enum.class.isAssignableFrom(test.MyEnum.class) but for enums, here is a more convenient method: if (someObject.getClass().isEnum())) Update: for enum items with a body (e. g. that override methods), this won’t actually work. In that case, use if (someObject instanceof Enum<?>) Reference: Class.isEnum()
You have to read the API carefully for this methods. Sometimes you can get confused very easily. It is either: if (B.class.isInstance(view)) API says: Determines if the specified Object (the parameter) is assignment-compatible with the object represented by this Class (The class object you are calling the method at) or: if (B.class.isAssignableFrom(view.getClass())) API says: Determines … Read more
Because Java has no multiple class inheritance it’s absolutely known during the compilation that obj object of type B cannot be subtype of A. On the other hand it possibly can be subtype of interface C, for example in this case: interface C {} class B {} class D extends B implements C {} public … Read more