Best way to handle multiple constructors in Java
A slightly simplified answer: public class Book { private final String title; public Book(String title) { this.title = title; } public Book() { this(“Default Title”); } … }
field
How can I access a struct field with generics (type T has no field or method)?
Field access has been disabled for Go 1.18 (still disabled in Go 1.19). The Go 1.18 release notes mention this: The current generics implementation has the following known limitations: […] The Go compiler does not support accessing a struct field x.f where x is of type parameter type even if all types in the type … Read more
Loop over all fields in a Java class
Use getDeclaredFields on [Class] ClasWithStuff myStuff = new ClassWithStuff(); Field[] fields = myStuff.getClass().getDeclaredFields(); for(Field f : fields){ Class t = f.getType(); Object v = f.get(myStuff); if(t == boolean.class && Boolean.FALSE.equals(v)) // found default value else if(t.isPrimitive() && ((Number) v).doubleValue() == 0) // found default value else if(!t.isPrimitive() && v == null) // found default value … Read more
Java Lombok: Omitting one field in @AllArgsConstructor?
No that is not possible. There is a feature request to create a @SomeArgsConstructor where you can specify a list of involved fields. Full disclosure: I am one of the core Project Lombok developers.
Retrieve only static fields declared in Java class
You can do it like this: Field[] declaredFields = Test.class.getDeclaredFields(); List<Field> staticFields = new ArrayList<Field>(); for (Field field : declaredFields) { if (java.lang.reflect.Modifier.isStatic(field.getModifiers())) { staticFields.add(field); } }
Javascript – removing undefined fields from an object [duplicate]
A one-liner using ES6 arrow function and ternary operator: Object.keys(obj).forEach(key => obj[key] === undefined ? delete obj[key] : {}); Or use short-circuit evaluation instead of ternary: (@Matt Langlois, thanks for the info!) Object.keys(obj).forEach(key => obj[key] === undefined && delete obj[key]) Same example using if statement: Object.keys(obj).forEach(key => { if (obj[key] === undefined) { delete obj[key]; … Read more
Overriding fields or properties in subclasses
Of the three solutions only Option 1 is polymorphic. Fields by themselves cannot be overridden. Which is exactly why Option 2 returns the new keyword warning. The solution to the warning is not to append the “new” keyword, but to implement Option 1. If you need your field to be polymorphic you need to wrap … Read more
Set field value with reflection
Hope this is something what you are trying to do : import java.lang.reflect.Field; import java.util.HashMap; import java.util.Map; import java.util.concurrent.ConcurrentHashMap; public class Test { private Map ttp = new HashMap(); public void test() { Field declaredField = null; try { declaredField = Test.class.getDeclaredField(“ttp”); boolean accessible = declaredField.isAccessible(); declaredField.setAccessible(true); ConcurrentHashMap<Object, Object> concHashMap = new ConcurrentHashMap<Object, Object>(); concHashMap.put(“key1”, … Read more
Get list of all input objects using JavaScript, without accessing a form object
(See update at end of answer.) You can get a NodeList of all of the input elements via getElementsByTagName (DOM specification, MDC, MSDN), then simply loop through it: var inputs, index; inputs = document.getElementsByTagName(‘input’); for (index = 0; index < inputs.length; ++index) { // deal with inputs[index] element. } There I’ve used it on the … Read more
How to empty input field with jQuery
You can clear the input field by using $(‘#shares’).val(”);