lambda

问题 I have 2 lists. The requirement is to filter out elements in list1 that are not in list2 based on condition. Class Fighter { String name; String address; } List<Fighter> pairs1 = new ArrayList(); pairs1.add(new Fighter("a", "a")); pairs1.add(new Fighter("b", "a")); List<Fighter> pairs2 = new ArrayList(); pairs2.add(new Fighter("a", "c")); pairs2.add(new Fighter("a", "d")); Set<Fighter> finalValues = new HashSet<>(); finalValues = pairs1.stream().filter(firstList -> pairs2.stream().noneMatch

问题 I'm trying to write a wrapper for a "register callback" type of interface from a C library. The issue is quite complicated by the fact that, the library lets you register "variadic" functions by accepting a list of parameter definitions. Then at callback time, the function is expected to extract its arguments from a type-erased list of arguments. Good old C... The interface I'm trying to create is to accept any function, even a lambda, and automatically generate all the machinery to correctly

问题 I'm trying to write a wrapper for a "register callback" type of interface from a C library. The issue is quite complicated by the fact that, the library lets you register "variadic" functions by accepting a list of parameter definitions. Then at callback time, the function is expected to extract its arguments from a type-erased list of arguments. Good old C... The interface I'm trying to create is to accept any function, even a lambda, and automatically generate all the machinery to correctly

问题 I have 2 lists. The requirement is to filter out elements in list1 that are not in list2 based on condition. Class Fighter { String name; String address; } List<Fighter> pairs1 = new ArrayList(); pairs1.add(new Fighter("a", "a")); pairs1.add(new Fighter("b", "a")); List<Fighter> pairs2 = new ArrayList(); pairs2.add(new Fighter("a", "c")); pairs2.add(new Fighter("a", "d")); Set<Fighter> finalValues = new HashSet<>(); finalValues = pairs1.stream().filter(firstList -> pairs2.stream().noneMatch

问题 Suppose I have an object containing a collection, each elements on the said collection contains a collection, and each collection contains a collection. And I want to iterate on the deepest objects and apply the same code to it. The imperative way is trivial, but is there a way to lambda-fy this all? Here is how the code looks today: My object o; SecretType computedThingy = 78; for (FirstLevelOfCollection coll : o.getList()) { for (SecondLevelOfCollection colColl : coll.getSet()) { for

问题 There is a code example in the O Reilly Programming Python book which uses an OR operator in a lambda function. The text states that "[the code] uses an or operator to force two expressions to be run". How and why does this work? widget = Button(None, # but contains just an expression text='Hello event world', command=(lambda: print('Hello lambda world') or sys.exit()) ) widget.pack() widget.mainloop() 回答1: Every funnction in Python returns a value. If there is no explicit return statement it

问题 I would like to know how to be able to make an Expression tree by inputting more than one parameter Example: dataContext.Users.Where(u => u.username == "Username" && u.password == "Password") At the moment the code that I did was the following but would like to make more general in regards whether the condition is OR or AND public Func<TLinqEntity, bool> ANDOnlyParams(string[] paramNames, object[] values) { List<ParameterExpression> paramList = new List<ParameterExpression>(); foreach (string

问题 I am using jack compiler in my android project. My min sdk is set to 18. I am unable to use forEach and lambda in my code. It asks me to change my min sdk to 24 or higher. I was hoping that with the integration of JACK compiler I would be able to use this forEach with lambda easily. Is there any work around for this other than bumping up the min sdk? 来源： https://stackoverflow.com/questions/42276329/unable-to-use-foreach-and-lambda-in-android-min-sdk-version-less-than-24

问题 This question already has answers here : Foreach Control in form, how can I do something to all the TextBoxes in my Form? (14 answers) Closed 3 years ago . I would like to translate this: foreach(Control c in Controls) { if(c is TextBox) { // ... } } Into: foreach(Control c => (c is TextBox) in Controls) { // ... } How can it be done using the lambda function specifically? 回答1: Reference Linq: using System.Linq; And use this: foreach (var control in Controls.Cast<Control>().Where(c => c is

问题 Although it is possible to serialize a lambda in Java 8, it is strongly discouraged; even serializing inner classes is discouraged. The reason given is that lambdas may not deserialize properly on another JRE. However, doesn't this mean that there is a way to safely serialize a lambda? For example, say I define a class to be something like this: public class MyClass { private String value; private Predicate<String> validateValue; public MyClass(String value, Predicate<String> validate) { this