I have some functions collected as methods in a class called func. I use those methods quite often in different classes. Is there a way in java to call those functions without creating a new object or calling it like this: func.myFunction();?
I want: myFunction();
There are two issues:
The first one is easy to solve: if your method doesn't actually use any non-static members (fields or methods) of the class, then simply adding the static keyword enables you to call it without an instance of the class:
// in YourClass:
public static void yourMethod() {
//stuff
}
// somewhere else:
YourClass.yourMethod();
And about the second item: I kind-of lied there, you can do that, but you need a static import:
// at the beginning of your .java file
import static yourpackage.YourClass.yourMethod;
// later on in that file:
yourMethod();
Also: there are no functions in Java, only methods.
Yes, you can mark the methods as static, and use static imports.
Example:
pkg/UtilFunctions.java
package pkg;
public class UtilFunctions {
public static int sum(int i1, int i2) {
return i1 + i2;
}
}
Test.java
import static pkg.UtilFunctions.*;
class Test {
public static void main(String[] args) {
int i = sum(5, 7); // Calls UtilFunctions.sum(...)
}
}
Make them static like public static int myFunction(); and then make static import: import static myclass:
Foo.java:
class Foo {
public static int method() {return 42;}
...
}
Bar.java
import static Foo.*;
...
System.out.println(method());
import static myclass won't do, you'll have to import the particular static members of myclass.You can use a static import.
For example this:
import java.lang.Math;
...
System.out.println(Math.abs(-1.4));
and this:
import static java.lang.Math;
...
System.out.println(abs(-1.4));
produce the same result.
