Example:
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package ravi.tutorial.java.java7; import java.lang.invoke.MethodHandle; import java.lang.invoke.MethodHandles; import java.lang.invoke.MethodType; public class MethodHandleTest { public static void main(String[] args) throws Throwable { /* * Prepare lookup */ MethodHandles.Lookup lookup = MethodHandles.lookup(); /* * Create a method type which has signature as * * Return type = Double, First method argument = Integer, Second method argument * = Long * * This is for matching add method in Calculator class */ MethodType mt = MethodType.methodType(Double.class, Integer.class, Long.class); /* * Get method handle from class Calculator, with method name 'add' and matches * method signature as per mt method type. */ MethodHandle mh = lookup.findVirtual(Calculator.class, "add", mt); /* * Call method on calcObject with method arguments as arg_1 & arg_2 */ Calculator calcObject = new Calculator(); Integer arg_1 = 1; Long arg_2 = 2l; Double output = (Double) mh.invokeExact(calcObject, arg_1, arg_2); System.out.println(output); } } /* * Demo class */ class Calculator { public Double add(Integer a, Long b) { Long l = (a + b); return l.doubleValue(); } } |
Output:
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1 |
3.0 |