Prerequisite : Java.lang.Class class in Java | Set 1, Java.lang.Class class in Java | Set 2
The java.lang.reflectMethod Class help in getting information of a single method on a class or interface. This class also provides access to the methods of classes and invoke them at runtime.
The getReturnType() method of Method class
Every Method has a return type whether it is void, int, double, string or any other datatype. The getReturnType() method of Method class returns a Class object that represent the return type, declared in method at time of creating the method.
Syntax:
public Class<?> getReturnType()
Parameters: The method does not take any parameters.
Return Value: The method returns a Class object that represent the formal return type of the method object.
Below programs illustrate the getReturnType() method of Method class :
Program 1: Below program prints Return Type for some specific methods of a class provided as input in main method of program.
Java
/** Program Demonstrate how to apply getReturnType() method* of Method Class.*/import java.lang.reflect.Method;public class GFG { // Main method public static void main(String[] args) { try { // Create class object Class classobj = demoForReturnParam.class; // Get Method Object Method[] methods = classobj.getMethods(); // Iterate through methods for (Method method : methods) { // We are only taking method defined in the demo class // We are not taking other methods of the object class if (method.getName().equals("setValue") || method.getName().equals("getValue") || method.getName().equals("setManyValues")) { // apply getReturnType() method Class returnParam = method.getReturnType(); // print return Type class object of method Object System.out.println("\nMethod Name : " + method.getName()); System.out.println("Return Type Details: " + returnParam.getName()); } } } catch (Exception e) { e.printStackTrace(); } }}// A simple classclass demoForReturnParam { // Method returning int value public int setValue() { System.out.println("setValue"); return 24; } // Method returning string value public String getValue() { System.out.println("getValue"); return "getValue"; } // Method returning nothing public void setManyValues(int value1, String value3) { System.out.println("setManyValues"); }} |
Method Name : setManyValues Return Type Details: void Method Name : getValue Return Type Details: java.lang.String Method Name : setValue Return Type Details: int
Program 2: Below program prints Return Type for all the methods of a class provided in main method of program.
Java
/** Program Demonstrate how to apply getReturnType() method* of Method Class.*/import java.lang.reflect.Method;public class GFG { // Main method public static void main(String[] args) { try { // Create class object Class classobj = GFG.class; // Get Method Object Method[] methods = classobj.getMethods(); // Iterate through methods for (Method method : methods) { // Apply getReturnType() method Class returnParam = method.getReturnType(); // Print return Type class object of method Object System.out.println("\nMethod Name : " + method.getName()); System.out.println("Return Type Details: " + returnParam.getName()); } } catch (Exception e) { e.printStackTrace(); } } // Method returning int value public int method1() { System.out.println("method1"); return 24; } // Method returning string value public String method2() { System.out.println("method2"); return "method3"; } // Method returning nothing public void method3(int value1, String value3) { System.out.println("method3"); }} |
Method Name : method3 Return Type Details: void Method Name : method2 Return Type Details: java.lang.String Method Name : method1 Return Type Details: int Method Name : main Return Type Details: void Method Name : wait Return Type Details: void Method Name : wait Return Type Details: void Method Name : wait Return Type Details: void Method Name : equals Return Type Details: boolean Method Name : toString Return Type Details: java.lang.String Method Name : hashCode Return Type Details: int Method Name : getClass Return Type Details: java.lang.Class Method Name : notify Return Type Details: void Method Name : notifyAll Return Type Details: void
Explanation: Output of this program also showing results for method objects other than methods defined in class object like wait, equals, toString, hashCode, getClass, notify, notifyAll. These methods are inherited from super class name Object of java.lang lang package by class object.
Reference:
Oracle Doc for getReturnType()
