Return primitive type the passed in wrapper type corresponds to : Data Type Introduction « Data Type « Java Tutorial

import java.util.HashSet;
import java.util.List;
import java.util.Set;

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public class Main {
   * @param wrapper
   *          a primitive wrapper type
   * @return primitive type the passed in wrapper type corresponds to
  public static Class getPrimitive(Class wrapper) {
    Class primitive;
    if (Integer.class == wrapper) {
      primitive = int.class;
    } else if (Long.class == wrapper) {
      primitive = long.class;
    } else if (Double.class == wrapper) {
      primitive = double.class;
    } else if (Boolean.class == wrapper) {
      primitive = boolean.class;
    } else if (Short.class == wrapper) {
      primitive = short.class;
    } else if (Float.class == wrapper) {
      primitive = float.class;
    } else if (Byte.class == wrapper) {
      primitive = byte.class;
    } else if (Character.class == wrapper) {
      primitive = char.class;
    } else {
      throw new IllegalArgumentException("The class is not a primitive wrapper type: " + wrapper);
    return primitive;

2.1.Data Type Introduction
2.1.1.The Primitive Types
2.1.2.Size for Java's Primitive Types
2.1.3.Default values for primitives and references
2.1.5.Surprise! Java lets you overflow
2.1.6.Wrapping a Primitive Type in a Wrapper Object: boolean, byte, char, short, int, long, float, double
2.1.7.Print the limits of primitive types (e.g. byte, short, int ...) in Java
2.1.8.Get the minimum and maximum value of a primitive data types
2.1.9.Shows default initial values
2.1.10.Primitive utilities
2.1.11.Return primitive type the passed in wrapper type corresponds to