ThreadLocal.java

package java.lang;

public class ThreadLocal<T> {

  private T object;
  
  protected T initialValue() {
    return null;
  }
  
  public T get() {
    if(object == null) {
      object = initialValue();
    }
    return object;
  }
  
  public void set(T value) {
    object = value;
  }
}