Binary tree

Tree.java

class Tree {
  
  Holder initial;
  
  add(int value) {
    Holder object = initial;
    addToHolder(object);
  }
  
  private addToHolder(Holder object, int value) {
    if (object == null) {
      object = new Holder(value);
    } else {
      if (value > object.value) {
        addToHolder(object.greater);
      } else if (value < object.value) {
        addToHolder(object.less);
      }
    }
  }
  
  remove(int value) {
    removeFromHolder(initial);
  }
  
  private removeFromHolder(Holder) {
    ...
  }
  
  class Holder {
    int value;
    
    Holder(int value) {
      this.value = value;
    }
    
    Holder less;
    Holder greater;
  }
}