Boolean

"Hi, Amigo!"

"Hi, Kim."

"I'm going to tell you about the Boolean type. It's a wrapper for the boolean type, and it's as easy as pie. Here's some simplified code from the Boolean class:"

class Boolean
{
 public static final Boolean TRUE = new Boolean(true);
 public static final Boolean FALSE = new Boolean(false);

 private final boolean value;

 public Boolean(boolean value)
 {
  this.value = value;
 }

 public boolean booleanValue()
 {
  return value;
 }

 public static Boolean valueOf(boolean b)
 {
  return (b ? TRUE : FALSE);
 }
}

"In other words, the class is simply a wrapper for the boolean type."

"Yep. And it has two constants (TRUE and FALSE), which are counterparts of the primitive values true and false."

"It also handles autoboxing like a champ:"

Boolean a = true;
Boolean b = true;
Boolean c = false;
boolean d = a;

Boolean a = Boolean.valueOf(true);
Boolean b = Boolean.valueOf(true);
Boolean c = Boolean.valueOf(false);
boolean d = a.booleanValue();

"And here's how comparisons between boolean and Boolean types work:"

boolean a = true;
Boolean b = true; //Will be equal to Boolean.TRUE
Boolean c = true; //Will be equal to Boolean.TRUE

a == b; //true (comparison based on primitive value)
a == c; //true (comparison based on primitive value)
b == c; //true (comparison based on references, but they point to the same object)

"If you really need to create an independent Boolean object, you must create it explicitly:

boolean a = true;
Boolean b = new Boolean(true); //A new Boolean object
Boolean c = true; //Will be equal to Boolean.TRUE

a == b; //true (comparison based on primitive value)
a == c; //true (comparison based on primitive value)
b == c; //false (comparison based on references; they point to different objects)

"I think that's all for now."

"Yeah, your lessons are shorter than Bilaabo's."

"So, can I use Boolean inside an if condition?"

Boolean less = (2 < 3);
if (less)
{
….
}

"Yes, just don't forget that if less is null, then a NullPointerException will be thrown."

"Yep, I already get that. I just don't keep it all in my head all the time."