java construct method definition

What is this called? This is a 开发者_开发问答constructor from the Bits class from JBitTorrent API. It is perfectly valid:

public Bits and(Bits b){ /* something */ }

But there's a space in the method name. So whas is this called? I thought is "java multimethod" but it's not.

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It's not a constructor, it's a regular Java method.

The first Bits is the return type, and and is the method name.

If it were a constructor, it would not have a return type, and the name would be the name of the class it is constructing.

The method may be constructing a new Bits instance and returning it, but it's still a method.

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It's not a constructor and there's no space in the method name.

The method is called and, it takes a Bits object as the argument and it returns a Bits object.

It's a normal method with there's no particular name for this (from the language perspective).

It's a common pattern, usually used for immutable objects: instead of modifying the object on which the method is called, a new object is created with the modified state (this can also be done on mutable objects, but is more common with immutable ones).

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Where do you think you see a space in the method name?

public Bits and(Bits b){ //something }

It is a public method named and that returns a Bits object, and that takes a Bits object as an argument (with the argument variable named b).

It is not a constructor, just a regular method.

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but there's a space in the method name

No there isn't. The method name is "and". Bits is the return type!

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There's not a space in the method, the method name is "and".

• public - modifier
• Bits - return value
• and - method name
• Bits b - a parameter b of type Bits

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Usually used in a Builder pattern (e.g. StringBuilder) where fields/operations are provided to create a fully constructed object.

The public Bits and(Bits b) {...} is not a constructor but method that requires a Bits b in order to change the state of the current internal bits (ANDed).

The implementation would be of this effect.

public Bits and(Bits b) {
    this.doAnd(b);

    //Now that our internal bits are ANDed with bits B, return our changed state
    return this;
}