Does Java support default parameter values?

java methods parameters overloading default-parameters
gnavi picture gnavi · Jun 15, 2009 · Viewed 1.3M times · Source

I came across some Java code that had the following structure:

public MyParameterizedFunction(String param1, int param2)
{
    this(param1, param2, false);
}

public MyParameterizedFunction(String param1, int param2, boolean param3)
{
    //use all three parameters here
}

I know that in C++ I can assign a parameter a default value. For example:

void MyParameterizedFunction(String param1, int param2, bool param3=false);

Does Java support this kind of syntax? Are there any reasons why this two step syntax is preferable?

Answer

Kathy Van Stone picture Kathy Van Stone · Jun 15, 2009

No, the structure you found is how Java handles it (that is, with overloading instead of default parameters).

For constructors, See Effective Java: Programming Language Guide's Item 1 tip (Consider static factory methods instead of constructors) if the overloading is getting complicated. For other methods, renaming some cases or using a parameter object can help. This is when you have enough complexity that differentiating is difficult. A definite case is where you have to differentiate using the order of parameters, not just number and type.

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