function HaHa($a = "Test")
{
    print $a;
}

public void someFunction(int ttt = 5)
{
   // something
}

int someMethod() { return someMethod(42); }
int someMethod(int arg) { .... }

public int getScore(int score, Integer... bonus)
{
    if(bonus.length > 0)
    {
        return score + bonus[0];
    }
    else
    {
        return score;
    }
}

public void doSomething(boolean... arg1) {
    boolean MyArg1= (arg1.length >= 1) ? arg1: false;
}

public void methodA(A arg1) {  }
public void methodA( B arg2,) {  }
public void methodA(C arg3) {  }
public void methodA(A arg1, B arg2) {  }
public void methodA(A arg1, C arg3) {  }
public void methodA( B arg2, C arg3) {  }
public void methodA(A arg1, B arg2, C arg3) {  }

public static void main(String[] args)
{
    defaultParameter();
    defaultParameter(true);
}

public static void defaultParameter(Boolean ...gender)
{
    boolean genderBoolean  = false; // It the default value you want to give
    if(gender.length == 1)
    {
        genderBoolean = gender[0];  // Overrided Value
    }
    System.out.println(genderBoolean);
}

false
true

if (ttt == 0) ttt = 5;