public class TestBoolean { static Boolean a; static boolean b; public static void main(String[] args) { int x = 0; int y =0; //此处先用b,则输出x=1,若用a,则报java.lang.NullPointerException if(a){ x++; System.out.println("x="x); }else { y++; System.out.println("y="y); } } }
由此可见Boolean定义的变量是没有默认初始值的!
而boolean定义的变量的默认初始值是false!