1、(Wrapper Class) Java (is-a)Number MIN_VALUE MAX_VALUE1- Integer new Integer(3) Integer ,valueOf Integer valueOf(int i) Integer valueOf(String s)valueOf(String s, int radix) 10 s IntegerInteger x = Integer.valueOf(3); IntegerInteger x = Integer.valueOf(10);int z1 = x.intValue(); /Integer-intlong z2 =
2、 x.longValue() /Integer-long1-/ 10 10 int 10int x = Integer.parseInt(10);/ 16 15int y = Integer.parseInt(F, 16); / int 10 10String z = Integer.toString(10); / 255 16String a = Integer.toHexString(255);2- Integer.MAX_VALUE Integer.MIN_VALUEint0 x80000000 0 x7fffffff DoublePOSITIVE_INFINITY NEGATIVE_I
3、NFINITYcompare(double d1, double d2) /double Integer JDK3- Integer(int ) (Autoboxing) 20Integer (Unboxing) o Integer30Math java.lang MathMath.sqrt(4); / cos sin abs cell floor min maxroundMath.random()/ 0.0,1.0) doubleRandommax min JDK MathMath.E /Math.PI / Boolean bool Character(char )isLetter /isDigit /isWhitespace /isUpperCase isLowerCase /toUpperCase toLowerCase /toSting /
