Groovy In Action 笔记 (3) -- 基本数据类型

Groovy中所有类型均为引用类型。即使是Java中的８种Primitive Type,groovy中背后使用的都是对应的包装类。没有boxing,unboxing操作.

一下为一些基本类型操作

//Integer
def age = 10

println("age++ " + (age++)) // age++ 10, 先输出，再自增
assert age == 11

println("++age " + (++age)) // ++age 12，先自增，再输出

assert age == 12

assert 12.toString() == age.toString() // 可直接对常量使用方法
assert 12.8.toInteger() == 12 // 可直接对常量使用方法

//float
def weight_f = 1.2f
def weight_F = 1.2F
assert weight_f.class.name == Float.name
assert weight_F.class.name == Float.name

//double
def weight_d = 1.2d
def weight_D = 1.2D

assert weight_d.class.name == Double.name
assert weight_D.class.name == Double.name

//long
def meter_l = 1000L
assert meter_l.class.name == Long.name

//bigInteger
def universe_age_g = 1000G
assert universe_age_g.class.name == BigInteger.name

//bigDecimal
def decimal_default = 1.2  ///注意默认为　bigDecimal类型，和Java不同
def decimal_b= 1.2g

assert decimal_default.class.name == BigDecimal.name
assert decimal_b.class.name == BigDecimal.name


// operators
def compare_a = 20
def compare_b = 10

assert compare_a > compare_b
assert compare_b < compare_a
assert (compare_a <=> compare_b) == 1  // <=> 相当于　compareTo函数

assert 5 / 2 == 2.5 //默认bigDecimal
assert 3 % 2 == 1 //取余数 a.mod(b)
assert 5.intdiv(2) == 2 //整除

assert compare_a >> 2 == 5 //右移两位，相当于除以４
assert compare_a << 2 == 80 //左移两位，相当于乘以４


//动态数据类型变化 --- Groovy中所有类型均为　引用类型。　即使是Java中的８种Primitive Type,groovy中背后使用的都是对应的包装类。没有boxing,unboxing操作
def type_variant = 100
assert type_variant.class.name == Integer.name

type_variant = 100f
assert type_variant.class.name == Float.name

type_variant = 100d
assert type_variant.class.name == Double.name

type_variant = "STRING"
assert type_variant.class.name == String.name