groovy学习3-语法学习
贴段练习代码，基本上包含了groovy强大的一些特性和语法
代码
package basic
/*
*
* @author <a href="mailto:czy88840616@gmail.com">czy</a>
* @since 2010-3-27 15:13:48
*
*/
println
"
helloworld
"
println
"
-----
"
//
loop
for
(i
in
0
..
2
)
println i
println
"
-----
"
//
upto
0
.upto(
2
) {print
"
$it
"
}
println
"
\n-----
"
//
times
3
.times {print
"
$it
"
}
println
"
\n-----
"
//
step
0
.step (
10
,
2
) {print
"
$it
"
}
println
"
\n-----
"
//
系统运行
println
"
ping
"
.execute().text
println
"
-----
"
println
"
ping
"
.execute().getClass().name
println
"
-----
"
println
"
cmd /C dir
"
.execute().text
println
"
-----
"
//
?.操作符
def foo(str){
str
?
.reverse()
}
println foo(
'
evil
'
)
println foo(
null
)
println
"
-----
"
//
exception
def openFile(fileName) {
new
FileInputStream(fileName)
}
try
{
openFile
"
xxxx.txt
"
}
catch
(e){
println
"
file not found:
"
+
e
}
println
"
-----
"
//
字符串条件判断-null
str
=
"
hello
"
if
(str) println str
println
"
-----
"
//
集合类型默认条件判断 null or empty
lst0
=
null
println lst0
?
'
lst0 true
'
:
'
lst0 false
'
lst1
=
[
1
,
2
,
3
]
println lst1
?
'
lst1 true
'
:
'
lst1 false
'
lst2
=
[]
println lst2
?
'
lst2 true
'
:
'
lst2 false
'
println
"
-----
"
//
<<操作符
lst
=
[
'
hello
'
]
lst
<<
'
there
'
println lst
println
"
-----
"
//
运算符重载
class ComplexNumber {
def real, imaginary
def plus(other) {
new
ComplexNumber(real: real
+
other.real, imaginary: imaginary
+
other.imaginary)
}
String toString() {
"
$real ${imaginary > 0 ? '+' : ''} ${imaginary}i
"
}
}
c1
=
new
ComplexNumber(real:
1
, imaginary:
2
)
c2
=
new
ComplexNumber(real:
4
, imaginary:
1
)
println c1
+
c2
println
"
------
"
//
return
def isPalindrome(str) { str
==
str.reverse() }
println
"
mom is palindrome? ${isPalindrome('mom')}
"
println
"
-----
"
//
== and is()
str1
=
'
hello
'
str2
=
str1
str3
=
new
String(
'
hello
'
)
str4
=
'
Hello
'
println
"
str1 == str2: ${str1 == str2}
"
println
"
str1 == str3: ${str1 == str3}
"
println
"
str1 == str4: ${str1 == str4}
"
println
"
str1.is(str2): ${str1.is(str2)}
"
println
"
str1.is(str3): ${str1.is(str3)}
"
println
"
str1.is(str4): ${str1.is(str4)}
"
println
"
-----
"
//
不可以省略；
class Semi {
def val
=
3
;
{
println
"
Instance Initializer called...
"
}
}
println
new
Semi()
println
"
-----
"
//
array
int
[] arr
=
[
1
,
2
,
3
,
4
,
5
]
println arr
println
"
class is
"
+
arr.getClass().name
println
"
-----
"
//
dynmic
def takeHelp(helper) {
//
...
helper.helpMoveThings()
//
...
}
class Man {
void
helpMoveThings() {
//
...
println
"
Man's helping
"
}
//
...
}
class Woman {
void
helpMoveThings() {
//
...
println
"
Woman's helping
"
}
//
...
}
class Elephant {
void
helpMoveThings() {
//
...
println
"
Elephant's helping
"
}
void
eatSugarcane() {
//
...
println
"
I love sugarcanes...
"
}
//
...
}
takeHelp(
new
Man())
takeHelp(
new
Woman())
takeHelp(
new
Elephant())
println
"
-----
"
//
clouse
def pickEven(n, block) {
for
(
int
i
=
2
; i
<=
n; i
+=
2
) {
block(i)
}
}
pickEven(
10
) { evenNumber
->
println evenNumber }
pickEven(
10
, { println it })
total
=
0
pickEven(
10
) { total
+=
it }
println
"
Sum of even numbers from 1 to 10 is ${total}
"
product
=
1
pickEven(
10
) { product
*=
it }
println
"
Product of even numbers from 1 to 10 is ${product}
"
//
闭包就是一个拥有参数的函数被绑定到上下文环境中来运行。