Groovy学习笔记二 基本语法

groovy.lang.*;
groovy.util.*;
java.lang.*;
java.io.*;
java.math.BigDecimal;
java.math.BigInteger;
java.net.*;
java.util.*;

a=new Date()
a=1;
Date b=new Date();
b=2.0;

Exception thrown
org.codehaus.groovy.runtime.typehandling.GroovyCastException: Cannot cast object ‘2.0‘ with class ‘java.math.BigDecimal‘ to class ‘java.util.Date‘
 at ConsoleScript4.run(ConsoleScript4:4)

1. 绑定域，绑定域是脚本的全局作用域。
2. 本地域，本地域就是变量的作用域局限于声明它们的代码块。对于在脚本代码块内声明的变量（比如在脚本的顶部），如果是定义过的变量，其作用域就是定义它的本地域。

 String hello="Hello World";
    void printHello()
    {
        System.out.println(hello);
    }
    printHello();

Exception thrown
    groovy.lang.MissingPropertyException: No such property: hello for class: ConsoleScript6
   at ConsoleScript6.printHello(ConsoleScript6:4)
   at ConsoleScript6.run(ConsoleScript6:6)

jvmLanguages=["Java","Groovy","Scala","Clojure"];
println(jvmLanguages[0]);
println(jvmLanguages.size());
println(jvmLanguages[0..2])
println(jvmLanguages[-1])
jvmLanguages=[];
println(jvmLanguages);

Java
4
[Java, Groovy, Scala]
Clojure
[]

 jvmLanguages=["Java",2,"Scala",new Date()];
 println(jvmLanguages);

[Java, 2, Scala, Mon Jan 05 14:22:22 CST 2015]

languageRatings=[Java:100,Groovy:99,Clojure:"null"];
println(languageRatings["Java"]);
println(languageRatings.Clojure)
languageRatings["Clojure"]=75;
println(languageRatings["Clojure"]);
println(languageRatings);
languageRatings=[:];
println(languageRatings);

100
null
75
[Java:100, Groovy:99, Clojure:75]
[:]

1. ? ? ?语句结束处的分号；
2. ? ? 返回语句（return）；
3. ? ? 方法参数两边的括号；
4. ? ? public访问限定符。

 Demo demo=new Demo();
println(demo.doSomething());
public class Demo
{
     public Integer doSomething()
     {
          def x=1
          def y;def String z="Hello World"
          println "the doSomething method be invoked!"
          x=5
      }
}

the doSomething method be invoked!
5

Integer x=new Integer(2);
    Integer y=new Integer(2);
    Integer z=null;
    if(x==y)
    {
        println "x==y"
    }
    if(!x.is(y))
    {
        println "x is not y"
    }
    if(z.is(null))
    {
        println "z is null"
    }
    if(z==null)
    {
        println "z is null"
    }

x==y
x is not y
z is null
z is null

?