groovy与java比较

默认导入如下包

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

常见错误

• ==表明equals()
• in是一个关键字
• 声明数组用[ ]
• for (int i=0; i < len; i++) {...}通常用如下简写
  • for (i in 0..len-1) {...}
  • for (i in 0..<len) {...}
  • len.times {...}

注意事项

• 分号是可选的。多条语句写在一行时必须用分号
• return关键字是可选的
• static methods内必须使用this关键字
• 方法和类默认是pubilc
• protected同java
• 不支持内部类，可用闭包(closures）代替
• 不会检查方法throws的异常，there is no difference between checked and unchecked exceptions.
• 没有定义的成员和类型不编译是不会报错，参见Runtime vs Compile time, Static vs Dynamic.

New features added to Groovy not available in Java

• Closures
• native syntax for lists and maps
• GroovyMarkup and GPath support
• native support for regular expressions
• polymorphic iteration and powerful switch statement
• dynamic and static typing is supported - so you can omit the type declarations on methods, fields and variables
• you can embed expressions inside strings
• lots of new helper methods added to the JDK
• simpler syntax for writing beans for both properties and adding event listeners
• safe navigation using the ?. operator, e.g. "variable?.field" and "variable?.method()" - no more nested ifs to check for null clogging up your code