groovy與java比較

默認導入如下包

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

常見錯誤

• ==表明equals()
• in是一個關鍵字
• 聲明數組用[ ]
• for (int i=0; i < len; i++) {...}通常用如下簡寫
  • for (i in 0..len-1) {...}
  • for (i in 0..<len) {...}
  • len.times {...}

注意事項

• 分號是可選的。多條語句寫在一行時必須用分號
• return關鍵字是可選的
• static methods內必須使用this關鍵字
• 方法和類默認是pubilc
• protected同java
• 不支持內部類，可用閉包(closures）代替
• 不會檢查方法throws的異常，there is no difference between checked and unchecked exceptions.
• 沒有定義的成員和類型不編譯是不會報錯，參見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