Groovy错误笔记1

今天抽了一点时间学习了一下Groovy的类定义，感觉基本上跟java差不多，于是跟着pdf照抄了一段，谁知道报错了:

class Money {

????private int amount

????private String currency ???

????Money (amountValue,currencyValue) {

????????amount = amountValue

????????currency = currencyValue

????} ???

????boolean equals (Object other) {

????????if (null == other) return false

????????if (!(other instanceof Money)) return false

????????if (currency != other.currency) return false

????????if (amount != other.amount) return false

????????return true

????} ???

????int hashCode() {

????????amount.hashCode() + currency.hashCode()

????} ???

????Money plus (Money other) {

????????if (null == other) return null

????????if (other.currency != currency) {

????????????throw new IllegalArgumentException(

????????????????"cannot add $other.currency to $currency")

????????????return new Money(amount + other.amount,currency)

????????}

????}

}

def buck = new Money(1,'USD')

assert buck

assert buck == new Money(1,'USD')

assert buck + buck == new Money(2,'USD')

我们在类中重写了plus、hashCode、equals方法，运行以后报：

Exception thrown

Assertion failed:

assert buck + buck == new Money(2,'USD')

???????| ???| | ???| ?|

???????| ???| | ???| ?Money@14968

???????| ???| | ???false

???????| ???| Money@14967

???????| ???null

???????Money@14967sert buck + buck == new Money(2,0)">?

?

java.lang.IllegalArgumentException: bad position: 976

at javax.swing.text.JTextComponent.moveCaretPosition(JTextComponent.java:1551)

at javax.swing.text.JTextComponent$moveCaretPosition$5.call(Unknown Source)

at groovy.ui.Console.hyperlinkUpdate(Console.groovy:1333)

at javax.swing.JEditorPane.fireHyperlinkUpdate(JEditorPane.java:345)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

那就找错吧，测试发现plus方法写错了，没有返回值了，唉，将蓝色的那句话放到外面就行了，正确的写法

Money plus (Money other) {

????????if (null == other) return null

????????if (other.currency != currency) {

????????????throw new IllegalArgumentException(

????????????????"cannot add $other.currency to $currency") ?????????

????????}

?return new Money(amount + other.amount,currency)

?}