Scala String lastIndexof()用法及代码示例

字符串是存储字符序列的不可变集合。

字符串 lastIndexOf() 方法

lastIndexOf() 方法用于获取子字符串最后一次出现的索引，该子字符串作为参数传递给调用字符串中的方法。

用法:

string_Name.lastIndexOf(search_subString)

参数：该方法接受字符串类型的单个参数。它是要找到其出现的子串。

返回值：它返回一个整数值，它是字符串中子字符串最后一次出现的索引。

范例1：当子串只出现一次时

object MyClass {
    def main(args:Array[String]) {
        val myString = "includehelp"
        println("The string is '" + myString + "'")
        
        val lastIndex = myString.lastIndexOf("help")
        println("The last index of 'help' is " + lastIndex )
    }
}

输出：

The string is 'includehelp'
The last index of 'help' is 7

范例2：当子串出现多次时

object MyClass {
    def main(args:Array[String]) {
        val myString = "abaabcdfssabsa"
        println("The string is '" + myString + "'")
        
        val lastIndex = myString.lastIndexOf("ab")
        println("The last index of 'ab' is " + lastIndex )
    }
}

输出：

The string is 'abaabcdfssabsa'
The last index of 'ab' is 10

范例3：当没有出现子串时

object MyClass {
    def main(args:Array[String]) {
        val myString = "scala Programming Language"
        println("The string is '" + myString + "'")
        
        val lastIndex = myString.lastIndexOf("include")
        println("The last index of 'include' is " + lastIndex )
    }
}

输出：

The string is 'scala Programming Language'
The last index of 'include' is -1