Scala String lastIndexof()用法及代碼示例

字符串是存儲字符序列的不可變集合。

字符串 lastIndexOf() 方法

lastIndexOf() 方法用於獲取子字符串最後一次出現的索引，該子字符串作為參數傳遞給調用字符串中的方法。

用法:

string_Name.lastIndexOf(search_subString)

參數：該方法接受字符串類型的單個參數。它是要找到其出現的子串。

返回值：它返回一個整數值，它是字符串中子字符串最後一次出現的索引。

範例1：當子串隻出現一次時

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 )
    }
}

輸出：

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

範例2：當子串出現多次時

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 )
    }
}

輸出：

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

範例3：當沒有出現子串時

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 )
    }
}

輸出：

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