在本教程中，我们将学习以下四种使用索引值在Vector中搜索元素的方法。
1）public int indexOf(Object o)：返回Vector中第一次出现的对象o的索引。
2）public int indexOf(Object o, int startIndex)：返回此向量中第一次出现的对象o的索引，从startIndex（包括）开始向前搜索。
3）public int lastIndexOf(Object o)：返回Vector中最后一次出现的对象o的索引。
4）public int lastIndexOf(Object o, int startIndex)：它返回此向量中最后一次出现的指定元素的索引，从startIndex（包括）向后搜索。
示例
在这个例子中，我们使用了上面提到的所有四种方法来证明它们的工作原理。
import java.util.Vector;public class SearchVector { public static void main(String[] args) { // Create a Vector object Vector<String> vector = new Vector<String>(); //Add elements to Vector vector.add("Kate"); vector.add("Patt"); vector.add("Kluge"); vector.add("Karon"); vector.add("Patt"); vector.add("Monica"); vector.add("Patt"); //This would return the index of first occurrence int first_index = vector.indexOf("Patt"); System.out.println("First Occurrence of Patt at index: "+first_index); //This would return the index of last occurrence int last_index = vector.lastIndexOf("Patt"); System.out.println("Last Occurrence of Patt at index: "+last_index); //This would start search from index 2(inclusive) int after_index = vector.indexOf("Patt", 2); System.out.println("Occurrence after index 2: "+after_index); //This would search the element backward starting from index 6(inclusive) int before_index = vector.lastIndexOf("Patt", 6); System.out.println("Occurrence before index 6: "+before_index); } }
输出：
First Occurrence of Patt at index: 1Last Occurrence of Patt at index: 6Occurrence after index 2: 4Occurrence before index 6: 6
