indexOf(int ch)是Java中的String方法,用于获取字符串中指定字符的索引。
如果该字符存在于字符串中,则返回该字符首次出现的索引,如果该字符不存在于字符串中,则返回-1。
语法:
int str_object.indexOf(int chr);
这里,
str_object是主字符串的对象,我们必须在其中找到给定字符的索引。
chr是要在字符串中找到的字符。
它接受一个字符并返回其首次出现的索引;如果字符串中不存在该字符,则返回-1。
示例
Input: String str = "NHOOO" Function call: str.indexOf('H') Output: 7 Input: String str = "NHOOO" Function call: str.indexOf('W') Output: -1
Java代码演示String.indexOf()方法的示例
public class Main { public static void main(String[] args) { String str = "NHOOO"; char ch; int index; ch = 'H'; index = str.indexOf(ch); if(index != -1) System.out.println(ch + " is found at " + index + " position."); else System.out.println(ch + " does not found."); ch = 'e'; index = str.indexOf(ch); if(index != -1) System.out.println(ch + " is found at " + index + " position."); else System.out.println(ch + " does not found."); ch = 'W'; index = str.indexOf(ch); if(index != -1) System.out.println(ch + " is found at " + index + " position."); else System.out.println(ch + " does not found."); } }
输出结果
H is found at 7 position. e is found at 6 position. W does not found.