Java Data Type - 如何搜索字符串

We can get the index of a character or a string within another string 
using the indexOf() and lastIndexOf() methods. For example,


public class Main {
  public static void main(String[] args) {
    String str = new String("Apple");

    int index = str.indexOf('p'); // index will have a value of 1
    System.out.println(index);
    
    index = str.indexOf("pl"); // index will have a value of 2
    System.out.println(index);
    index = str.lastIndexOf('p'); // index will have a value of 2
    System.out.println(index);
    
    index = str.lastIndexOf("pl"); // index will have a value of 2
    System.out.println(index);
    
    index = str.indexOf("k"); // index will have a value of -1
    System.out.println(index);
  }
}