Java - String indexOf() Method_JAVA_编程开发_程序员俱乐部

源地址：http://www.tutorialspoint.com/java/java_string_indexof.htm

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Description:

This method has following different variants:

class="list">

• public int indexOf(int ch):?Returns the index within this string of the first occurrence of the specified character or -1 if the character does not occur.

• public int indexOf(int ch, int fromIndex):?Returns the index within this string of the first occurrence of the specified character, starting the search at the specified index or -1 if the character does not occur.

• int indexOf(String str):?Returns the index within this string of the first occurrence of the specified substring. If it does not occur as a substring, -1 is returned.

• int indexOf(String str, int fromIndex):?Returns the index within this string of the first occurrence of the specified substring, starting at the specified index. If it does not occur, -1 is returned.

Syntax:

Here is the syntax of this method:

public int indexOf(int ch )

or

public int indexOf(int ch, int fromIndex)

or

int indexOf(String str)

or

int indexOf(String str, int fromIndex)

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Parameters:

Here is the detail of parameters:

• ch?-- a character.

• fromIndex?-- the index to start the search from.

• str?-- a string.

Return Value:

• See the description.

Example:

import java.io.*;

public class Test {

   public static void main(String args[]) {
      String Str = new String("Welcome to Tutorialspoint.com");
      String SubStr1 = new String("Tutorials");
      String SubStr2 = new String("Sutorials");

      System.out.print("Found Index :" );
      System.out.println(Str.indexOf( 'o' ));
      System.out.print("Found Index :" );
      System.out.println(Str.indexOf( 'o', 5 ));
      System.out.print("Found Index :" );
      System.out.println( Str.indexOf( SubStr1 ));
      System.out.print("Found Index :" );
      System.out.println( Str.indexOf( SubStr1, 15 ));
      System.out.print("Found Index :" );
      System.out.println(Str.indexOf( SubStr2 ));
   }
}

?This produces the following result:

Found Index :4
Found Index :9
Found Index :11
Found Index :-1
Found Index :-1

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