indexOf查找String中所有出现的单词

Question

我正在尝试使用indexOf来查找句子中所有出现的字符'the'.例如,如果句子是"我去那里的另一天",它应该返回3.

我能够做到这一点,直到它找到第一个索引,但我不确定如何编写循环.我最初有一个搜索整个字符串的for循环,但它返回的是完整的字符串字符长度,而不是我指定字符的出现次数.如何编写一个可以找到所有单词出现的循环？谢谢.

import java.util.Scanner;

public class TheFinder
{
    public static void main (String[] args)
    {
        String theString = "";
        Scanner enter = new Scanner(System.in);

        System.out.println("Please enter a sentence: ");
        theString = enter.nextLine();
        int counter2 = 0;
        theString.indexOf("the");

        if (theString.indexOf("the")!= -1)
        counter2++;



        System.out.printf("The characters 'the' were found %d times", counter2);
        System.out.println();

        System.out.println("This was programmed by -----");

Answer 1

您可以跟踪索引:

int index = theString.indexOf("the");
while(index >= 0) {
    index = theString.indexOf("the", index+1);
    counter2++;
}

Answer 2

你采取了一种复杂的方法.试试这个:

int count = str.split("the").length - 1;

如果你绝对必须使用indexOf():

str = str.toLowerCase();
int count = 0;
for (int i = str.indexOf("the"); i >= 0; i = str.indexOf("the", i + 1))
    count++;