java - 从数组中的关键字搜索字符串

Question

我不明白为什么这不起作用？我试图从字符串中的数组中找到关键字，并在控制台中打印数组的索引号。我已经尝试过使用和不使用 boolean 值“true”的“if”语句

public class Testing 
{
    public static void main(String[] args)
    {
    String[] keywords = new String[5];
    keywords[0] = "boat";
    keywords[1] = "car";
    String myString = "the banana car";

          for(int a = 0; a <= keywords.length; ++a)

          {

             if(myString.contains(keywords[a])== true)
                {

                System.out.println(myString.indexOf(keywords[a]));
                }
             else
                {
                System.out.println("Those keywords are not in that string"); 
                }

           }
     }
}

Answer 1

String[] keywords = new String[5];////////////here you have array with 5 element
    keywords[0] = "boat";
    keywords[1] = "car";
//////////you just full index 0 and index 1

然后你在 keywords 的长度上循环

for (int a = 0; a <keywords.length; a++) 
//////keywords.length=5 , index 0 and index 1 have a value but the other index is empty 

所以:

• 您需要填满关键字数组:

   keywords[0] = "boat";
   keywords[1] = "car";
   keywords[2] = //////////;
   keywords[3] = //////////;
   keywords[4] = ///////;
  

• 或者让长度=2:

  String[] keywords = new String[2];