Math.random（）没有正确返回

Question

我有这个代码，我想要随机返回字符串，因此每次都会返回一个不同的字符串。它的工作原理罚款

words = sentenceStore[rnd.nextInt(sentenceStore.length)]; 

，但试图利用数学类的方法，它只是返回每次

words = sentenceStore[(int)Math.random() * sentenceStore.length]; 

谁能帮助索引0的字符串？

WordBank.java（无主此方法）：

import java.util.Random; 

public class WordBank { 

    private String [] sentenceStore; 

    public String getSentence (String words) { 

     String [] sentenceStore = new String [5]; //i'll store 5 sentences here for now. 

     sentenceStore[0] = "Hello how are you doing"; 
     sentenceStore[1] = "What do you want eh"; 
     sentenceStore[2] = "Hello can i help you"; 
     sentenceStore[3] = "You are so incredibly pretty"; 
     sentenceStore[4] = "What was that you said"; 

     Random rnd = new Random(); 

     words = sentenceStore[rnd.nextInt(sentenceStore.length)]; 

     //words = sentenceStore[(int)Math.random() * sentenceStore.length]; 

     return words; 
    } 
} 

Answer 1

你必须投整件事int，不仅Math.random()

(int)Math.random()总是返回0，然后你sentenceStore.length乘以0，这也会导致0。

使用

words = sentenceStore[(int) (Math.random() * sentenceStore.length)];