java - 如何避免空指针错误

Question

我试图找出 2 个 arrayList 的元素是否匹配。但这段代码给了我错误 Exception in thread "AWT-EventQueue-0"java.lang.NullPointerException 因为某些元素为 null。

如何解决这个问题？

String level []={"High","High","High","High","High","High"};
ArrayList<Object> n = new ArrayList<Object>(Arrays.asList(level));

String choice []={null,"High","Low","High",null,"Medium"}; 
ArrayList<Object> m = new ArrayList<Object>(Arrays.asList(choice));

//Check if the two arrayList are identical
for(int i=0; i<m.size(); i++){
   if(!(m.get(i).equals(n.get(i)))){   
 result= true;
 break;
   } 
} 
    return  result;
}

Answer 1

只需使用 Arrays.equals，如下所示:

    String level []={"High","High","High","High","High","High"};

    String choice []={null,"High","Low","High",null,"Medium"}; 

    return Arrays.equals(level, choice);