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我的代码是这样的:
public class Main{
public static void main(String[] args){
WordGroup wordgroupOne= new WordGroup ("You can discover more about a person in an hour of play than in a year of conversation");
WordGroup wordgroupTwo= new WordGroup ( "When you play play hard when you work dont play at all");
String[] quoteOne = wordgroupOne.getWordArray();
String[] quoteTwo = wordgroupTwo.getWordArray();
for (String word : quoteOne){
System.out.println(word);
}
for (String word : quoteTwo){
System.out.println(word);
}
}
}
词组类:
public class WordGroup {
public String words;
public WordGroup (String getWords){
words = words.toLowerCase();
}
public String[] getWordArray(){
return words.split(" ");
}
}
它编译得很好，但是当我尝试运行它时，我收到错误 java.lang.NullPointerException 并突出显示“words = words.toLowerCase();”(我正在使用 blueJ) 是什么原因造成的？
当研究它说这个错误是当你试图在一个空集上操作但是 WordGroup 不是空的，因为它有一个在 Main 中定义的字符串。