我是Java编程的初学者。 我知道这个特定邮件错误的主题数量,但我无法解决此问题。在下面的代码中,错误被指示在第23行。 我知道这个问题似乎与空引用有关,但我无法看到我的方法“Recommander”是不是将值分配给所有引用。如何解决线程“main”中的异常java.lang.NullPointerException?
公共类Recommander {
// predetermined array of series
private String[] serie= {"Friends S1","Friends S2",
"Friends S6","Friends S7", "Friends S8", "How I met your mother S1",
"How I met your mother S2","How I met your mother S3 ","Castle S3",
"Santa Clarita Diet S1", "Modern Family S1","Modern Family S2",
"Family Guy S6", "The Simpsons S5"};
// array of the purchases of one customer
private int[] profil ;
//number of profiles in the database
private int nbProfils = 10 ;
// array of all the profiles from the database and the series available
private int[][] records ;
// creation of an instance of the object Recommander
public Recommander() {
for (int k=0;k<=nbProfils-1; k++) {
for (int i=0; i<=serie.length-1;i++) {
records[k][i]= (int) (Math.random())*2 ;
}
}
}
// Display of the series available in store
public String affichageSerie() {
String Affichage = "" ;
for (int i = 0 ; i<=serie.length-1; i++) {
Affichage = Affichage + serie[i] + "\n" ;
}
return Affichage ;
}
}
请出示线,所以我们是不是所有的强制倒计时23线。第23行似乎只是有一个大括号,所以加倍你需要明确显示该行。 – Carcigenicate
您的记录变量未初始化,因此它是空引用,当您尝试在for循环中写入它时,我认为它是第23行。您必须使用类似'private int [] [ ] records = new int [nbprofiles] [serie.length];'。 –