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当我编码时,我在ObjectArray.main(ObjectArray.java:24)上得到一个异常作为“线程中的异常”main“java.lang.NullPointerException”_Java_Arrays_Eclipse_Nullpointerexception - Fatal编程技术网

当我编码时,我在ObjectArray.main(ObjectArray.java:24)上得到一个异常作为“线程中的异常”main“java.lang.NullPointerException”

当我编码时,我在ObjectArray.main(ObjectArray.java:24)上得到一个异常作为“线程中的异常”main“java.lang.NullPointerException”,java,arrays,eclipse,nullpointerexception,Java,Arrays,Eclipse,Nullpointerexception,当我在eclipse中执行以下代码时: class Account { int a, b; public void setData(int c, int d) { a=c; b=d; } public void showData() { System.out.println("Value of a: "+a); System.out.println("Value of b: "+b); } } public class Object

当我在eclipse中执行以下代码时:

class Account
{
  int a, b;
  public void setData(int c, int d)
  {
    a=c;
    b=d;
  }

  public void showData()
  {
    System.out.println("Value of a: "+a);
    System.out.println("Value of b: "+b);
  }
}

public class ObjectArray 
{
  public static void main(String args[])
  {
    Account obj[] = new Account[2];
    //obj[0]=new Account();
    //obj[1]=new Account();
    obj[0].setData(1, 2);
    obj[1].setData(3, 4);
    System.out.println("For Array Element 0:");
    obj[0].showData();
    System.out.println("For Array Element 1:");
    obj[1].showData();
  }
}
我得到以下例外情况:

线程主java.lang.NullPointerException中出现异常 位于ObjectArray.mainObjectArray.java:24

请给我一个建议,为什么会发生这个错误

Account obj[] = new Account[2];
它将为“Account”类的2个对象分配内存。要初始化这些内存位置,您必须选择以下任一方式:

Account obj[] = {new Account(), new Account()};
obj[0]=new Account();
obj[1]=new Account();

因为你注释掉了初始化,这会阻止NPE?