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Java 代码给出NullPointerException_Java - Fatal编程技术网

Java 代码给出NullPointerException

Java 代码给出NullPointerException,java,Java,我已经上了五节课(如下所示)。当我运行代码时,它会给我“NullPointerException” 头等舱 public class PasPosition { boolean lessThanThirty; boolean ThirtyToFifty; boolean FiftyToHundred; public PasPosition(boolean value1, boolean value2, boolean value3) {

我已经上了五节课(如下所示)。当我运行代码时,它会给我“NullPointerException”

头等舱

public class PasPosition {

      boolean lessThanThirty;
      boolean ThirtyToFifty;
      boolean FiftyToHundred;

     public PasPosition(boolean value1, boolean value2, boolean value3)
     {
        lessThanThirty = value1;
        ThirtyToFifty = value2;
        FiftyToHundred = value3;

    }

}
二等舱

  public class CssPosition {

    boolean lessThanThirty;
    boolean ThirtyToFifty;
    boolean FiftyToHundred;
    public CssPosition(boolean value1,boolean value2, boolean value3)
    {
        lessThanThirty = value1;
        ThirtyToFifty = value2;
        FiftyToHundred = value3;
   }
 }
三等舱

  public class SiteData {

     PasPosition pas;
     CssPosition css;


  }
最后一节课

  public class Test {

    SiteData[] sitedata = new SiteData[2];

    public void test()
    {

        for(int i=0;i<sitedata.length;i++)
        {
            System.out.println(sitedata[i].css.FiftyToHundred);
            System.out.println(sitedata[i].css.ThirtyToFifty);
            System.out.println(sitedata[i].css.lessThanThirty);
            System.out.println();
        }
    }

  }
公共类测试{
SiteData[]SiteData=新站点数据[2];
公开无效测试()
{

对于(inti=0;i,似乎没有初始化对象

您必须知道,在java中,类中的对象不会自动初始化。您必须使用
new
运算符

public class SiteData {
    PasPosition pas=new PasPosition(false,false,false); 
    CssPosition css=new CssPosition(false,false,false);//use your own initial value
}

css
pas
何时初始化?请在javaapplication16.Test.Test(Test.java:21)的javaapplication16.main.main(main.java:25)的线程“main”java.lang.NullPointerException中粘贴NullPointerException.Exception的错误消息Java结果:1您已经声明了SiteData数组,但没有进行初始化,这就是您获得NullPointerException的原因。它仍然会给我相同的错误。以下是错误:javaapplication16.Test.Test中的线程“main”Java.lang.NullPointerException在javaapplication16.main.main(main.Java:25)中的异常Java结果:1@Bakhtawar请提供完整的Main.javaor,否则我将不知道第25行在哪里。我解决了问题…谢谢…在阅读了上面的一条评论后,我意识到我已经声明了数组,但没有初始化它。