我不斷收到方法調用預期錯誤。我不知道我能做什么。有沒有人知道我們如何在不改變它的情況下進行主要運行？嘗試了幾個小時不同的方法，但無法弄清楚。public class UnsignedInteger {  public static void main(String[] args){    UnsignedInteger three = new UnsignedInteger(3); // 3 is "autoboxed"    UnsignedInteger four = new UnsignedInteger(4); // 4 is "autoboxed"    UnsignedInteger sum = three.add(four);    System.out.println(sum); // Should print 7    try    {        UnsignedInteger broken = new UnsignedInteger(-1);    }    catch(IllegalArgumentException e)    {        System.out.println("Negative values are not allowed");     }int val;// This is the constructor. It should throw an IllegalArgumentException if a //negative value is passed inpublic UnsignedInteger(Integer value){   if(value<0){      throw new IllegalArgumentException("You have entered a negative number.");    val=value;   }}// This method will return the Integer that was passed in via the constructor.public Integer getRawInteger(){    return val;}// Return the sum of the value stored in this object with the object passed as a parameter (i.e., otherUint)// This should not mutate the state of our class.public UnsignedInteger add(UnsignedInteger otherUint){   return  getRawInteger(this.add(getRawInteger()));    }}