这个程序一直在21行和99行抛出空指针异常，谁知道怎么回事？

Question

package overlaod;//import java.awt.print.Book;public class OverloadTest { private Book[ ] booksList;    void OverloadTest(Book[] booksList ){ Book booskList[] = { new Book("郁达夫随笔：伤感旅行","郁达夫","北京大学出版社",38.0f), new Book("教育法学","李晓燕 主编","高等教育出版社",23.9f), new Book("普通化学原理与应用","毕德乐","高等教育出版社",89.0f), new Book("机关工会工作指南","郭红美","中国工人出版社",36.0f) }; this.booksList = booksList; } OverloadTest(Book ... book){ booksList = book; } void getBookInfo(){ System.out.println("全部图书："); //System.out.println(booksList); for(int i = 0; i< booksList.length; i++){ System.out.println("\t"+(i+1)+"."+booksList[i].title+                     "\t"+booksList[i].author+                     "\t"+booksList[i].publisher+                     "\t"+booksList[i].price); } } void getBookInfo(float price){ System.out.println("价格为“"+price+"”的图书"); int m = 1; for(int i = 0; i< booksList.length; i++){ if(booksList[i].price == price){ System.out.println("\t"+m+"."+booksList[i].title+                     "\t"+booksList[i].author+                     "\t"+booksList[i].publisher); m++; } } } void getBookInfo(String publisher){ System.out.println("出版社为“"+publisher+"”的图书：");  int m = 1; for(int i = 0; i < booksList.length; i++){ if(booksList[i].publisher == publisher){ System.out.println("\t"+m+"."+booksList[i].title+                     "\t"+booksList[i].author+                     "\t"+booksList[i].publisher); m++; } } } void getBookInfo(float price, String publisher){ System.out.println("价格为“"+price+"”且出版社为“"+publisher+"”的图书："); int m = 1; for(int i = 0; i < booksList.length; i++){ if((booksList[i].price == price) & (booksList[i].publisher == publisher)){ System.out.println("\t"+m+"."+booksList[i].title+                     "\t"+booksList[i].author); m++; } } } void getBookInfo(String publisher,float price){ System.out.println("出版社为“"+price+"”且价格为“"+publisher+"”的图书："); int m = 1; for(int i = 0; i < booksList.length; i++){ if((booksList[i].publisher == publisher) & (booksList[i].price == price)){ System.out.println("\t"+m+"."+booksList[i].title+                     "\t"+booksList[i].author); m++; } } } void getBookInfo(float...price) { String s =""; int  m = 1; for(float bookPrice:price){ s = s + bookPrice + " "; } System.out.println("价格为“"+s.trim( )+"”的图书："); for(float bookPrice:price){ int i = 0; while(i < booksList.length){ if(bookPrice == booksList[i].price){ System.out.println("\t"+(i+1)+"."+booksList[i].title+                     "\t"+booksList[i].author+                     "\t"+booksList[i].publisher+                     "\t"+booksList[i].price); } i++; } } } //void getBookInfo(float[] price){}//方法重复 public static void main(String[ ] args){ OverloadTest  overloadTest = new OverloadTest( ); overloadTest.getBookInfo( ); overloadTest.getBookInfo(36f); overloadTest.getBookInfo("高等教育出版社"); overloadTest.getBookInfo(89f,"高等教育出版社"); overloadTest.getBookInfo("北京大学出版社",38f); overloadTest.getBookInfo(36f,28f); overloadTest = null; overloadTest = new OverloadTest( new Book("艺术批评学","陈汉青","北京大学出版社",28.0f), new Book("工程力学","范钦山","高等教育出版社",71.0f)); overloadTest.getBookInfo( ); }}class Book{ String title; String author; String publisher; float price; Book(String title, String author, String publisher, float price){ this.title = title; this.author = author; this.publisher = publisher; this.price = price; }}

Answer 1

没发现哪里报空指针