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？
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;
}
}
慕粉23473495781回答
-
DaRKeViL
没发现哪里报空指针
随时随地看视频慕课网APP
相关分类
Java