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[英]java.lang.ArrayIndexOutOfBoundsException: Index 0 out of bounds for length 0; why a[0][0] has ArrayIndexOutOfBoundsException problem?
[英]java.lang.ArrayIndexOutOfBoundsException: Index -1 out of bounds for length 7 on a binary search
我必須編寫一個程序來通過輸入“Prezzo”值來搜索“Nomi”的通訊員,但是當我進行二分搜索時,出現錯誤:
java.lang.ArrayIndexOutOfBoundsException:在二進制搜索中,長度為 7 的索引 -1 越界
這是代碼:
import java.io.*;
public class Blackfriday {
public static int ricercaBinaria(Double prezzi[], Double chiave) {
int inf = 0, sup = prezzi.length - 1;
while (inf <= sup) {
int med = (inf + sup) / 2;
if (prezzi[med] == chiave)
return med;
if (prezzi[med] < chiave)
inf = med + 1;
else
sup = med - 1;
}
return -1;
}
public static void main(String args[]) {
try {
InputStreamReader isr;
BufferedReader br;
double cerca;
isr = new InputStreamReader(System.in);// abilitato la lettura da tastiera
br = new BufferedReader(isr);// abilitato la lettura un rigo per volta
String nomi[] = { "picones", "vinile di Speranza", "Laurea", "King Mufasa", "Pentium Gold",
"Aethey Wind breaker ORO", "HeelCompletoSpaic1we" };
Double prezzi[] = { 2.0, 13.50, 23.0, 99.50, 120.0, 75.20, 999.99 };
System.out.println("Quanto vuoi spendere?");
String xStringa = br.readLine();// ricevo la digitazione in String
cerca = Double.parseDouble(xStringa);// Trasformo la String in double
System.out.println("Puoi comprare: " + nomi[ricercaBinaria(prezzi, cerca)]);
} catch (Exception e) {
System.out.println(e);
}
}
}
您的代碼至少有兩個問題。
ricercaBinaria
一個前提是底層數據數組是有序的。 您在測試中使用了無序數據ricercaBinaria
將返回給定參數 ( Double
) 在您的數組中所在的索引。 如果未找到,則返回-1
。 因此,在將其用作索引數組之前,您需要檢查返回的索引以驗證它確實為正值 - 否則該方法將失敗並出現您看到的異常這是一個功能代碼:
public class Blackfriday {
public static int ricercaBinaria(double prezzi[], Double chiave) {
int inf = 0, sup = prezzi.length - 1;
while (inf <= sup) {
int med = (inf + sup) / 2;
if (prezzi[med] == chiave)
return med;
if (prezzi[med] < chiave)
inf = med + 1;
else
sup = med - 1;
}
return -1;
}
public static void main(String args[]) {
try {
InputStreamReader isr;
BufferedReader br;
double cerca;
isr = new InputStreamReader(System.in);//abilitato la lettura da tastiera
br = new BufferedReader(isr);//abilitato la lettura un rigo per volta
String nomi[] = {"picones", "vinile di Speranza", "Laurea", "King Mufasa", "Pentium Gold", "Aethey Wind breaker ORO", "HeelCompletoSpaic1we"};
double prezzi[] = {2.0, 13.50, 23.0, 99.50, 120.0, 75.20, 999.99};
System.out.println("Quanto vuoi spendere?");
String xStringa = br.readLine();//ricevo la digitazione in String
cerca = Double.parseDouble(xStringa);//Trasformo la String in double
System.out.println("Puoi comprare: " + nomi[ricercaBinaria(prezzi, cerca)]);
} catch (Exception e) {
e.printStackTrace();
}
}//main
}//classe
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