Java索引超出界限錯誤

我遇到了索引超出我的程序界限的問題。底部方法中的for循環應該按照flightSeatingAmount（）方法中指定的次數運行。但是在運行程序測試時，我總是收到錯誤信息。有時在出錯之前我會得到一個或兩個輸出，而其他時候我沒有得到任何輸出，只是出現錯誤。這裏是我的代碼：Java索引超出界限錯誤

import java.io.FileNotFoundException; 
import java.io.PrintWriter; 

public class OLE1 { 

static String[] airports = {"LAX", "MSP", "FAR", "ATL", "ORD", "DFW", "DEN", "JFK", "SFO", "CLT", "LAS", "PHX", "IAH", "MIA", "PEK", "CAN", "HND", "HKG", "SIN", "LHR", "CDG", "LGW", "MUC", "FRA", "EDI"}; 
static final int numberOfEntries = 10000; 
static String[] firstNames = {"Isis", "Donnette", "Reyes", "Willis", "Kathy", "Elizbeth", "Long", "Jim", "Devorah", "Magda", "Maryetta", "Keturah", "Corrinne", "Shena", "Xiao", "Otha", "Hallie", "Pennie", "Dong", "Kristopher", "Eveline", "Ardella", "Tien", "Tianna", "Loren", "Many", "Anjelica", "Cecile", "Mae", "Jenae", "Sonya", "Dotty", "Florance", "Mittie", "Katia", "Nena", "Lu", "Janee", "Armando", "Leandro", "Claris", "Claudine", "Moriah", "Eddie", "Susan", "Rhoda", "Monnie", "Emelia", "Cory", "Ying"}; 
static String[] lastNames = {"Belva", "Nam", "Liz", "Jeanett", "Corine", "Abe", "Olga", "Olevia", "Ernestine", "Joanne", "Sharyn", "Heidi", "Zachariah", "Sylvester", "Luetta", "Stephaine", "Garrett", "Debby", "Judi", "Noe", "Maybelle", "Eldora", "Roseann", "Madge", "Glayds", "Eleonore", "Josephine", "Quincy", "Alyson", "Earlene", "Clementina", "Jeri", "Kristel", "Carrol", "Zona", "Eileen", "Margherita", "Joline", "Terence", "Christinia", "Eldon", "Arleen", "Aimee", "Chanda", "Carin", "Prudence", "Tanja", "Kathlene", "Kareen", "Geneva"}; 
static String[] middleInitial = {"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"}; 
static int day = (int)(Math.random() * 21); 

public static void main(String args[]) throws FileNotFoundException { 

    System.out.println("Welcome to the airplane program. This program will go ahead and create a list of all the passengers that have gone through 25 different airports."); 
    System.out.println("The list of the airports we keep track of are listed below\n"); 

    //for listing out the airport names 
    int count = 0; 
    for (int i = 0; i < 5; i++) { 
     System.out.print(airports[count]); 
     count++; 
     System.out.print(" | " + airports[count]); 
     count++; 
     System.out.print(" | " + airports[count]); 
     count++; 
     System.out.print(" | " + airports[count]); 
     count++; 
     System.out.println(" | " + airports[count]); 
     count++; 
    } 

    flightManifest(); 

} 

public static int flightSeatingAmount() { 
    int flight = (int)(50 + (Math.random() * 800)); 
    return flight; 
} 

public static String nameGenerator() { 
    String names = ""; 
    int firstAndLast = (int)(Math.random() * 50); 
    int initial = (int)(Math.random() * 26); 
    names = lastNames[firstAndLast] + "," + firstNames[firstAndLast] + "," + middleInitial[initial]; 
    return names; 
} 

public static int flightTimeIntervel() { 
    int timing[] = {15, 30, 45, 00}; 
    int randomTiming = (int)(Math.random() * 4); 
    return timing[randomTiming]; 
} 

public static int airportSelectionOne() { 
    int airportOne = (int)(Math.random() * 49); 
    return airportOne; 
} 

public static int airportSelectionTwo() { 
    int airportTwo = (int)(Math.random() * 49); 
    return airportTwo; 
} 

public static void flightManifest() throws FileNotFoundException { 

    System.out.println(flightSeatingAmount()); 
    for (int i = 0; i <= flightSeatingAmount(); i++) { 
     System.out.println(nameGenerator() + "," + "0" + "," + airports[airportSelectionOne()]); 
    } 

} 

}

這裏是輸出我得到：

Welcome to the airplane program. This program will go ahead and create a list of all   the passengers that have gone through 25 different airports. 
The list of the airports we keep track of are listed below 

LAX | MSP | FAR | ATL | ORD 
DFW | DEN | JFK | SFO | CLT 
LAS | PHX | IAH | MIA | PEK 
CAN | HND | HKG | SIN | LHR 
CDG | LGW | MUC | FRA | EDI 
843 
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 45 
    at OLE1.flightManifest(OLE1.java:70) 
    at OLE1.main(OLE1.java:33)

843是指循環多少次應該執行。

來源

2014-02-06 user1881401

您的機場選擇一個返回45.機場數組中沒有46個機場。這意味着你很快超過了數組的末尾，這是非法的。改變你的函數，以便它不會返回比數組大的數字。提示：您可以通過airports.length

來源

2014-02-06 03:01:55

這個錯誤完全忘了。我甚至懶得去看那裏。謝謝你的幫助！ – user1881401

你用這個循環有問題告訴數組的大小：

for (int i = 0; i <= flightSeatingAmount(); i++) { 
     System.out.println(nameGenerator() + "," + "0" + "," + airports[airportSelectionOne()]); 
    }

您在方法flightSeatingAmount()產生一個隨機數也可能是zero，然後您嘗試初始化該大小的數組。但是，您必須檢查airportSelectionOne()是否也是隨機分配，是否在大小的範圍內。

來源

2014-02-06 03:02:56 Prince

將以下代碼更改爲具有正確大小的數組。

int airportOne = (int)(Math.random() * [size of airport array - 1]);

來源

2014-02-06 03:03:20

public static void flightManifest() throws FileNotFoundException { 

    System.out.println(flightSeatingAmount()); 
    for (int i = 0; i <= flightSeatingAmount(); i++) { 

//GOOD INFORMATION!!! 
System.out.println("airportSelectionOne()=" + airportSelectionOne() + ", airports.length=" + airports.length + ""); 

     System.out.println(nameGenerator() + "," + "0" + "," + airports[airportSelectionOne()]); 
    }  
}

那的System.out.println我在上面的函數中添加的是相當發人深省......

來源

2014-02-06 03:05:42 aliteralmind

Java索引超出界限錯誤

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