我得到這個空指針異常:Java代碼生成一個空指針異常
java.lang.NullPointerException
at ATM.isItValid(ATM.java:64)
at ATM.displayGreeting(ATM.java:59)
at Bank.runATM(Bank.java:90)
at Bank.displayBank(Bank.java:109)
at Bank.addAccount(Bank.java:52)
at Bank.displayBank(Bank.java:105)
at Bank.addAccount(Bank.java:52)
at Bank.displayBank(Bank.java:105)
at BankDriver.main(BankDriver.java:6)
從這個代碼:
public void displayGreeting() {
clearScreen();
System.out.println("Welcome to Bob's Friendly Bank\n");
do {
System.out.print("Enter card number: ");
currentCard = input.next();
System.out.print("Enter PIN: ");
currentPIN = input.next();
System.out.println(currentCard + currentPIN);
} while (!(isItValid()));
}
public boolean isItValid(){
boolean answer = false;
if(theBank.validCard(currentCard, currentPIN)) //Exception thrown here.
answer = true;
return answer;
}
有什麼不對?
刪除不必要的代碼並指出錯誤被拋出的位置。 – ogzd 2013-02-11 21:25:20
上一個問題:http://stackoverflow.com/questions/14819712/java-lang-nullpointerexception-with-arraylist – 2013-02-11 21:26:58
使用調試器或舊學校*品脫* - 調試,以找到您嘗試呼叫的'null'一個方法。 – MrSmith42 2013-02-11 21:28:32