public class DogTester { public static void main(String[] args) { Dog d1 = new Dog(); Dog d2 = new Dog(); name = "Charles"; } }
public class DogTester { public static void main(String[] args) { Dog d1 = new Dog(); Dog d2 = new Dog(); d1.name = "Charles"; } }
Data type | Default value |
---|---|
int |
0 |
double |
0.0 |
boolean |
false |
String , Scanner , Random , Dog ,... |
null |
What will d1
's instance variables contain? And d2
's?
class Dog { String name; int age; String breed = "Mongrel"; public void setName(String s) { name = s; } // etc. }
class DogTester { public static void main(String[] args) { Dog d1 = new Dog(); Dog d2 = new Dog(); d2.setBreed("Colombian Drug Lord"); // etc. } }
public static void main(String[] args) { Dog d1 = new Dog(); d1.setName("Charles"); d1.setAge(2); d1.setBreed("Charlywawa"); // etc. }
public static void main(String[] args) { Dog d1 = new Dog("Charles", 2, "Charlywawa"); // etc. }
public Dog(String s1, int n, String s2) { name = s1; age = n; breed = s2; }
new
Dog d1 = new Dog();
What will d1
's instance variables contain? And d2
's?
class Dog { String name; int age; String breed; public Dog(String s1, int n, String s2) { name = s1; age = n; breed= s2; } public void setName(String s) { name = s; } // etc. }
class DogTester { public static void main(String[] args) { Dog d1 = new Dog("Charles", 2, "Charlywawa"); Dog d2 = new Dog("Colin", 7, "Colombian Drug Lord"); d1.setName("Charlie"); // etc. } }
Define a BankAccount
class
main
method belowclass BankAccountTester { public static void main(String[] args) { BankAccount ac1 = new BankAccount("Sir Hugh Jeegoh"); BankAccount ac2 = new BankAccount("UCC"); ac2.deposit(1000); System.out.println(ac2.getBalance()); ac1.withdraw(50); System.out.println(ac1.getNumTransactions()); System.out.println(ac1); } }
BankAccount
interfacepublic BankAccount(String s) public void deposit(int amount) public void withdraw(int amount) public int getBalance() public int getNumTransactions() public String toString()
BankAccount
class definitionclass BankAccount { String name; int balance; int numTransactions; public BankAccount(String s) { name = s; } public void deposit(int amount) { balance = balance + amount; numTransactions = numTransactions + 1; } public void withdraw(int amount) { balance = balance - amount; numTransactions = numTransactions + 1; } public int getBalance() { return balance; } public int getNumTransactions() { return numTransactions; } public String toString() { return "Account name: " + name + " Balance: " + balance + " Number of transcations: " + numTransactions; } }