diff --git a/core-java/src/main/java/com/baeldung/constructors/BankAccount.java b/core-java/src/main/java/com/baeldung/constructors/BankAccount.java new file mode 100644 index 0000000000..3d50e85245 --- /dev/null +++ b/core-java/src/main/java/com/baeldung/constructors/BankAccount.java @@ -0,0 +1,56 @@ +package com.baeldung.constructors; + +import java.time.LocalDateTime; + +class BankAccount { + String name; + LocalDateTime opened; + double balance; + + @Override + public String toString() { + return String.format("%s, %s, %f", this.name, this.opened.toString(), this.balance); + } + + public String getName() { + return name; + } + + public LocalDateTime getOpened() { + return opened; + } + + public double getBalance() { + return this.balance; + } +} + +class BankAccountEmptyConstructor extends BankAccount { + public BankAccountEmptyConstructor() { + this.name = ""; + this.opened = LocalDateTime.now(); + this.balance = 0.0d; + } +} + +class BankAccountParameterizedConstructor extends BankAccount { + public BankAccountParameterizedConstructor(String name, LocalDateTime opened, double balance) { + this.name = name; + this.opened = opened; + this.balance = balance; + } +} + +class BankAccountCopyConstructor extends BankAccount { + public BankAccountCopyConstructor(String name, LocalDateTime opened, double balance) { + this.name = name; + this.opened = opened; + this.balance = balance; + } + + public BankAccountCopyConstructor(BankAccount other) { + this.name = other.name; + this.opened = LocalDateTime.now(); + this.balance = 0.0f; + } +} diff --git a/core-java/src/main/java/com/baeldung/constructors/Transaction.java b/core-java/src/main/java/com/baeldung/constructors/Transaction.java new file mode 100644 index 0000000000..14704f507a --- /dev/null +++ b/core-java/src/main/java/com/baeldung/constructors/Transaction.java @@ -0,0 +1,25 @@ +package com.baeldung.constructors; + +import java.time.LocalDateTime; + +class Transaction { + final BankAccountEmptyConstructor bankAccount; + final LocalDateTime date; + final double amount; + + public Transaction(BankAccountEmptyConstructor account, LocalDateTime date, double amount) { + this.bankAccount = account; + this.date = date; + this.amount = amount; + } + + /* + * Compilation Error :'(, all final variables must be explicitly initialised. + * public Transaction() { + * } + */ + + public void invalidMethod() { + // this.amount = 102.03; // Results in a compiler error. You cannot change the value of a final variable. + } +} diff --git a/core-java/src/test/java/com/baeldung/constructors/ConstructorUnitTest.java b/core-java/src/test/java/com/baeldung/constructors/ConstructorUnitTest.java new file mode 100644 index 0000000000..2cd8832fbf --- /dev/null +++ b/core-java/src/test/java/com/baeldung/constructors/ConstructorUnitTest.java @@ -0,0 +1,53 @@ +package com.baeldung.constructors; + +import com.baeldung.constructors.*; + +import java.util.logging.Logger; +import java.time.LocalDateTime; +import java.time.Month; + +import org.junit.Test; +import static org.assertj.core.api.Assertions.assertThat; +import static org.assertj.core.api.Assertions.assertThatCode; +import static org.assertj.core.api.Assertions.assertThatThrownBy; + +public class ConstructorUnitTest { + final static Logger LOGGER = Logger.getLogger(ConstructorUnitTest.class.getName()); + + @Test + public void givenNoExplicitContructor_whenUsed_thenFails() { + BankAccount account = new BankAccount(); + assertThatThrownBy(() -> { account.toString(); }).isInstanceOf(Exception.class); + } + + @Test + public void givenNoArgumentConstructor_whenUsed_thenSucceeds() { + BankAccountEmptyConstructor account = new BankAccountEmptyConstructor(); + assertThatCode(() -> { + account.toString(); + }).doesNotThrowAnyException(); + } + + @Test + public void givenParameterisedConstructor_whenUsed_thenSucceeds() { + LocalDateTime opened = LocalDateTime.of(2018, Month.JUNE, 29, 06, 30, 00); + BankAccountParameterizedConstructor account = + new BankAccountParameterizedConstructor("Tom", opened, 1000.0f); + + assertThatCode(() -> { + account.toString(); + }).doesNotThrowAnyException(); + } + + @Test + public void givenCopyContructor_whenUser_thenMaintainsLogic() { + LocalDateTime opened = LocalDateTime.of(2018, Month.JUNE, 29, 06, 30, 00); + BankAccountCopyConstructor account = new BankAccountCopyConstructor("Tim", opened, 1000.0f); + BankAccountCopyConstructor newAccount = new BankAccountCopyConstructor(account); + + assertThat(account.getName()).isEqualTo(newAccount.getName()); + assertThat(account.getOpened()).isNotEqualTo(newAccount.getOpened()); + + assertThat(newAccount.getBalance()).isEqualTo(0.0f); + } +}