object orientation introduction

.gitignore

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+/.metadata/

bytebank/.classpath

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+<?xml version="1.0" encoding="UTF-8"?>
+<classpath>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-17">
+		<attributes>
+			<attribute name="module" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="src" path="src"/>
+	<classpathentry kind="output" path="bin"/>
+</classpath>

bytebank/.gitignore

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+/bin/

bytebank/.project

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+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>bytebank</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.eclipse.jdt.core.javabuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.eclipse.jdt.core.javanature</nature>
+	</natures>
+</projectDescription>

bytebank/.settings/org.eclipse.jdt.core.prefs

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+eclipse.preferences.version=1
+org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
+org.eclipse.jdt.core.compiler.codegen.targetPlatform=17
+org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
+org.eclipse.jdt.core.compiler.compliance=17
+org.eclipse.jdt.core.compiler.debug.lineNumber=generate
+org.eclipse.jdt.core.compiler.debug.localVariable=generate
+org.eclipse.jdt.core.compiler.debug.sourceFile=generate
+org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
+org.eclipse.jdt.core.compiler.problem.enablePreviewFeatures=disabled
+org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
+org.eclipse.jdt.core.compiler.problem.reportPreviewFeatures=warning
+org.eclipse.jdt.core.compiler.release=enabled
+org.eclipse.jdt.core.compiler.source=17

bytebank/src/bytebank/Account.java

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+package bytebank;
+
+public class Account {
+	double balance;
+	int agency = 42;
+	int number;
+	String owner;
+}

bytebank/src/bytebank/CreateAccount.java

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+package bytebank;
+
+public class CreateAccount {
+	public static void main(String[] args) {
+		Account firstAccount = new Account();
+		firstAccount.balance = 200;
+		firstAccount.balance += 100;
+
+		Account secondAccount = new Account();
+		secondAccount.balance = 50;
+
+		System.out.println("first account has: " + firstAccount.balance);
+		System.out.println("first account is in "
+				+ "agency " + firstAccount.agency);
+		System.out.println(firstAccount.number);
+		System.out.println(firstAccount.owner);
+
+		System.out.println("second account has: " + secondAccount.balance);
+		System.out.println("second account is in "
+				+ "agency " + secondAccount.agency);
+		System.out.println(secondAccount.number);
+		System.out.println(secondAccount.owner);
+
+		if (firstAccount == secondAccount) {
+			System.out.println("they are the same account");
+		} else {
+			System.out.println("they are different accounts");
+		}
+
+		System.out.println(firstAccount);
+		System.out.println(secondAccount);
+	}
+}

bytebank/src/bytebank/ReferencesTest.java

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+package bytebank;
+
+public class ReferencesTest {
+	public static void main(String[] args) {
+		Account firstAccount = new Account();
+		firstAccount.balance = 300;
+		System.out.println("balance of first account: " + firstAccount.balance);
+
+		Account secondAccount = firstAccount;
+		System.out.println("balance of first account: " + secondAccount.balance);
+
+		secondAccount.balance += 100;
+		System.out.println("balance of first account: " + firstAccount.balance);
+		System.out.println("balance of first account: " + secondAccount.balance);
+
+		if(firstAccount == secondAccount) {
+			System.out.println("they are the same account");
+		}
+
+		System.out.println(firstAccount);
+		System.out.println(secondAccount);
+	}
+}