Notizen aus Lernsessions

.gitignore

@@ -70,3 +70,10 @@ crashlytics.properties
 crashlytics-build.properties
 fabric.properties
 
+/.idea/$CACHE_FILE$
+/.idea/$PRODUCT_WORKSPACE_FILE$
+/.idea/encodings.xml
+/.idea/misc.xml
+/.idea/modules.xml
+/.idea/oca8-lernen.iml
+/.idea/vcs.xml

src/org/eidecker/oca8lernen/general/Deklaration.java

@@ -0,0 +1,16 @@
+package org.eidecker.oca8lernen.general;
+
+import org.junit.jupiter.api.Test;
+
+public class Deklaration {
+
+	@Test
+	public void zuweisung() {
+		int a , b, c = 1;
+		// int d = e = 1; // Nicht erlaubt
+
+		System.out.println(c);
+
+	}
+
+}

src/org/eidecker/oca8lernen/general/FinallyTest.java

@@ -0,0 +1,52 @@
+package org.eidecker.oca8lernen.general;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class FinallyTest {
+
+	@Test
+	public void testFinally() {
+		int a = divZero(5);
+		assertEquals(5, a);
+	}
+
+
+	private int divZero(int a) {
+		try {
+			return a/0;
+		} catch (ArithmeticException e) {
+			return sideEffect();
+		} catch (Exception e) {
+			System.out.println("Exception vom Typ Exception gefangen");
+		} finally {
+			return 5;
+		}
+	}
+
+	@Test
+	public void exceptionBloecke() {
+
+		assertThrows(Exception.class, () -> {
+			try {
+				int a = 1/0;
+			} catch (ArithmeticException e) {
+				System.out.println("ArithmeticException gefangen");
+				throw new Exception();
+			} catch (Exception e) {
+				System.out.println("Exception vom Typ Exception gefangen");
+			} finally {
+				System.out.println("Finally");
+			}
+		});
+
+	}
+
+	private int sideEffect() {
+		System.out.println("Nur ein Seiteneffekt");
+		return 0;
+	}
+
+}

src/org/eidecker/oca8lernen/general/InterfaceWithFields.java

@@ -0,0 +1,41 @@
+package org.eidecker.oca8lernen.general;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class InterfaceWithFields implements T1, T2 {
+
+	public int getT1Value() {
+		return VALUE_T1;
+	}
+
+	public int getValue() {
+		return T2.VALUE;
+	}
+}
+
+interface T1 {
+	int VALUE = 99;
+	int VALUE_T1 = 1;
+}
+
+interface T2 {
+	int VALUE = 98;
+	int VALUE_T2 = 2;
+
+	default int getValue() {
+		return VALUE;
+	}
+}
+
+class Tester {
+
+	public void interfaceTest() {
+		InterfaceWithFields interfaceWithFields = new InterfaceWithFields();
+		assertEquals(99, ((T1)interfaceWithFields).VALUE);
+		assertEquals(98, ((T2)interfaceWithFields).VALUE);
+
+		assertEquals(1, interfaceWithFields.VALUE_T1);
+		assertEquals(2, interfaceWithFields.VALUE_T2);
+	}
+
+}

src/org/eidecker/oca8lernen/general/PrimitiveUndWrapperTest.java

@@ -0,0 +1,38 @@
+package org.eidecker.oca8lernen.general;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+
+public class PrimitiveUndWrapperTest {
+
+	@Test
+	public void wrapperEquals() {
+
+		Integer aIntegerType = 1;
+		Long aLongType = 1L;
+
+		Long anotherLongType = 0b1L;
+
+		int aInt = 1;
+		long aLong = 1L;
+
+		assertFalse(aIntegerType.equals(aLongType));
+		assertTrue(aInt == aLong);
+
+
+		assertTrue(aIntegerType == aLong);
+		assertTrue(aIntegerType == aInt);
+		assertTrue(aLongType == aInt);
+		assertTrue(aLongType == aLong);
+
+		assertFalse(aIntegerType.equals(aLong));
+		assertTrue(aIntegerType.equals(aInt));
+		assertTrue(aLongType.equals(aLong));
+		assertFalse(aLongType.equals(aInt));
+
+	}
+
+}

src/org/eidecker/oca8lernen/general/StaticInitError.java

@@ -0,0 +1,53 @@
+package org.eidecker.oca8lernen.general;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class StaticInitError {
+
+	public static int i = 0;
+	public static int j;
+
+	static {
+		j = 2 / i++;
+	}
+
+}
+
+class ConstructorInitError {
+
+	public ConstructorInitError() {
+		int a = 1/0;
+	}
+
+}
+
+
+class TesterStatic {
+
+	@Test
+	public void testInit() {
+		assertThrows(ExceptionInInitializerError.class, () -> {
+			StaticInitError staticInitError = new StaticInitError();
+		});
+
+		// Unterschiedlicher Error beim zweiten Mal. Die Klasse scheint nicht mehr verwendet zu werden.
+		assertThrows(NoClassDefFoundError.class, () -> {
+			StaticInitError staticInitError = new StaticInitError();
+		});
+	}
+
+	@Test
+	public void testConstructorInit() {
+		assertThrows(ArithmeticException.class, () -> {
+			ConstructorInitError constructorInitError = new ConstructorInitError();
+		});
+
+		assertThrows(ArithmeticException.class, () -> {
+			ConstructorInitError constructorInitError = new ConstructorInitError();
+		});
+	}
+
+}