Gemeinsames Lernen

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

@@ -0,0 +1,112 @@
+package org.eidecker.oca8lernen.general;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.io.IOException;
+import java.math.BigDecimal;
+import java.nio.file.AccessDeniedException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Optional;
+import org.junit.jupiter.api.Test;
+
+/**
+ * @author seidecke.
+ */
+public class Lernkleinigkeiten {
+
+	@Test
+	public void optionalMapping() {
+		Optional<BigDecimal> maybeBigDecimal = Optional.ofNullable(BigDecimal.ONE);
+		Optional<Kosten> maybeKosten;// = Optional.of(new Kosten());
+
+		maybeKosten = maybeBigDecimal.map(Kosten::new);
+		maybeBigDecimal = maybeKosten.map(Kosten::getValue);
+		maybeBigDecimal = Optional.of(maybeKosten.get().getValue());
+	}
+
+	@Test
+	public void testPolymorphieUndFelder() throws Exception {
+		Ober2 ober = new Unter2();
+		System.out.println(ober.s);
+		System.out.println(ober.s2);
+
+		Unter2 unter = new Unter2();
+		System.out.println(unter.s);
+		System.out.println(unter.s2);
+	}
+
+	@Test
+	public void returnSyntaxTest() {
+		assertEquals(1, returnSyntax(1));
+		throwNull();
+	}
+
+	private int returnSyntax(int i) {
+		;;;;;;;;;;;;
+		if (i == 1) {
+			return(1);
+		} else {
+			return (i + 1);
+		}
+	};
+
+	private int throwNull() {
+		throw null;
+	}
+
+}
+
+
+
+class Kosten {
+	public Kosten(BigDecimal value) {
+	}
+
+	BigDecimal getValue() {
+		if (false) {
+		}
+		return BigDecimal.ONE;
+	}
+
+	BigDecimal getValueUnsafe() throws IOException {
+		if (false) {
+		}
+		return BigDecimal.ONE;
+	}
+}
+
+
+class Ober2 {
+
+	public String s = "Ober2";
+	public String s2 = "Noch ein Feld aus Ober2";
+
+	public Ober2() throws IOException {
+	}
+
+	public List getS() throws IOException {
+		return Collections.singletonList(s);
+	}
+};
+
+class Unter2 extends Ober2 {
+
+	public String s = "Unter2";
+
+	public Unter2() throws Exception{
+	}
+
+	@Override
+	public ArrayList getS() throws AccessDeniedException {
+		int i = 1;
+		do {
+
+		} while (i == 1);
+
+		return new ArrayList();
+	}
+}
+
+

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

@@ -15,11 +15,11 @@ public class PrimitiveUndWrapperTest {
 		char c = (char) 1L;
 
 		short sh = Short.MAX_VALUE;
-		char s = sh;
+//		char s = sh;
 
-		"Hallo".concat()
+		"Hallo".concat(" Welt");
 
-		System.out.println(s);
+//		System.out.println(s);
 	}
 
 	@Test

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

@@ -10,9 +10,14 @@ public class SwitchSyntax {
 		Integer i = 1;
 
 		switch(getSwitchBEdingung()) {
-			case 1:
+			case 1: {
-				System.out.println("1");
+					int j;
+					System.out.println("1");
+				break;
+				}
+			case 3:
 			default:
+				int j;
 				System.out.println("default");
 		}
 	}