Lernen am Sonntag

src/org/eidecker/oca8lernen/lastminute/ArrayThings.java

@@ -0,0 +1,35 @@
+package org.eidecker.oca8lernen.lastminute;
+
+import org.junit.jupiter.api.Test;
+
+public class ArrayThings {
+
+	@Test
+	public void funWithArrays() {
+		int [][] a = {{1,2}, {1}};
+		System.out.println("Hallo");
+
+		String [] strings;
+
+		long [][] b = {{1,2}, {1}};
+
+		int[] ints;
+		long [] longs;
+
+	/*	longs = (long[])ints;
+
+		a = (int[][])b;
+
+		if (a instanceof long[][])
+
+		if (strings instanceof String[])*/
+	}
+
+	@Test
+	public void someMoreFun() {
+		short[][][][] b2 = new short[2][3][2][2];
+		b2[1][1] = new short[4][4];
+		System.out.println(b2);
+	}
+
+}

src/org/eidecker/oca8lernen/lastminute/Aufgabe10.java

@@ -0,0 +1,29 @@
+package org.eidecker.oca8lernen.lastminute;
+
+public class Aufgabe10 {
+}
+
+class Ping extends Utils {
+	public static void main(String[] args) throws Exception {
+		Utils u = new Ping();
+		System.out.println(u.getInt(args[0]));
+	}
+
+	int getInt(String a) {
+		//return super.getInt(a);
+		return Integer.parseInt(a);
+	}
+}
+
+class Utils {
+	int getInt(String x) throws Exception {
+		return 7;
+	}
+}
+
+/*
+interface Integer {
+	static int parseInt(String s) throws Exception {
+		return 4;
+	}
+}*/

src/org/eidecker/oca8lernen/lastminute/Kleinigkeiten.java

@@ -4,6 +4,7 @@ import org.eidecker.oca8lernen.lastminute.hilfspackage.KlasseInEinemAnderenPacka
 import org.junit.jupiter.api.Test;
 
 import java.io.Serializable;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.concurrent.ThreadFactory;
@@ -44,6 +45,56 @@ public class Kleinigkeiten {
 
 	}
 
+	@Test
+	public void wrapperSindImmutable() {
+		Integer I1 = 42;
+		Integer I2 = I1;
+		System.out.println(I1 == I2);
+		I1 += 1;
+		System.out.println(I1 == I2);
+
+
+		System.out.println(I1);
+
+	}
+
+	@Test
+	public void laengen() {
+		int[] a = {};
+		int i = a.length;
+
+		"Hallo".length();
+		new StringBuilder("Hallo").length();
+
+		new ArrayList<>().size();
+	}
+
+	@Test
+	public void incrementInFor() {
+
+		int j = 0;
+		for (j = 0; j < 6; System.out.println("Anweisung in Schleife" + j++)) {
+			System.out.println(j);
+			if (j == 3) break;
+		}
+		System.out.println("Ende: " + j);
+
+	}
+
+	@Test
+	public void schleifenvariablenSichtbarkeit() {
+		int[] ints = {1,2,3,4,5,6};
+		for (int i = 0; i < 10; i++) {
+			for (int i2 : ints) {
+				System.out.println(i + ": " + i2);
+				for (;i2<2;) {
+					System.out.println("Ganz innen " + i2);
+					break;
+				}
+			}
+		}
+
+	}
 
 }