From eed72f2034278290a866320d73c4b8581d2cd117 Mon Sep 17 00:00:00 2001 From: Sebastian Eidecker Date: Sun, 17 Nov 2019 21:48:08 +0100 Subject: [PATCH] Lernen am Sonntag --- .../oca8lernen/lastminute/ArrayThings.java | 35 +++++++++++++ .../oca8lernen/lastminute/Aufgabe10.java | 29 +++++++++++ .../oca8lernen/lastminute/Kleinigkeiten.java | 51 +++++++++++++++++++ 3 files changed, 115 insertions(+) create mode 100644 src/org/eidecker/oca8lernen/lastminute/ArrayThings.java create mode 100644 src/org/eidecker/oca8lernen/lastminute/Aufgabe10.java diff --git a/src/org/eidecker/oca8lernen/lastminute/ArrayThings.java b/src/org/eidecker/oca8lernen/lastminute/ArrayThings.java new file mode 100644 index 0000000..7d83a03 --- /dev/null +++ b/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); + } + +} diff --git a/src/org/eidecker/oca8lernen/lastminute/Aufgabe10.java b/src/org/eidecker/oca8lernen/lastminute/Aufgabe10.java new file mode 100644 index 0000000..d00662d --- /dev/null +++ b/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; + } +}*/ diff --git a/src/org/eidecker/oca8lernen/lastminute/Kleinigkeiten.java b/src/org/eidecker/oca8lernen/lastminute/Kleinigkeiten.java index c0db8a5..3b26733 100644 --- a/src/org/eidecker/oca8lernen/lastminute/Kleinigkeiten.java +++ b/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; + } + } + } + + } }