From c46bc8612a622881691c36c1e6a6f8bcff8953fd Mon Sep 17 00:00:00 2001
From: Martin Goik <goik@hdm-stuttgart.de>
Date: Sun, 27 Sep 2020 12:28:52 +0200
Subject: [PATCH] Java 15 version of Ascii Xmas tree

---
 .../Ref/Statements/MoreFunXmasTree/pom.xml    |   4 +-
 .../java/de/hdm_stuttgart/mi/sd1/Xmas.java    |   3 +-
 .../hdm_stuttgart/mi/sd1/XmasUsingFormat.java |  21 ++-
 Doc/Sd1/statements.xml                        | 128 ++++++++----------
 4 files changed, 70 insertions(+), 86 deletions(-)

diff --git a/Doc/Sd1/Ref/Statements/MoreFunXmasTree/pom.xml b/Doc/Sd1/Ref/Statements/MoreFunXmasTree/pom.xml
index af1a514e..6ec7b1c9 100644
--- a/Doc/Sd1/Ref/Statements/MoreFunXmasTree/pom.xml
+++ b/Doc/Sd1/Ref/Statements/MoreFunXmasTree/pom.xml
@@ -25,8 +25,8 @@
         <artifactId>maven-compiler-plugin</artifactId>
         <version>3.8.1</version>
         <configuration>
-          <source>11</source>
-          <target>11</target>
+          <source>15</source>
+          <target>15</target>
         </configuration>
       </plugin>
 
diff --git a/Doc/Sd1/Ref/Statements/MoreFunXmasTree/src/main/java/de/hdm_stuttgart/mi/sd1/Xmas.java b/Doc/Sd1/Ref/Statements/MoreFunXmasTree/src/main/java/de/hdm_stuttgart/mi/sd1/Xmas.java
index b8da2388..b55f3185 100644
--- a/Doc/Sd1/Ref/Statements/MoreFunXmasTree/src/main/java/de/hdm_stuttgart/mi/sd1/Xmas.java
+++ b/Doc/Sd1/Ref/Statements/MoreFunXmasTree/src/main/java/de/hdm_stuttgart/mi/sd1/Xmas.java
@@ -1,7 +1,8 @@
 package de.hdm_stuttgart.mi.sd1;
 
 /**
- * Beginner's way of implementing the »More fun with X-mas trees« exercise.
+ * Beginner's way of implementing the »More fun with X-mas trees« exercise. This solution just uses
+ * »bare-bone« print statements.
  */
 public class Xmas {
 
diff --git a/Doc/Sd1/Ref/Statements/MoreFunXmasTree/src/main/java/de/hdm_stuttgart/mi/sd1/XmasUsingFormat.java b/Doc/Sd1/Ref/Statements/MoreFunXmasTree/src/main/java/de/hdm_stuttgart/mi/sd1/XmasUsingFormat.java
index de2222ce..62dddd3d 100644
--- a/Doc/Sd1/Ref/Statements/MoreFunXmasTree/src/main/java/de/hdm_stuttgart/mi/sd1/XmasUsingFormat.java
+++ b/Doc/Sd1/Ref/Statements/MoreFunXmasTree/src/main/java/de/hdm_stuttgart/mi/sd1/XmasUsingFormat.java
@@ -2,7 +2,7 @@ package de.hdm_stuttgart.mi.sd1;
 
 
 /**
- * Simplified implementation replacing loops by {@link java.io.PrintStream#format(String, Object...)} and
+ * Simplified implementation replacing loops by {@link String#indent(int)} and
  * {@link String#repeat(int)}.
  */
 public class XmasUsingFormat {
@@ -28,25 +28,24 @@ public class XmasUsingFormat {
 
         final int numberOfRowGroups = 5;                   // You may easily change this parameter.
 
-        // Printing the tree's top
-        System.out.format("%"+ (numberOfRowGroups + 5) + "s\n",     "\\ /");
-        System.out.format("%"+ (numberOfRowGroups + 7) + "s\n",    "-->*<--");
-        System.out.format("%"+ (numberOfRowGroups + 5) + "s\n",      "/_\\");
+        // Printing the tree's top. We have to escape the backslash using \\.
+        System.out.print("""                
+                      \\ /
+                    -->*<--
+                      /_\\""".indent(numberOfRowGroups));
 
         // Printing the tree's body
 
         // Loop printing the tree's body row group wise.
         for (int rowGroup = 0; rowGroup < numberOfRowGroups; rowGroup++) {
-
+            final int indentation = numberOfRowGroups - rowGroup + 1;
             // First body line of current group
-            System.out.format("%"+ (numberOfRowGroups + rowGroup + 6) + "s\n", "/" + "_\\".repeat(rowGroup + 2));
+            System.out.print(('/' + "_\\".repeat(rowGroup + 2)).indent(indentation));
 
             // Second body line of current group
-            System.out.format
-                    ("%"+ (numberOfRowGroups + rowGroup + 6) + "s\\\n",
-                     "/_".repeat(rowGroup + 3));
+            System.out.print(("/_".repeat(rowGroup + 2) + '\\').indent(indentation));
         }
         // Printing the tree's trunk
-        System.out.format("%"+ (numberOfRowGroups + 6) + "s\n", "[___]");
+        System.out.print("[___]".indent(numberOfRowGroups + 1));
     }
 }
diff --git a/Doc/Sd1/statements.xml b/Doc/Sd1/statements.xml
index cf33dcf3..58b62380 100644
--- a/Doc/Sd1/statements.xml
+++ b/Doc/Sd1/statements.xml
@@ -3045,7 +3045,8 @@ for (int row = 0; row &lt; numberOfRows; row++) { <co
             <answer>
               <para>We start coding the proposed helper exercise. Each line
               has to be indented using space <code>' '</code> characters being
-              represented by <quote>␣</quote> in the right diagram:</para>
+              represented by <quote><emphasis role="red">␣</emphasis></quote>
+              in the right diagram:</para>
 
               <informaltable border="1">
                 <col width="47%"/>
@@ -3071,12 +3072,12 @@ for (int row = 0; row &lt; numberOfRows; row++) {
 
                   <td align="center">⟹</td>
 
-                  <td valign="top"><screen>␣␣␣␣␣␣*
-␣␣␣␣␣**
-␣␣␣␣***
-␣␣␣****
-␣␣*****
-␣******
+                  <td valign="top"><screen><emphasis role="red">␣␣␣␣␣␣</emphasis>*
+<emphasis role="red">␣␣␣␣␣</emphasis>**
+<emphasis role="red">␣␣␣␣</emphasis>***
+<emphasis role="red">␣␣␣</emphasis>****
+<emphasis role="red">␣␣</emphasis>*****
+<emphasis role="red">␣</emphasis>******
 *******</screen></td>
                 </tr>
               </informaltable>
@@ -3102,23 +3103,23 @@ Row index 5   ***********
               <para>We require the precise indentation values when
               <abbrev>e.g.</abbrev> starting the tree's body. The following
               sketch shows two trees of different sizes representing invisible
-              spaces by <quote>␣</quote>. In the »bigger« tree's first line we
-              need <abbrev>e.g.</abbrev> 5 spaces before actually printing the
-              tree's very top <emphasis
-              role="red"><code>X</code></emphasis></para>
+              spaces by <quote><emphasis role="red">␣</emphasis></quote>. In
+              the »bigger« tree's first line we need <abbrev>e.g.</abbrev> 5
+              spaces before actually printing the tree's very top
+              <code>'X'</code> character.</para>
 
-              <screen language="none">  A tree with          A tree with
+              <screen language="none">  A tree with         A tree with
   6 body rows         2 row groups
 
-␣␣␣␣␣<emphasis role="red">X</emphasis>                ␣␣␣<emphasis role="red">X</emphasis>
-␣␣␣␣␣*                ␣␣␣*  
-␣␣␣␣***               ␣␣***  
-␣␣␣*****              ␣*****   
-␣␣*******             *******
-␣*********            ␣␣<emphasis role="red">###</emphasis>
+<emphasis role="red">␣␣␣␣␣</emphasis>X                <emphasis role="red">␣␣␣</emphasis>X
+<emphasis role="red">␣␣␣␣␣</emphasis>*                <emphasis role="red">␣␣␣</emphasis>*
+<emphasis role="red">␣␣␣␣</emphasis>***               <emphasis role="red">␣␣</emphasis>***
+<emphasis role="red">␣␣␣</emphasis>*****              <emphasis role="red">␣</emphasis>*****
+<emphasis role="red">␣␣</emphasis>*******             *******
+<emphasis role="red">␣</emphasis>*********            <emphasis role="red">␣␣</emphasis>###
 ***********
-␣␣␣␣<emphasis role="red">###</emphasis>
-␣␣␣␣<emphasis role="red">###</emphasis></screen>
+<emphasis role="red">␣␣␣␣</emphasis>###
+<emphasis role="red">␣␣␣␣</emphasis>###</screen>
 
               <para>The precise amounts of these indentations depend on the
               tree's size. Printing larger trees requires larger indentation
@@ -3129,7 +3130,7 @@ Row index 5   ***********
 
               <para>We start printing the tree's top. This requires <code
               language="java">numberOfRows</code> space characters followed by
-              the top's <emphasis role="red">X</emphasis> character:</para>
+              the top's <code role="red">'X'</code> character:</para>
 
               <informaltable border="1">
                 <col width="80%"/>
@@ -3147,11 +3148,11 @@ Row index 5   ***********
                         role="red">X</emphasis>" top. We need
   System.out.print(' ');                          // numberOfRowGroups preceding spaces (␣)
 }                                                 // before eventually printing the
-System.out.println("<emphasis role="red">X</emphasis>");                          // "<emphasis
+System.out.println('<emphasis role="red">X</emphasis>');                          // "<emphasis
                         role="red">X</emphasis>" String followed by a newline (print<emphasis
                         role="red">ln</emphasis>).</programlisting></td>
 
-                  <td valign="top"><screen>␣␣␣␣␣<emphasis role="red">X</emphasis>  </screen><para>(<quote>␣</quote>
+                  <td valign="top"><screen><emphasis role="red">␣␣␣␣␣</emphasis>X</screen><para>(<quote>␣</quote>
                   denoting space)</para></td>
                 </tr>
               </informaltable>
@@ -3182,7 +3183,7 @@ System.out.println("<emphasis role="red">X</emphasis>");
      System.out.print(' ');                           // (numberOfRows - row)
    }                                                  // space (␣) characters ...
 
-  for (int x = 0; x &lt; 2 * row + 1; x ++) {            // .. then printing (2*row+1)
+  for (int x = 0; x &lt; 2 * row + 1; x ++) {            // .. then printing (2 * row + 1)
                                                       // asterisk('<emphasis
                         role="red">*</emphasis>') characters ...
     System.out.print('<emphasis role="red">*</emphasis>');                            // (May try  '<emphasis
@@ -3191,28 +3192,13 @@ System.out.println("<emphasis role="red">X</emphasis>");
   System.out.print("\n");                             // ... and finally terminating the
 }                                                     // current body row.</programlisting></td>
 
-                  <td valign="top"><screen>␣␣␣␣␣X
-␣␣␣␣␣<emphasis role="red">*</emphasis>
-␣␣␣␣<emphasis role="red">*</emphasis><emphasis role="red">*</emphasis><emphasis
-                        role="red">*</emphasis>
-␣␣␣<emphasis role="red">*</emphasis><emphasis role="red">*</emphasis><emphasis
-                        role="red">*</emphasis><emphasis role="red">*</emphasis><emphasis
-                        role="red">*</emphasis>
-␣␣<emphasis role="red">*</emphasis><emphasis role="red">*</emphasis><emphasis
-                        role="red">*</emphasis><emphasis role="red">*</emphasis><emphasis
-                        role="red">*</emphasis><emphasis role="red">*</emphasis><emphasis
-                        role="red">*</emphasis>
-␣<emphasis role="red">*</emphasis><emphasis role="red">*</emphasis><emphasis
-                        role="red">*</emphasis><emphasis role="red">*</emphasis><emphasis
-                        role="red">*</emphasis><emphasis role="red">*</emphasis><emphasis
-                        role="red">*</emphasis><emphasis role="red">*</emphasis><emphasis
-                        role="red">*</emphasis>
-<emphasis role="red">*</emphasis><emphasis role="red">*</emphasis><emphasis
-                        role="red">*</emphasis><emphasis role="red">*</emphasis><emphasis
-                        role="red">*</emphasis><emphasis role="red">*</emphasis><emphasis
-                        role="red">*</emphasis><emphasis role="red">*</emphasis><emphasis
-                        role="red">*</emphasis><emphasis role="red">*</emphasis><emphasis
-                        role="red">*</emphasis></screen></td>
+                  <td valign="top"><screen><emphasis role="red">␣␣␣␣␣</emphasis>X
+<emphasis role="red">␣␣␣␣␣</emphasis>*
+<emphasis role="red">␣␣␣␣</emphasis>***
+<emphasis role="red">␣␣␣</emphasis>*****
+<emphasis role="red">␣␣</emphasis>*******
+<emphasis role="red">␣</emphasis>*********
+***********</screen></td>
                 </tr>
               </informaltable>
 
@@ -3426,11 +3412,11 @@ System.out.format("%"+ (numberOfRows + 1) + "s\n", "###");</programlisting>
             </question>
 
             <answer>
-              <para>A complete solution is available at the <link
-              xlink:href="https://gitlab.mi.hdm-stuttgart.de/goik/GoikLectures/tree/master/Doc/Sd1/Ref/Statements/MoreFunXmasTree/src/main/java/de/hdm_stuttgart/mi/sd1/Xmas.java">MI
-              Gitlab</link> repository. We start again from a version being
-              fully covered by our current knowledge. This time we try
-              printing the following lines:</para>
+              <para>A complete solution is provided by <link
+              xlink:href="https://gitlab.mi.hdm-stuttgart.de/goik/GoikLectures/tree/master/Doc/Sd1/Ref/Statements/MoreFunXmasTree/src/main/java/de/hdm_stuttgart/mi/sd1/Xmas.java">Xmas.java</link>.
+              You may want to import the whole project. We start again from a
+              version being fully covered by our current knowledge. This time
+              we try printing the following lines:</para>
 
               <programlisting language="none">Looping through         <emphasis
                   role="red">\ /</emphasis>           <emphasis role="red">Part 1: The tree's top.</emphasis>
@@ -3724,40 +3710,38 @@ System.out.println("<emphasis role="red">[___]</emphasis>");
                 </tr>
               </informaltable>
 
-              <para>Like in the previous exercise <xref
-              linkend="sd1QandaXmasTree"/> we now replace all inner loops
-              by<classname>
-              System</classname><code>.</code><property>out</property><code>.</code><methodname
-              xlink:href="https://docs.oracle.com/en/java/javase/14/docs/api/java.base/java/io/PrintStream.html#format(java.lang.String,java.lang.Object...)">format()</methodname>
+              <para>Similar to the previous exercise <xref
+              linkend="sd1QandaXmasTree"/> this time we replace all inner
+              loops by<classname> using </classname><classname
+              xlink:href="https://docs.oracle.com/en/java/javase/14/docs/api/java.base/java/lang/String.html">String</classname>.<methodname
+              xlink:href="https://docs.oracle.com/en/java/javase/14/docs/api/java.base/java/lang/String.html#indent(int)">indent()</methodname>
               and <classname
               xlink:href="https://docs.oracle.com/en/java/javase/14/docs/api/java.base/java/lang/String.html">String</classname>.<methodname
               xlink:href="https://docs.oracle.com/en/java/javase/14/docs/api/java.base/java/lang/String.html#repeat(int)">repeat()</methodname>.
-              This variants full source code is on offer at <link
+              This variant's full source code is on offer at <link
               xlink:href="https://gitlab.mi.hdm-stuttgart.de/goik/GoikLectures/tree/master/Doc/Sd1/Ref/Statements/MoreFunXmasTree/src/main/java/de/hdm_stuttgart/mi/sd1/XmasUsingFormat.java">XmasUsingFormat.java</link>.</para>
 
-              <programlisting language="java">final int numberOfRowGroups = 5;                   // You may easily change this parameter.
+              <programlisting language="java">final int numberOfRowGroups = 5;      // You may easily change this parameter.
 
-// Printing the tree's top
-System.out.format("%"+ (numberOfRowGroups + 5) + "s\n",     "\\ /");
-System.out.format("%"+ (numberOfRowGroups + 7) + "s\n",    "--&gt;*&lt;--");
-System.out.format("%"+ (numberOfRowGroups + 5) + "s\n",      "/_\\");
+// Printing the tree's top. We have to escape the backslash using \\.
+System.out.print("""                
+              \\ /
+            --&gt;*&lt;--
+              /_\\""".indent(numberOfRowGroups));
 
 // Printing the tree's body
 
 // Loop printing the tree's body row group wise.
 for (int rowGroup = 0; rowGroup &lt; numberOfRowGroups; rowGroup++) {
+    final int indentation = numberOfRowGroups - rowGroup + 1;
+    // First body line of current group
+    System.out.print(('/' + "_\\".repeat(rowGroup + 2)).indent(indentation));
 
-  // First body line of current group
-  System.out.format("%"+ (numberOfRowGroups + rowGroup + 6) + "s\n", "/" + "_\\".repeat(rowGroup + 2));
-
-  // Second body line of current group
-  System.out.format
-    ("%"+ (numberOfRowGroups + rowGroup + 6) + "s\\\n",
-    "/_".repeat(rowGroup + 3));
-  }
+    // Second body line of current group
+    System.out.print(("/_".repeat(rowGroup + 2) + '\\').indent(indentation));
+}
 // Printing the tree's trunk
-System.out.format("%"+ (numberOfRowGroups + 6) + "s\n", "[___]");
-</programlisting>
+System.out.print("[___]".indent(numberOfRowGroups + 1));</programlisting>
 
               <para>Both implementation variants allow for setting e.g. <code
               language="java">final int numberOfRowGroups = 8</code> creating
-- 
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