rename most of the chapters (again)

Author: forax

README.md

@@ -4,32 +4,33 @@ A guide to modern Java (Java 17)
 ## Content
 
 0. [genesis.md](guide/chapter00-genesis.md)
-1. [basictypes.md](guide/chapter01-basictypes.md)
+1. [basic_types.md](guide/chapter01-basic_types.md)
 2. [methods.md](guide/chapter02-methods.md)
-3. [jshellvsjava.md](guide/chapter03-jshellvsjava.md)
+3. [jshell_vs_java.md](guide/chapter03-jshell_vs_java.md)
 4. [numbers.md](guide/chapter04-numbers.md)
-5. [controlflow.md](guide/chapter05-controlflow.md)
+5. [control_flow.md](guide/chapter05-control_flow.md)
 6. [interface.md](guide/chapter07-interface.md)
 7. [lambda.md](guide/chapter08-lambda.md)
-8. [listandmap.md](guide/chapter09-listandmap.md)
-9. [stringformatting.md](guide/chapter10-stringformatting.md)
+8. [list_and_map.md](guide/chapter09-list_and_map.md)
+9. [string_formatting.md](guide/chapter10-string_formatting.md)
 10. [encapsulation.md](guide/chapter11-encapsulation.md)
 11. [equals_hashCode_toString.md](guide/chapter12-equals_hashCode_toString.md)
 12. [contract.md](guide/chapter13-contract.md)
 13. [modifable_vs_mutalble.md](guide/chapter13-modifable_vs_mutalble.md)
-14. [nullandoptional.md](guide/chapter14-nullandoptional.md)
+14. [null_and_optional.md](guide/chapter14-null_and_optional.md)
 15. [inheritance.md](guide/chapter15-inheritance.md)
 16. [exception.md](guide/chapter16-exception.md)
 17. [enum.md](guide/chapter17-enum.md)
-18. [internalclass.md](guide/chapter18-internalclass.md)
+18. [internal_classes.md](guide/chapter18-internal_classes.md)
 19. [implementing_interface.md](guide/chapter19-implementing_interface.md)
 20. [generics.md](guide/chapter20-generics.md)
 21. [wrapper.md](guide/chapter21-wrapper.md)
 22. [variance.md](guide/chapter22-variance.md)
-23. [stream.md](guide/chapter25-stream.md)
-24. [collector.md](guide/chapter26-collector.md)
-25. [datastructure.md](guide/chapter30-datastructure.md)
-26. [sort.md](guide/chapter31-sort.md)
+23. [limitation_of_generics.md](guide/chapter23-limitation_of_generics.md)
+24. [stream.md](guide/chapter25-stream.md)
+25. [collector.md](guide/chapter26-collector.md)
+26. [data_structure.md](guide/chapter30-data_structure.md)
+27. [sort.md](guide/chapter31-sort.md)
 
 
 ## Using Java Shell (jshell)

chapter01-basictypes.jsh renamed to chapter01-basic_types.jsh

@@ -2,3 +2,37 @@
 // then cut and paste the following lines to see how it works
 // To exit jshell type /exit
 
+// # Contract
+
+public enum UnitKind {
+  MARINE(10), FLAME_THROWER(8)
+  ;
+  private final int maxPower;
+  
+  private UnitKind(int maxPower) {
+    this.maxPower = maxPower;
+  }
+}
+
+public class MilitaryUnit {
+  private final UnitKind kind;
+  private final int power;
+  private IntUnaryOperator bonus;
+  
+  public MilitaryUnit(UnitKind kind, int power) {
+    this.kind = Objects.requireNonNull(kind);
+    if (power < 0 || power >= kind.maxPower) {
+      throw new IllegalArgumentException("invalid power " + power);
+    }
+    this.power = power;
+    this.bonus = x -> x;
+  }
+  
+  public void bonus(IntUnaryOperator bonus) {
+    this.bonus = Objects.requireNonNull(bonus);
+  }
+  
+  public int fightingPower() {
+    return Math.max(0, Math.min(unit.maxPower, bonus.applyAsInt(power)));
+  }
+}

chapter03-jshellvsjava.jsh renamed to chapter03-jshell_vs_java.jsh

@@ -0,0 +1,17 @@
+// To starts, run jshell --enable-preview which is a program able to interpret Java syntax
+// then cut and paste the following lines to see how it works
+// To exit jshell type /exit
+
+
+// # Limitations of generics
+
+
+// ## No reification
+
+
+
+// ## Array of parameterized type
+
+
+// ### varargs
+

chapter05-controlflow.jsh renamed to chapter05-control_flow.jsh

@@ -1 +1,47 @@
 
+# Contract
+
+```java
+public enum UnitKind {
+  MARINE(10), FLAME_THROWER(8)
+  ;
+  private final int maxPower;
+```
+  
+```java
+  private UnitKind(int maxPower) {
+    this.maxPower = maxPower;
+  }
+}
+```
+
+```java
+public class MilitaryUnit {
+  private final UnitKind kind;
+  private final int power;
+  private IntUnaryOperator bonus;
+```
+  
+```java
+  public MilitaryUnit(UnitKind kind, int power) {
+    this.kind = Objects.requireNonNull(kind);
+    if (power < 0 || power >= kind.maxPower) {
+      throw new IllegalArgumentException("invalid power " + power);
+    }
+    this.power = power;
+    this.bonus = x -> x;
+  }
+```
+  
+```java
+  public void bonus(IntUnaryOperator bonus) {
+    this.bonus = Objects.requireNonNull(bonus);
+  }
+```
+  
+```java
+  public int fightingPower() {
+    return Math.max(0, Math.min(unit.maxPower, bonus.applyAsInt(power)));
+  }
+}
+```

chapter09-listandmap.jsh renamed to chapter09-list_and_map.jsh

@@ -0,0 +1,14 @@
+
+
+# Limitations of generics
+
+
+## No reification
+
+
+
+## Array of parameterized type
+
+
+### varargs
+