Extract integers from string

Chapter10/ExtractIntegers/src/main/java/coding/challenge/Strings.java

@@ -17,7 +17,8 @@ public static List<Integer> extract(String str) {
         }
 
         List<Integer> result = new ArrayList<>();
-        StringBuilder temp = new StringBuilder(String.valueOf(Integer.MAX_VALUE).length());
+        StringBuilder temp = new StringBuilder(
+                String.valueOf(Integer.MAX_VALUE).length());
 
         for (int i = 0; i < str.length(); i++) {
 

Chapter10/ExtractSurrogatePairs/pom.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>coding.challenge</groupId>
+    <artifactId>ExtractIntegers</artifactId>
+    <version>1.0</version>
+    <packaging>jar</packaging>
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <maven.compiler.source>13</maven.compiler.source>
+        <maven.compiler.target>13</maven.compiler.target>
+    </properties>
+    <name>ExtractIntegers</name>
+</project>

Chapter10/ExtractSurrogatePairs/src/main/java/coding/challenge/Main.java

@@ -0,0 +1,13 @@
+package coding.challenge;
+
+public class Main {
+
+    public static void main(String[] args) {
+
+        String str = "cv dd 4 k 2321 2 11 k4k2 66 4d";        
+
+        System.out.println("String: " + str);                
+        System.out.println("Integers : " + Strings.extract(str));                
+    }
+
+}

Chapter10/ExtractSurrogatePairs/src/main/java/coding/challenge/Strings.java

@@ -0,0 +1,38 @@
+package coding.challenge;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public final class Strings {
+
+    private Strings() {
+        throw new AssertionError("Cannot be instantiated");
+    }
+
+    public static List<Integer> extract(String str) {
+
+        if (str == null || str.isBlank()) {
+            return Collections.emptyList();
+        }
+
+        List<Integer> result = new ArrayList<>();
+        StringBuilder temp = new StringBuilder(String.valueOf(Integer.MAX_VALUE).length());
+
+        for (int i = 0; i < str.length(); i++) {
+
+            char ch = str.charAt(i);
+
+            if (Character.isDigit(ch)) { // or, if (((int) ch) >= 48 && ((int) ch) <= 57)
+                temp.append(ch);
+            } else {
+                if (temp.length() > 0) {
+                    result.add(Integer.parseInt(temp.toString()));
+                    temp.delete(0, temp.length());
+                }
+            }
+        }
+
+        return result;
+    }
+}