BAEL-5656 Constructing a Relative Path in Java from Two Absolute Paths or URLs (#12726)

core-java-modules/core-java-io-apis-2/README.md

@@ -0,0 +1,5 @@
+## Core Java IO APIs
+
+This module contains articles about core Java input/output(IO) APIs.
+
+### Relevant Articles:

core-java-modules/core-java-io-apis-2/pom.xml

@@ -0,0 +1,47 @@
+<?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>
+    <artifactId>core-java-io-apis-2</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <name>core-java-io-apis-2</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <!-- logging -->
+        <dependency>
+            <groupId>log4j</groupId>
+            <artifactId>log4j</artifactId>
+            <version>${log4j.version}</version>
+        </dependency>
+        <dependency> <!-- needed to bridge to slf4j for projects that use the log4j APIs directly -->
+            <groupId>org.slf4j</groupId>
+            <artifactId>log4j-over-slf4j</artifactId>
+            <version>${org.slf4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>${lombok.version}</version>
+            <scope>provided</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>core-java-io-apis-2</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+    </build>
+
+</project>

core-java-modules/core-java-io-apis-2/src/test/java/com/baeldung/absolutetorelative/AbsoluteToRelativeUnitTest.java

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+package com.baeldung.absolutetorelative;
+
+import org.assertj.core.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.net.URI;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+public class AbsoluteToRelativeUnitTest {
+
+    // given - until using Paths, no need to create physical files
+    private final Path pathOne = Paths.get("/baeldung/bar/one.txt");
+    private final Path pathTwo = Paths.get("/baeldung/bar/two.txt");
+    private final Path pathThree = Paths.get("/baeldung/foo/three.txt");
+
+    private final URI uriOne = pathOne.toUri();
+    private final URI uriTwo = pathTwo.toUri();
+    private final URI uriThree = pathThree.toUri();
+
+    @Test
+    public void givenAbsolutePaths_whenRelativizePathOneToPathTwo_thenRelativeIsReturned() {
+        Path result = pathOne.relativize(pathTwo);
+
+        Assertions.assertThat(result)
+                .isRelative()
+                .isEqualTo(Paths.get("../two.txt"));
+    }
+
+    @Test
+    public void givenAbsolutePaths_whenRelativizePathTwoToPathOne_thenRelativeIsReturned() {
+        Path result = pathTwo.relativize(pathOne);
+
+        Assertions.assertThat(result)
+                .isRelative()
+                .isEqualTo(Paths.get("../one.txt"));
+    }
+
+    @Test
+    public void givenAbsolutePaths_whenRelativizePathOneParentToPathTwo_thenRelativeIsReturned() {
+        Path result = pathOne.getParent().relativize(pathTwo);
+
+        Assertions.assertThat(result)
+                .isRelative()
+                .isEqualTo(Paths.get("two.txt"));
+    }
+
+    @Test
+    public void givenAbsolutePaths_whenRelativizePathOneToPathThree_thenRelativeIsReturned() {
+        Path result = pathOne.relativize(pathThree);
+
+        Assertions.assertThat(result)
+                .isRelative()
+                .isEqualTo(Paths.get("../../foo/three.txt"));
+    }
+
+    @Test
+    public void givenAbsolutePaths_whenRelativizePathThreeToPathOne_thenRelativeIsReturned() {
+        Path result = pathThree.relativize(pathOne);
+
+        Assertions.assertThat(result)
+                .isRelative()
+                .isEqualTo(Paths.get("../../bar/one.txt"));
+    }
+
+    @Test
+    public void givenAbsoluteURIs_whenRelativizeUriOneToUriTwo_thenAbsoluteIsReturned() {
+        URI result = uriOne.relativize(uriTwo);
+
+        Assertions.assertThat(result)
+                .asString()
+                .contains("/baeldung/bar/two.txt");
+    }
+
+    @Test
+    public void givenAbsoluteURIs_whenRelativizeUriOneParentToUriTwo_thenRelativeIsReturned() {
+        URI result = pathOne.getParent().toUri().relativize(uriTwo);
+
+        Assertions.assertThat(result)
+                .asString()
+                .contains("two.txt");
+    }
+
+    @Test
+    public void givenAbsoluteURIs_whenRelativizeUriOneParentToUriThree_thenAbsoluteIsReturned() {
+        URI result = pathOne.getParent().toUri().relativize(uriThree);
+
+        Assertions.assertThat(result)
+                .asString()
+                .contains("/baeldung/foo/three.txt");
+    }
+
+}

core-java-modules/pom.xml

@@ -67,6 +67,7 @@
         <module>core-java-io-3</module>
         <module>core-java-io-4</module>
         <module>core-java-io-apis</module>
+        <module>core-java-io-apis-2</module>
         <module>core-java-io-conversions</module>
         <module>core-java-jar</module>
         <module>core-java-jndi</module>