Tree as android library.

treedatastructure/build.gradle

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+apply plugin: 'com.android.library'
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-android-extensions'
+android {
+    compileSdkVersion 29
+    buildToolsVersion "29.0.2"
+
+
+    defaultConfig {
+        minSdkVersion 15
+        targetSdkVersion 29
+        versionCode 1
+        versionName "1.0"
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+        consumerProguardFiles 'consumer-rules.pro'
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+
+}
+
+dependencies {
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+    implementation 'androidx.appcompat:appcompat:1.0.2'
+    implementation 'androidx.core:core-ktx:1.0.2'
+    testImplementation 'junit:junit:4.12'
+    androidTestImplementation 'androidx.test.ext:junit:1.1.0'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.1'
+}
+
+ext {
+    PUBLISH_GROUP_ID = 'com.github.adriankuta'
+    PUBLISH_ARTIFACT_ID = 'tree-structure'
+    PUBLISH_VERSION = android.defaultConfig.versionName
+}
+
+apply from: "${rootProject.projectDir}/scripts/publish-mavencentral.gradle"

treedatastructure/proguard-rules.pro

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+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

treedatastructure/src/androidTest/java/com/github/adriankuta/datastructure/tree/ExampleInstrumentedTest.kt

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+package com.github.adriankuta.datastructure.tree
+
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.ext.junit.runners.AndroidJUnit4
+
+import org.junit.Test
+import org.junit.runner.RunWith
+
+import org.junit.Assert.*
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+@RunWith(AndroidJUnit4::class)
+class ExampleInstrumentedTest {
+    @Test
+    fun useAppContext() {
+        // Context of the app under test.
+        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
+        assertEquals("com.github.adriankuta.datastructure.tree.test", appContext.packageName)
+    }
+}

treedatastructure/src/main/AndroidManifest.xml

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+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.github.adriankuta.datastructure.tree" />

treedatastructure/src/main/java/com/github/adriankuta/datastructure/tree/TreeNode.kt

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+package com.github.adriankuta.datastructure.tree
+
+class TreeNode<T>(val value: T) {
+
+    private var parent: TreeNode<T>? = null
+    private val children = mutableListOf<TreeNode<T>>()
+
+    fun addChild(child: TreeNode<T>) {
+        child.parent = this
+        children += child
+    }
+
+    fun removeChild(child: TreeNode<T>): Boolean {
+        if (children.isEmpty()) {
+            return false
+        }
+
+        val nestedChildRemoved = children.map {
+            it.removeChild(child)
+        }.reduce { acc, b -> acc or b }
+
+        return children.remove(child) or nestedChildRemoved
+    }
+
+    fun getParent(): TreeNode<T>? = parent
+
+    fun getChildren(): List<TreeNode<T>> = children
+
+    fun size(): Int {
+        if (children.isEmpty())
+            return 0
+        return children.size +
+                children.sumBy { it.size() }
+
+    }
+
+    fun depth(): Int {
+
+        val childrenMaxDepth = children.map { it.depth() }.max() ?: 0
+        return childrenMaxDepth + 1
+    }
+
+    fun allItems(): List<T> {
+        return children.map { value }
+    }
+
+    override fun toString(): String {
+        val stringBuilder = StringBuilder()
+        print(stringBuilder, "", "")
+        return stringBuilder.toString()
+    }
+
+    private fun print(stringBuilder: StringBuilder, prefix: String, childrenPrefix: String) {
+        stringBuilder.append(prefix)
+        stringBuilder.append(value)
+        stringBuilder.append('\n')
+        val childIterator = children.iterator()
+        while (childIterator.hasNext()) {
+            val node = childIterator.next()
+            if(childIterator.hasNext()) {
+                node.print(stringBuilder, "$childrenPrefix├── ", "$childrenPrefix│   ")
+            } else {
+                node.print(stringBuilder, "$childrenPrefix└── ", "$childrenPrefix    ")
+            }
+        }
+    }
+}

treedatastructure/src/main/res/values/strings.xml

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+<resources>
+    <string name="app_name">Tree Data Structure</string>
+</resources>

treedatastructure/src/test/java/com/github/adriankuta/datastructure/tree/ExampleUnitTest.kt

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+package com.github.adriankuta.datastructure.tree
+
+import org.junit.Test
+
+import org.junit.Assert.*
+
+/**
+ * Example local unit test, which will execute on the development machine (host).
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+class ExampleUnitTest {
+    @Test
+    fun addition_isCorrect() {
+        assertEquals(4, 2 + 2)
+    }
+}