fix: discard old items in recent activities list

.gitignore

@@ -5,3 +5,6 @@ build
 captures
 local.properties
 gradle/wrapper/gradle-wrapper.jar
+**/.project
+**/.settings
+**/.classpath

app/build.gradle

@@ -26,5 +26,7 @@ dependencies {
     })
     compile 'com.android.support:appcompat-v7:25.2.0'
     //compile 'com.android.support.constraint:constraint-layout:1.1.3'
+    //testCompile 'org.testng:testng:7.1.0'
     testCompile 'junit:junit:4.12'
+    testCompile 'org.assertj:assertj-core:3.16.1'
 }

app/src/main/java/by/yauhenl/gardine/RecentActivities.java → app/src/main/java/by/yauhenl/gardine/DiscardingStack.java

@@ -5,17 +5,23 @@
 import java.util.Iterator;
 import java.util.LinkedHashSet;
 
-public class RecentActivities {
+/**
+ * Stack (FILO) of unique elements.
+ * All elements over limit are dropped.
+ * Adding the same element several times moves it on top of the stack.
+ * @param <T>
+ */
+public class DiscardingStack<T> {
 
     private final int limit;
-    private LinkedHashSet<App> apps;
+    private LinkedHashSet<T> apps;
 
-    public RecentActivities(int limit) {
+    public DiscardingStack(int limit) {
         this.limit = limit;
         this.apps = new LinkedHashSet<>();
     }
 
-    public void add(App app) {
+    public void add(T app) {
         if(apps.contains(app)) {
             apps.remove(app);
         } else {
@@ -24,9 +30,9 @@ public void add(App app) {
         apps.add(app);
     }
 
-    public Collection<App> getAll() {
-        ArrayDeque<App> reversed =  new ArrayDeque<>();
-        for (App a : this.apps) {
+    public Collection<T> getAll() {
+        ArrayDeque<T> reversed =  new ArrayDeque<>();
+        for (T a : this.apps) {
             reversed.push(a);
         }
         return reversed;
@@ -36,10 +42,10 @@ private void truncateSize(int limit) {
         if(apps.size() < limit) {
             return;
         }
-        Iterator<App> iter = apps.iterator();
-        for (int i = 0; iter.hasNext(); i++) {
+        Iterator<T> iter = apps.iterator();
+        for (int i = apps.size(); iter.hasNext(); i--) {
             iter.next();
-            if(i >= limit) {
+            if(i > limit) {
                 iter.remove();
             }
         }

app/src/main/java/by/yauhenl/gardine/GardineWidgetService.java

@@ -38,13 +38,13 @@ public class GardineWidgetService extends AccessibilityService {
     private WindowManager windowManager;
     private View gardine;
     private ArrayList<App> recentApps;
-    private RecentActivities recentActivities;
+    private DiscardingStack<App> recentActivities;
     private ArrayAdapter<App> recentAppsAdapter;
     private Vibrator vibrator;
 
     public GardineWidgetService() {
         this.recentApps = new ArrayList<>();
-        this.recentActivities = new RecentActivities(MAX_ITEMS);
+        this.recentActivities = new DiscardingStack<>(MAX_ITEMS);
     }
 
     @Override

app/src/test/java/by/yauhenl/gardine/DiscardingStackTest.java

@@ -0,0 +1,39 @@
+package by.yauhenl.gardine;
+
+import org.junit.Test;
+import static org.assertj.core.api.Java6Assertions.*;
+
+public class RecentActivitiesTest {
+
+    private static final String a = "a", b = "b", c = "c", d = "d";
+
+    @Test
+    public void singleElement_noTruncation() {
+        DiscardingStack<String> ra = new DiscardingStack<>(3);
+        ra.add(a);
+        ra.add(a);
+        ra.add(a);
+        assertThat(ra.getAll()).containsOnly(a);
+    }
+
+    @Test
+    public void twoElements_noTruncation() {
+        DiscardingStack<String> ra = new DiscardingStack<>(3);
+        ra.add(a);
+        ra.add(b);
+        ra.add(a);
+        assertThat(ra.getAll()).containsOnly(a, b);
+    }
+
+    @Test
+    public void threeElements_withTruncation() {
+        DiscardingStack<String> ra = new DiscardingStack<>(3);
+        ra.add(a);
+        ra.add(b);
+        ra.add(c);
+        ra.add(d);
+        assertThat(ra.getAll()).containsOnly(b, c, d);
+    }
+
+
+}