android_calculator-47: Remember last used tab in vars, functions etc

src/main/java/org/solovyev/android/calculator/about/CalculatorAboutTabActivity.java

@@ -11,6 +11,7 @@ import android.widget.TabHost;
 import org.jetbrains.annotations.Nullable;
 import org.solovyev.android.AndroidUtils;
 import org.solovyev.android.calculator.R;
+import org.solovyev.android.view.LastTabSaver;
 
 /**
  * User: serso
@@ -19,6 +20,9 @@ import org.solovyev.android.calculator.R;
  */
 public class CalculatorAboutTabActivity extends TabActivity {
 
+	@Nullable
+	private LastTabSaver lastTabSaver;
+
 	@Override
 	public void onCreate(@Nullable Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
@@ -30,7 +34,17 @@ public class CalculatorAboutTabActivity extends TabActivity {
 		AndroidUtils.addTab(this, tabHost, "about", R.string.c_about, CalculatorAboutActivity.class);
 		AndroidUtils.addTab(this, tabHost, "release_notes", R.string.c_release_notes, CalculatorReleaseNotesActivity.class);
 
-		tabHost.setCurrentTab(0);
+		lastTabSaver = new LastTabSaver(this, "about");
+
 		AndroidUtils.centerAndWrapTabsFor(tabHost);
 	}
+
+	@Override
+	protected void onDestroy() {
+		if ( this.lastTabSaver != null ) {
+			this.lastTabSaver.destroy();
+		}
+
+		super.onDestroy();
+	}
 }

src/main/java/org/solovyev/android/calculator/help/CalculatorHelpTabActivity.java

@@ -15,6 +15,7 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.solovyev.android.AndroidUtils;
 import org.solovyev.android.calculator.R;
+import org.solovyev.android.view.LastTabSaver;
 
 /**
  * User: serso
@@ -23,6 +24,9 @@ import org.solovyev.android.calculator.R;
  */
 public class CalculatorHelpTabActivity extends TabActivity {
 
+	@Nullable
+	private LastTabSaver lastTabSaver;
+
 	@Override
 	public void onCreate(@Nullable Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
@@ -35,7 +39,7 @@ public class CalculatorHelpTabActivity extends TabActivity {
 		createTab(tabHost, "hints", R.string.c_hints, HelpHintsActivity.class);
 		createTab(tabHost, "screens", R.string.c_screens, HelpScreensActivity.class);
 
-		tabHost.setCurrentTab(0);
+		this.lastTabSaver = new LastTabSaver(this, "faq");
 
 		AndroidUtils.centerAndWrapTabsFor(tabHost);
 	}
@@ -54,4 +58,13 @@ public class CalculatorHelpTabActivity extends TabActivity {
 
 		tabHost.addTab(spec);
 	}
+
+	@Override
+	protected void onDestroy() {
+		if (this.lastTabSaver != null) {
+			this.lastTabSaver.destroy();
+		}
+
+		super.onDestroy();
+	}
 }

src/main/java/org/solovyev/android/calculator/history/CalculatorHistoryTabActivity.java

@@ -12,6 +12,7 @@ import android.widget.TabHost;
 import org.jetbrains.annotations.Nullable;
 import org.solovyev.android.AndroidUtils;
 import org.solovyev.android.calculator.R;
+import org.solovyev.android.view.LastTabSaver;
 
 /**
  * User: serso
@@ -20,6 +21,9 @@ import org.solovyev.android.calculator.R;
  */
 public class CalculatorHistoryTabActivity extends TabActivity {
 
+	@Nullable
+	private LastTabSaver lastTabSaver;
+
 	@Override
 	public void onCreate(@Nullable Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
@@ -31,8 +35,16 @@ public class CalculatorHistoryTabActivity extends TabActivity {
 		AndroidUtils.addTab(this, tabHost, "saved_history", R.string.c_saved_history, SavedHistoryActivityTab.class);
 		AndroidUtils.addTab(this, tabHost, "history", R.string.c_history, HistoryActivityTab.class);
 
-		tabHost.setCurrentTab(0);
+		this.lastTabSaver = new LastTabSaver(this, "saved_history");
 
         AndroidUtils.centerAndWrapTabsFor(tabHost);
 	}
+
+	@Override
+	protected void onDestroy() {
+		if ( this.lastTabSaver != null ) {
+			this.lastTabSaver.destroy();
+		}
+		super.onDestroy();
+	}
 }

src/main/java/org/solovyev/android/calculator/math/edit/CalculatorFunctionsTabActivity.java

@@ -13,6 +13,7 @@ import org.jetbrains.annotations.Nullable;
 import org.solovyev.android.AndroidUtils;
 import org.solovyev.android.calculator.R;
 import org.solovyev.android.calculator.model.AndroidFunctionsMathRegistry;
+import org.solovyev.android.view.LastTabSaver;
 
 /**
  * User: serso
@@ -21,6 +22,9 @@ import org.solovyev.android.calculator.model.AndroidFunctionsMathRegistry;
  */
 public class CalculatorFunctionsTabActivity extends TabActivity {
 
+	@Nullable
+	private LastTabSaver lastTabSaver;
+
     @Override
     public void onCreate(@Nullable Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -33,7 +37,16 @@ public class CalculatorFunctionsTabActivity extends TabActivity {
             AbstractMathEntityListActivity.createTab(this, tabHost, category.name(), category.name(), category.getCaptionId(), CalculatorFunctionsActivity.class, null);
         }
 
+		this.lastTabSaver = new LastTabSaver(this, AndroidFunctionsMathRegistry.Category.common.name());
+
         AndroidUtils.centerAndWrapTabsFor(tabHost);
     }
 
+	@Override
+	protected void onDestroy() {
+		if (lastTabSaver != null) {
+			this.lastTabSaver.destroy();
+		}
+		super.onDestroy();
+	}
 }

src/main/java/org/solovyev/android/calculator/math/edit/CalculatorVarsTabActivity.java

@@ -13,6 +13,7 @@ import org.jetbrains.annotations.Nullable;
 import org.solovyev.android.AndroidUtils;
 import org.solovyev.android.calculator.R;
 import org.solovyev.android.calculator.model.VarCategory;
+import org.solovyev.android.view.LastTabSaver;
 
 /**
  * User: serso
@@ -21,6 +22,9 @@ import org.solovyev.android.calculator.model.VarCategory;
  */
 public class CalculatorVarsTabActivity extends TabActivity {
 
+	@Nullable
+	private LastTabSaver lastTabSaver;
+
     @Override
     public void onCreate(@Nullable Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -37,8 +41,16 @@ public class CalculatorVarsTabActivity extends TabActivity {
             }
         }
 
-        tabHost.setCurrentTab(0);
+		this.lastTabSaver = new LastTabSaver(this, VarCategory.my.name());
+
         AndroidUtils.centerAndWrapTabsFor(tabHost);
     }
 
+	@Override
+	protected void onDestroy() {
+		if (lastTabSaver != null) {
+			lastTabSaver.destroy();
+		}
+		super.onDestroy();
+	}
 }

src/main/java/org/solovyev/android/view/LastTabSaver.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2009-2012. Created by serso aka se.solovyev.
+ * For more information, please, contact se.solovyev@gmail.com
+ * or visit http://se.solovyev.org
+ */
+
+package org.solovyev.android.view;
+
+import android.app.TabActivity;
+import android.preference.PreferenceManager;
+import android.widget.TabHost;
+import org.jetbrains.annotations.NotNull;
+import org.solovyev.android.view.prefs.StringPreference;
+
+/**
+ * User: serso
+ * Date: 1/9/12
+ * Time: 6:17 PM
+ */
+public class LastTabSaver implements TabHost.OnTabChangeListener {
+
+	private static final String LAST_OPENED_TAB_P_KEY = "last_opened_tab_";
+
+	@NotNull
+	private final StringPreference<String> preference;
+
+	@NotNull
+	private final TabActivity tabActivity;
+
+	public LastTabSaver(@NotNull TabActivity tabActivity, @NotNull String defaultTabId) {
+		this.tabActivity = tabActivity;
+		this.preference = StringPreference.newInstance(getPreferenceKey(), defaultTabId);
+
+		final TabHost tabHost = tabActivity.getTabHost();
+		tabHost.setCurrentTabByTag(this.getLastOpenedTabId());
+		tabHost.setOnTabChangedListener(this);
+	}
+
+	public void destroy() {
+		final TabHost tabHost = tabActivity.getTabHost();
+		tabHost.setOnTabChangedListener(null);
+	}
+
+	@Override
+	public void onTabChanged(String tabId) {
+		preference.putPreference(PreferenceManager.getDefaultSharedPreferences(tabActivity), tabId);
+	}
+
+	@NotNull
+	public String getLastOpenedTabId() {
+		return preference.getPreference(PreferenceManager.getDefaultSharedPreferences(tabActivity));
+	}
+
+	@NotNull
+	private String getPreferenceKey() {
+		return LAST_OPENED_TAB_P_KEY + tabActivity.getClass().getName();
+	}
+}