Allow ListPreference summary to use entry

Currently when ListPreferences are used in a PreferenceActivity, the summary
values are set to the same as the current index in mEntryValue. This patch
adds the ability for a string substitution to be used in the summary
which points to the corresponding entry in mEntries to aid in
localization.

For example a preference may be named "color" with the following attributes
in the locale "de" (German):

mEntryValues = { "red", "green", "blue" }
mEntries = { "rot", "grün", "blau" }
mSummary = "Die Farbe ist %1$s."

getSummary() returns "Die Farbe ist grün."

Change-Id: Iea169ac3d1c9d6290d853fc7c67a7c4c8a11bb90

core/java/android/preference/ListPreference.java

@@ -39,6 +39,7 @@ public class ListPreference extends DialogPreference {
     private CharSequence[] mEntries;
     private CharSequence[] mEntryValues;
     private String mValue;
+    private String mSummary;
     private int mClickedDialogEntryIndex;
     
     public ListPreference(Context context, AttributeSet attrs) {
@@ -49,8 +50,16 @@ public class ListPreference extends DialogPreference {
         mEntries = a.getTextArray(com.android.internal.R.styleable.ListPreference_entries);
         mEntryValues = a.getTextArray(com.android.internal.R.styleable.ListPreference_entryValues);
         a.recycle();
+
+        /* Retrieve the Preference summary attribute since it's private
+         * in the Preference class.
+         */
+        a = context.obtainStyledAttributes(attrs,
+                com.android.internal.R.styleable.Preference, 0, 0);
+        mSummary = a.getString(com.android.internal.R.styleable.Preference_summary);
+        a.recycle();
     }
-    
+
     public ListPreference(Context context) {
         this(context, null);
     }
@@ -126,6 +135,43 @@ public class ListPreference extends DialogPreference {
         persistString(value);
     }
 
+    /**
+     * Returns the summary of this ListPreference. If the summary
+     * has a {@linkplain java.lang.String#format String formatting}
+     * marker in it (i.e. "%s" or "%1$s"), then the current entry
+     * value will be substituted in its place.
+     *
+     * @return the summary with appropriate string substitution
+     */
+    @Override
+    public CharSequence getSummary() {
+        final CharSequence entry = getEntry();
+        if (mSummary == null || entry == null) {
+            return super.getSummary();
+        } else {
+            return String.format(mSummary, entry);
+        }
+    }
+
+    /**
+     * Sets the summary for this Preference with a CharSequence.
+     * If the summary has a
+     * {@linkplain java.lang.String#format String formatting}
+     * marker in it (i.e. "%s" or "%1$s"), then the current entry
+     * value will be substituted in its place when it's retrieved.
+     *
+     * @param summary The summary for the preference.
+     */
+    @Override
+    public void setSummary(CharSequence summary) {
+        super.setSummary(summary);
+        if (summary == null && mSummary != null) {
+            mSummary = null;
+        } else if (summary != null && !summary.equals(mSummary)) {
+            mSummary = summary.toString();
+        }
+    }
+
     /**
      * Sets the value to the given index from the entry values.
      * 

core/tests/coretests/src/android/preference/ListPreferenceTest.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.preference;
+
+import android.preference.ListPreference;
+import android.test.AndroidTestCase;
+
+public class ListPreferenceTest extends AndroidTestCase {
+    public void testListPreferenceSummaryFromEntries() {
+        String[] entries = { "one", "two", "three" };
+        String[] entryValues = { "1" , "2", "3" };
+        ListPreference lp = new ListPreference(getContext());
+        lp.setEntries(entries);
+        lp.setEntryValues(entryValues);
+
+        lp.setValue(entryValues[1]);
+        assertTrue(lp.getSummary() == null);
+
+        lp.setSummary("%1$s");
+        assertEquals(entries[1], lp.getSummary());
+
+        lp.setValue(entryValues[2]);
+        assertEquals(entries[2], lp.getSummary());
+
+        lp.setSummary(null);
+        assertTrue(lp.getSummary() == null);
+
+        lp.setSummary("The color is %1$s");
+        assertEquals("The color is " + entries[2], lp.getSummary());
+    }
+}