Use soft references to cache result lists from history.

1 files changed, 20 insertions, 2 deletions

diff --git a/src/org/madore/android/unicodeMap/UnicodeMapActivity.java b/src/org/madore/android/unicodeMap/UnicodeMapActivity.java
index 687493e..e633006 100644
--- a/src/org/madore/android/unicodeMap/UnicodeMapActivity.java
+++ b/src/org/madore/android/unicodeMap/UnicodeMapActivity.java
@@ -1,5 +1,6 @@
 package org.madore.android.unicodeMap;
 
+import java.lang.ref.SoftReference;
 import java.util.Arrays;
 import java.util.List;
 import java.util.ArrayList;
@@ -30,8 +31,18 @@ public final class UnicodeMapActivity extends ListActivity {
 
     protected static abstract class Display {
 	protected String title;
+	protected SoftReference<List<UnicodeDisplayable>> listCacheRef;
 	public Display(String title) { this.title = title; }
 	public final String getTitle() { return this.title; }
+	public void setListCache(List<UnicodeDisplayable> list) {
+	    this.listCacheRef = new SoftReference<List<UnicodeDisplayable>>(list);
+	}
+	public List<UnicodeDisplayable> getListCache() {
+	    if ( this.listCacheRef != null )
+		return this.listCacheRef.get();
+	    else
+		return null;
+	}
     }
     protected static class RootDisplay extends Display {
 	public RootDisplay() { super(null); }
@@ -138,12 +149,17 @@ public final class UnicodeMapActivity extends ListActivity {
 
     protected void doDisplay(Display disp, boolean isNew) {
 	curDisp = disp;
-	List<UnicodeDisplayable> list;
+	List<UnicodeDisplayable> list = disp.getListCache();
 	UnicodeArrayAdapter adapter;
-	if ( disp instanceof RootDisplay ) {
+	if ( list != null ) {
+	    android.util.Log.v("UnicodeMapActivity", "list was retrieved from its cache");
+	    adapter = new UnicodeArrayAdapter(this, list);
+	    setListAdapter(adapter);
+	} else if ( disp instanceof RootDisplay ) {
 	    list = new ArrayList<UnicodeDisplayable>(UnicodeCharacter.Range.values().length);
 	    for ( UnicodeCharacter.Range rng : UnicodeCharacter.Range.values() )
 		list.add(rng);
+	    disp.setListCache(list);
 	    adapter = new UnicodeArrayAdapter(this, list);
 	    setListAdapter(adapter);
 	} else if ( disp instanceof RangeDisplay ) {
@@ -152,6 +168,7 @@ public final class UnicodeMapActivity extends ListActivity {
 	    list = new ArrayList<UnicodeDisplayable>(db.countRange(from,to));
 	    for ( UnicodeCharacter ch : db.getRange(from,to) )
 		list.add(ch);
+	    disp.setListCache(list);
 	    adapter = new UnicodeArrayAdapter(this, list);
 	    setListAdapter(adapter);
 	} else if ( disp instanceof SearchDisplay ) {
@@ -161,6 +178,7 @@ public final class UnicodeMapActivity extends ListActivity {
 	    list = new ArrayList<UnicodeDisplayable>(sizeHint);
 	    for ( UnicodeCharacter ch : db.searchNames(s,limit+1) )
 		list.add(ch);
+	    disp.setListCache(list);
 	    int size = list.size();
 	    ((SearchDisplay)disp).setSizeHint(size);
 	    boolean overflowed = ( size > limit );