implement method to trim Entries

src/main/java/com/reandroid/arsc/array/TypeBlockArray.java

@@ -45,6 +45,14 @@ public class TypeBlockArray extends BlockArray<TypeBlock>
     public void sort(){
         sort(this);
     }
+    public boolean removeNullEntries(int startId){
+        boolean result = true;
+        for(TypeBlock typeBlock:listItems()){
+            boolean removed = typeBlock.removeNullEntries(startId);
+            result = result && removed;
+        }
+        return result;
+    }
     public void removeEmptyBlocks(){
         List<TypeBlock> allTypes=new ArrayList<>(listItems());
         boolean foundEmpty=false;

src/main/java/com/reandroid/arsc/base/BlockArray.java

@@ -24,6 +24,34 @@ public abstract class BlockArray<T extends Block> extends BlockContainer<T> impl
         elementData= newInstance(0);
     }
 
+    public void removeAllNull(int start){
+        removeAll(start, true);
+    }
+    public void removeAll(int start){
+        removeAll(start, false);
+    }
+    private void removeAll(int start, boolean check_null){
+        List<T> removeList = subList(start);
+        if(removeList.size()==0 || (check_null && !isAllNull(removeList))){
+            return;
+        }
+        T[] itemArray = this.elementData;
+        for(T item:removeList){
+            if(item==null){
+                continue;
+            }
+            if(!item.isNull()){
+                item.setNull(true);
+            }
+            int index = item.getIndex();
+            if(index>=0 && itemArray[index]==item){
+                item.setIndex(-1);
+                item.setParent(null);
+                itemArray[index] = null;
+            }
+        }
+        setChildesCount(start);
+    }
     public List<T> subList(int start){
         return subList(start, -1);
     }
@@ -363,6 +391,15 @@ public abstract class BlockArray<T extends Block> extends BlockContainer<T> impl
         return "count="+ childesCount();
     }
 
+    public static boolean isAllNull(Collection<? extends Block> itemsList){
+        for(Block item:itemsList){
+            if(item!=null && !item.isNull()){
+                return false;
+            }
+        }
+        return true;
+    }
+
     private class BlockIterator implements Iterator<T> {
         private int mCursor;
         private final int mMaxSize;

src/main/java/com/reandroid/arsc/chunk/TypeBlock.java

@@ -53,6 +53,12 @@ public class TypeBlock extends Chunk<TypeHeader>
         addChild(entryOffsets);
         addChild(mEntryArray);
     }
+    public boolean removeNullEntries(int startId){
+        startId = 0x0000ffff & startId;
+        EntryArray entryArray = getEntryArray();
+        entryArray.removeAllNull(startId);
+        return entryArray.childesCount() == startId;
+    }
     public PackageBlock getPackageBlock(){
         SpecTypePair specTypePair = getParent(SpecTypePair.class);
         if(specTypePair!=null){

src/main/java/com/reandroid/arsc/container/SpecTypePair.java

@@ -65,6 +65,15 @@ public class SpecTypePair extends BlockContainer<Block>
     public void sortTypes(){
         getTypeBlockArray().sort();
     }
+    public boolean removeNullEntries(int startId){
+        startId = 0x0000ffff & startId;
+        boolean removed = getTypeBlockArray().removeNullEntries(startId);
+        if(!removed){
+            return false;
+        }
+        getSpecBlock().setEntryCount(startId);
+        return true;
+    }
     public void removeEmptyTypeBlocks(){
         getTypeBlockArray().removeEmptyBlocks();
     }

src/main/java/com/reandroid/arsc/item/ReferenceBlock.java

@@ -35,4 +35,8 @@ public class ReferenceBlock<T extends Block> implements ReferenceItem{
     public int get() {
         return BlockItem.getInteger(this.block.getBytes(), this.offset);
     }
+    @Override
+    public String toString(){
+        return get()+":"+this.block;
+    }
 }