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Commit 7bd7f0d1 authored by Steve McKay's avatar Steve McKay
Browse files

Guard against NPEs in pre-init selection helper. 

Some input events may arrive in such an order that DocsSelectionHelper
gets called before it's `reset` method. In those cases we're
seeing an NPE.

BUG: 69306667
Test: Added new basic.
Change-Id: I0e6c73861a7cd7b3d65512e2822b7854622e11ab
parent 5eecb743

src/com/android/documentsui/DocsSelectionHelper.java

+99 −1
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ import android.support.v7.widget.RecyclerView; 


import com.android.documentsui.selection.DefaultSelectionHelper;

import com.android.documentsui.selection.DefaultSelectionHelper.SelectionMode;

import com.android.documentsui.selection.MutableSelection;

import com.android.documentsui.selection.Selection;

import com.android.documentsui.selection.SelectionHelper;
@@ -37,7 +38,10 @@ public final class DocsSelectionHelper extends SelectionHelper { 
    private final DelegateFactory mFactory;

    private final @SelectionMode int mSelectionMode;



    private @Nullable SelectionHelper mDelegate;

    // initialize to a dummy object incase we get some input

    // event drive calls before we're properly initialized.

    // See: b/69306667.

    private SelectionHelper mDelegate = new DummySelectionHelper();



    @VisibleForTesting

    DocsSelectionHelper(DelegateFactory factory, @SelectionMode int mode) {
@@ -188,4 +192,98 @@ public final class DocsSelectionHelper extends SelectionHelper { 
            return new DefaultSelectionHelper(mode, adapter, stableIds, canSetState);

        }

    }



    /**

     * A dummy SelectHelper used by DocsSelectionHelper before a real

     * SelectionHelper has been initialized by DirectoryFragment.

     */

    private static final class DummySelectionHelper extends SelectionHelper {



        @Override

        public void addObserver(SelectionObserver listener) {

        }



        @Override

        public boolean hasSelection() {

            return false;

        }



        @Override

        public Selection getSelection() {

            return new MutableSelection();

        }



        @Override

        public void copySelection(Selection dest) {

        }



        @Override

        public boolean isSelected(String id) {

            return false;

        }



        @VisibleForTesting

        public void replaceSelection(Iterable<String> ids) {

        }



        @Override

        public void restoreSelection(Selection other) {

        }



        @Override

        public boolean setItemsSelected(Iterable<String> ids, boolean selected) {

            return false;

        }



        @Override

        public void clearSelection() {

        }



        @Override

        public boolean select(String modelId) {

            return false;

        }



        @Override

        public boolean deselect(String modelId) {

            return false;

        }



        @Override

        public void startRange(int pos) {

        }



        @Override

        public void extendRange(int pos) {

        }



        @Override

        public void extendProvisionalRange(int pos) {

        }



        @Override

        public void clearProvisionalSelection() {

        }



        @Override

        public void setProvisionalSelection(Set<String> newSelection) {

        }



        @Override

        public void mergeProvisionalSelection() {

        }



        @Override

        public void endRange() {

        }



        @Override

        public boolean isRangeActive() {

            return false;

        }



        @Override

        public void anchorRange(int position) {

        }

    }

}

tests/unit/com/android/documentsui/DocsSelectionHelperTest.java

+9 −0
Original line number Diff line number Diff line
@@ -17,6 +17,8 @@ 
package com.android.documentsui;



import static org.junit.Assert.assertEquals;

import static org.junit.Assert.assertFalse;

import static org.junit.Assert.assertNotNull;

import static org.junit.Assert.assertTrue;



import android.support.test.filters.SmallTest;
@@ -71,6 +73,13 @@ public class DocsSelectionHelperTest { 
        mSelectionMgr = new DocsSelectionHelper(mFactory, DefaultSelectionHelper.MODE_MULTIPLE);

    }



    @Test

    public void testCallableBeforeReset() {

        mSelectionMgr.hasSelection();

        assertNotNull(mSelectionMgr.getSelection());

        assertFalse(mSelectionMgr.isSelected("poodle"));

    }



    @Test

    public void testReset_CreatesNewInstances() {

        mSelectionMgr.reset(null, null, null);  // nulls are passed to factory. We ignore.