今天带来的是两列并排ListView关联滑动,这里面有两个知识点:1、两个ListView如何并列显示。2、如何关联滑动。
第一个问题,好像我之前的博客提到过,就是让ListView的width有wrap_content的能力,可以参考我的另一篇博客《并排ListView——仿京东分类列表》。
今天的重点在第二个问题上,如何让两个ListView联动起来。
虽然,重点在第二个问题上,但是,任何事都得一步步的来,首先,我们要先让ListView的width有wrap_content的能力。
public class RelationListView extends ListView { private RelationListView mListView; public RelationListView(Context context, AttributeSet attrs) { this(context, attrs, 0); } public RelationListView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); int width = 0; int height = getMeasuredHeight(); int widthMode = MeasureSpec.getMode(widthMeasureSpec); int widthSize = MeasureSpec.getSize(widthMeasureSpec); if(widthMode == MeasureSpec.EXACTLY) { width = widthSize; }else if(widthMode == MeasureSpec.AT_MOST) { final int childCount = getChildCount(); for(int i=0;i<childCount;i++) { View item = getChildAt(i); measureChild(item, widthMeasureSpec, heightMeasureSpec); width = Math.max(width, item.getMeasuredWidth()); } } setMeasuredDimension(width, height); } }
可以看到,要让ListView的width有wrap_content的能力,主要是去重写ListView的onMeasure方法,这部分内容这里不多说了,可以去看我之前的那篇博客。可以看到,我们主要是改变了width的值,让width的值等于最宽的那个item的宽度。
继续往下走,如何让两个ListView关联,肯定是要保存另一个ListView的实例,才能去操作它,细心的朋友,可能看到在RelationListView中有一个成员变量:
private RelationListView mListView;
怎么去设置它的值呢? 当然是自定义一个方法了:
public void setRelatedListView(RelationListView listView) { mListView = listView; }
我们在外部通过调用该方法来声明,哪个ListView要与该ListView联动。
如何控制联动? 首先我们要知道当前ListView滑动了,我选择了onTouchEvent, 这个方法有个参数MotionEvent 我们直接将这个参数传给要联动的那个ListView的onTouchEvent就ok,直接在onTouchEvent中传吗? 当然不是,那样就造成死循环了。
来看代码:
public void onTouch(MotionEvent ev) { super.onTouchEvent(ev); } @Override public boolean onTouchEvent(MotionEvent ev) { if(null != mListView) { mListView.onTouch(ev); } return super.onTouchEvent(ev); }
我是定义了一个onTouch方法方法,然后在onTouchEvent中调用该方法。 有什么不一样吗? 在onTouch中,我们直接调用父类的onTouchEvent而不是重写的那个onTouchEvent,这样就避免了死循环。
来使用一下吧, 布局文件:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" android:orientation="horizontal" tools:context=".MainActivity" > <org.loader.relationlistview.RelationListView android:id="@+id/listView1" android:layout_width="wrap_content" android:layout_height="wrap_content" /> <org.loader.relationlistview.RelationListView android:id="@+id/listView2" android:layout_width="wrap_content" android:layout_height="wrap_content" /> </LinearLayout>
没有联动的情况:
public class MainActivity extends Activity { private RelationListView mListView1; private RelationListView mListView2; private String[] mData1 = new String[] { "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1", "listView1" }; private String[] mData2 = new String[] { "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2", "ListView2" }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mListView1 = (RelationListView) findViewById(R.id.listView1); mListView2 = (RelationListView) findViewById(R.id.listView2); mListView1.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, mData1)); mListView2.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, mData2)); } }
看看效果,是不是两列ListView了,第一个问题已经实现了。
再来看看单向联动,ok,添加一行代码:
mListView1.setRelatedListView(mListView2);
是不是很爽? 相信你已经知道双向联动该如何做了, 对,再添加一行代码:
mListView2.setRelatedListView(mListView1);
这样就实现了ListView的双向联动。
最后是所有的代码下载地址:http://git.oschina.net/qibin/RelationListView