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Android提高十七篇之多级树形菜单的实现

2011-01-10

   在Android里要实现树形菜单,都是用ExpandableList(也有高手自己继承ListView或者LinearLayout来做),但是ExpandableList一般只能实现2级树形菜单......本文也依然使用ExpandableList,但是要实现的是3级树形菜单。本文程序

Android里要实现树形菜单,都是用ExpandableList(也有高手自己继承ListView或者LinearLayout来做),但是ExpandableList一般只能实现2级树形菜单......本文也依然使用ExpandableList,但是要实现的是3级树形菜单。本文程序运行效果图:

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当用BaseExpandableListAdapter来实现二级树形菜单时,父项(getGroupView())和子项(getChildView())都是使用TextView。当要实现三级树形菜单时,子项(getChildView())就必须使用ExpandableList了.......另外还要定义结构体来方便调用三级树形的数据,二级树形菜单可以用如下:

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static public class TreeNode{
Object parent;
List<Object> childs=new ArrayList<Object>();
}
static public class TreeNode{
Object parent;
List<Object> childs=new ArrayList<Object>();
}

三级树形菜单可以用如下,子项是二级树形菜单的结构体:

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static public class SuperTreeNode {
Object parent;
//二级树形菜单的结构体
List<TreeViewAdapter.TreeNode> childs = new ArrayList<TreeViewAdapter.TreeNode>();
}
static public class SuperTreeNode {
Object parent;
//二级树形菜单的结构体
List<TreeViewAdapter.TreeNode> childs = new ArrayList<TreeViewAdapter.TreeNode>();
}

实现三级树形菜单有两点要注意的:

1、第二级也是个树形菜单,因此必须在第二级项目展开/回收时设置足够的空间来完全显示二级树形菜单;

2、在实现三级树形菜单时,发现菜单的方法都是用不了(如OnChildClickListener、OnGroupClickListener等),因此要获得选中的数据就必须在外部定义好回调函数,然后在第二级生成二级树形菜单时回调这个外部函数。

PS:本文在解决No.2关键点的时候,只能取得第三级选中的序号.....而第一,第二级依然无法获取其序号。

main.xml源码如下:

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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<LinearLayout android:id="@+id/LinearLayout01"
android:layout_width="wrap_content" android:layout_height="wrap_content">
<Button android:layout_height="wrap_content" android:text="两层结构"
android:layout_width="160dip" android:id="@+id/btnNormal"></Button>
<Button android:layout_height="wrap_content" android:text="三层结构"
android:layout_width="160dip" android:id="@+id/btnSuper"></Button>
</LinearLayout>
<ExpandableListView android:id="@+id/ExpandableListView01"
android:layout_width="fill_parent" android:layout_height="fill_parent"></ExpandableListView>
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<LinearLayout android:id="@+id/LinearLayout01"
android:layout_width="wrap_content" android:layout_height="wrap_content">
<Button android:layout_height="wrap_content" android:text="两层结构"
android:layout_width="160dip" android:id="@+id/btnNormal"></Button>
<Button android:layout_height="wrap_content" android:text="三层结构"
android:layout_width="160dip" android:id="@+id/btnSuper"></Button>
</LinearLayout>
<ExpandableListView android:id="@+id/ExpandableListView01"
android:layout_width="fill_parent" android:layout_height="fill_parent"></ExpandableListView>
</LinearLayout>

testExpandableList.java是主类,调用其他工具类,源码如下:

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package com.testExpandableList;


import java.util.List;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ExpandableListView;
import android.widget.ExpandableListView.OnChildClickListener;
import android.widget.Toast;

public class testExpandableList extends Activity {
/** Called when the activity is first created. */
ExpandableListView expandableList;
TreeViewAdapter adapter;
SuperTreeViewAdapter superAdapter;
Button btnNormal,btnSuper;
// Sample data set. children[i] contains the children (String[]) for groups[i].
public String[] groups = { "xxxx好友", "xxxx同学", "xxxxx女人"};
public String[][] child= {
{ "A君", "B君", "C君", "D君" },
{ "同学甲", "同学乙", "同学丙"},
{ "御姐", "萝莉" }
};

public String[] parent = { "xxxx好友", "xxxx同学"};
public String[][][] child_grandson= {
{{"A君"},
{"AA","AAA"}},
{{"B君"},
{"BBB","BBBB","BBBBB"}},
{{"C君"},
{"CCC","CCCC"}},
{{"D君"},
{"DDD","DDDD","DDDDD"}},
};

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

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