Android实战简易教程（GridView动态添加Item）

本例子实现在GridView的最后显示一个增加图片，点击图片动态增加内容item。

1.main.xml:

 <RelativeLayout 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" >

     <GridView
         android:id="@+id/gv_test"
         android:numColumns="3"
         android:layout_width="match_parent"
         android:layout_height="match_parent" />

 RelativeLayout>

2.grid_item.xml：

 xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:orientation="vertical" >

     <ImageView
         android:id="@+id/item"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content" />

 LinearLayout>

3.GridViewAdapter.java:

 package com.yayun.gridviewdemo;

 import java.util.List;

 import android.content.Context;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.BaseAdapter;
 import android.widget.ImageView;

 public class GridViewAdapter extends BaseAdapter {
     private Context context;
     private List list;
     LayoutInflater layoutInflater;
     private ImageView mImageView;

     public GridViewAdapter(Context context, List list) {
         this.context = context;
         this.list = list;
         layoutInflater = LayoutInflater.from(context);
     }

     @Override
     public int getCount() {
         return list.size()+1;//注意此处
     }

     @Override
     public Object getItem(int position) {
         return list.get(position);
     }

     @Override
     public long getItemId(int position) {
         return position;
     }

     @Override
     public View getView(int position, View convertView, ViewGroup parent) {

         convertView = layoutInflater.inflate(R.layout.grid_item, null);
         mImageView = (ImageView) convertView.findViewById(R.id.item);
         if (position < list.size()) {
             mImageView.setBackgroundResource(list.get(position));
         }else{
             mImageView.setBackgroundResource(R.drawable.pic3);//最后一个显示加号图片
         }
         return convertView;
     }

 }

4.MainActivity.java:

 package com.yayun.gridviewdemo;

 import java.util.ArrayList;
 import java.util.List;

 import android.os.Bundle;
 import android.support.v7.app.ActionBarActivity;
 import android.view.View;
 import android.widget.AdapterView;
 import android.widget.AdapterView.OnItemClickListener;
 import android.widget.GridView;
 import android.widget.Toast;

 public class MainActivity extends ActionBarActivity {
     private List mDatas;
 private GridView mGridView;
 private GridViewAdapter adapter;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         mGridView=(GridView) findViewById(R.id.gv_test);

         initDatas();
         adapter=new GridViewAdapter(MainActivity.this,mDatas);
         mGridView.setAdapter(adapter);
         mGridView.setOnItemClickListener(new OnItemClickListener() {

             @Override
             public void onItemClick(AdapterView parent, View view,
                     int position, long id) {
                 if(position==parent.getChildCount()-1){
                     mDatas.add(R.drawable.pic1);
                     Toast.makeText(MainActivity.this, "您点击了添加", 1).show();
                     adapter=new GridViewAdapter(MainActivity.this, mDatas);
                     mGridView.setAdapter(adapter);
                     adapter.notifyDataSetChanged();
                 }

             }
         });

     }
     private void initDatas() {
         mDatas=new ArrayList<>();
         mDatas.add(R.drawable.pic1);
         mDatas.add(R.drawable.pic1);
         mDatas.add(R.drawable.pic1);
         mDatas.add(R.drawable.pic1);
         mDatas.add(R.drawable.pic1);

     }


     }

5.运行项目：