本次的Demo是通过GridView展示一个List，通过2个按钮实现GridView从视觉上的增加和减少。
为了方便增加和减少，本次用的储存结构是List。与String在BaseAdapter一样，只需要更改BaseAdapter的2个基本函数分别是getItem(),getCount()
public Object getItem(int position) {return mad[position];}
public int getCount() {return mad.length;}
这是String的 BaseAdapter
@Override
public Object getItem(int position) {// TODO Auto-generated method stubreturn mList.get(position);}@Overridepublic int getCount() {// TODO Auto-generated method stubreturn mList.size();}
这是List的BaseAdapter
下边放上整个代码
package com.example.onclickgridview;import java.security.acl.LastOwnerException;
import java.util.ArrayList;
import java.util.List;import android.R.integer;
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Adapter;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.ListAdapter;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;public class MainActivity extends Activity {// 作用：
// 1、对于一个没有被载入或者想要动态载入的界面, 都需要使用inflate来载入.
//
// 2、对于一个已经载入的Activity, 就可以使用实现了这个Activiyt的的findViewById方法来获得其中的界面元素. private LayoutInflater mInflater;//创建初始化数据源private String[] mad = {"1","2","3","4","5","6","7","8","9"};private List<String> mList;//声明控件private GridView mGridView;//声明adpterprivate Adapter mAdapter;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);//关联 Button btnAdd = (Button) findViewById(R.id.button1); Button btnDel = (Button) findViewById(R.id.button2); mGridView = (GridView) findViewById(R.id.gridView1); mInflater = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);mList = new ArrayList<String>();for(int i = 0; i<mad.length; i++){mList.add(mad[i]);}//新建BaseAdaptermAdapter = new BaseAdapter() {@Overridepublic View getView(int position, View convertView, ViewGroup parent) {TextView text;ImageView imgview;RelativeLayout rLayout;//初始化时加载页面用到的 if里的东西if (convertView == null) {rLayout = (RelativeLayout) mInflater.inflate(R.layout.new_file, parent, false);} else {rLayout = (RelativeLayout) convertView;}String item = (String) getItem(position);//设置控件取回的数据text = (TextView) rLayout.findViewById(R.id.TextView2);text.setText(item);imgview = (ImageView) rLayout.findViewById(R.id.ImageView1);imgview.setImageResource(R.drawable.ic_launcher);return rLayout;}//本次重点 准确返回数据位置的关键 必须在getItemID设置对的位置选项默认从0开始@Overridepublic long getItemId(int position) {// TODO Auto-generated method stubreturn position;}@Overridepublic Object getItem(int position) {// TODO Auto-generated method stubreturn mList.get(position);}@Overridepublic int getCount() {// TODO Auto-generated method stubreturn mList.size();}};mGridView.setAdapter((ListAdapter) mAdapter);//监听事件 对于按下gridView控件的其中一个做出的响应mGridView.setOnItemClickListener(new OnItemClickListener() {@Overridepublic void onItemClick(AdapterView<?> parent, View view, int position,long id) {Toast.makeText(MainActivity.this, "你选择了" + (position + 1) + " 号图片", Toast.LENGTH_SHORT).show();}});//监听2个按钮btnAdd.setOnClickListener(new Button.OnClickListener(){@Overridepublic void onClick(View v) {//通过对list的长度在选择累计增加的数值int j= mList.size();//这里用到了类型转换String s = Integer.toString(j+1);mList.add(s);mGridView.setAdapter((ListAdapter) mAdapter);}});btnDel.setOnClickListener(new Button.OnClickListener(){@Overridepublic void onClick(View v) {//通过对list的长度在选择累计减少的数值int z= mList.size();//这里用到了类型转换String t = Integer.toString(z);mList.remove(t);mGridView.setAdapter((ListAdapter) mAdapter);}});}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}}
展示效果
按下Add一次
多次按下Add
多次按下Delete