Android之GridView延展

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 stub
	return mList.get(position);
                   }
		
@Override
	public int getCount() {
	// TODO Auto-generated method stub
	return 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adpter
	private Adapter mAdapter;
	
	
	@Override
	protected 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BaseAdapter
	mAdapter = new BaseAdapter() {
		
		@Override
		public 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
		@Override
		public long getItemId(int position) {
			// TODO Auto-generated method stub
			return position;
		}
		
		@Override
		public Object getItem(int position) {
			// TODO Auto-generated method stub
			return mList.get(position);
		}
		
		@Override
		public int getCount() {
			// TODO Auto-generated method stub
			return 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() {

		@Override
		public 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(){

		@Override
		public 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(){

		@Override
		public 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);
		}
		
		
		
		
	});
	
	
	
	
	
	
	}
	@Override
	public 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