Android实战简易教程-第二十一枪（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<Integer> list;
  LayoutInflater layoutInflater;
  private ImageView mImageView;

  public GridViewAdapter(Context context, List<Integer> 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<Integer> 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：

参考上一篇博客的删除，可以实现动态增加和动态删除功能。

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