我正在学习 android 技术。我想在单击按钮后在 GridView 中显示图像我使用 BaseAdapter 类。它显示以下错误.java.lang.RuntimeException：无法实例化活动 ComponentInfo{com.example.griddemo/com.example .griddemo.MyAdapter}: java.lang.InstantiationException: com.example.griddemo.MyAdapter. 你能告诉我为什么会出现这个错误以及如何解决它。这是我的完整源代码包 com.example.griddemo；
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.GridView;
import android.widget.ImageView;
import android.support.v4.app.NavUtils;
public class MainActivity extends Activity implements OnClickListener {
Button b1;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
b1=(Button)findViewById(R.id.button1);
b1.setOnClickListener(this);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public void onClick(View v)
{
// TODO Auto-generated method stub
switch(v.getId())
{
case R.id.button1:Intent i =new Intent(MainActivity.this,MyAdapter.class);
startActivity(i);
}
}
}
我的适配器类
package com.example.griddemo;
import android.content.Context;
import android.database.DataSetObserver;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.ListAdapter;
public class MyAdapter extends BaseAdapter
{
Context context;
public String[] imagesvalues=new String[]{"https://lh6.googleusercontent.com/-jZgveEqb6pg/T3R4kXScycI/AAAAAAAAAE0/xQ7CvpfXDzc/s1024/sample_image_01.jpg",
"https://lh4.googleusercontent.com/-K2FMuOozxU0/T3R4lRAiBTI/AAAAAAAAAE8/a3Eh9JvnnzI/s1024/sample_image_02.jpg",
"https://lh5.googleusercontent.com/-SCS5C646rxM/T3R4l7QB6xI/AAAAAAAAAFE/xLcuVv3CUyA/s1024/sample_image_03.jpg",
"https://lh6.googleusercontent.com/-f0NJR6-_Thg/T3R4mNex2wI/AAAAAAAAAFI/45oug4VE8MI/s1024/sample_image_04.jpg",
"https://lh3.googleusercontent.com/-n-xcJmiI0pg/T3R4mkSchHI/AAAAAAAAAFU/EoiNNb7kk3A/s1024/sample_image_05.jpg",
"https://lh3.googleusercontent.com/-X43vAudm7f4/T3R4nGSChJI/AAAAAAAAAFk/3bna6D-2EE8/s1024/sample_image_06.jpg",
"https://lh5.googleusercontent.com/-MpZneqIyjXU/T3R4nuGO1aI/AAAAAAAAAFg/r09OPjLx1ZY/s1024/sample_image_07.jpg",
"https://lh6.googleusercontent.com/-ql3YNfdClJo/T3XvW9apmFI/AAAAAAAAAL4/_6HFDzbahc4/s1024/sample_image_08.jpg",
"https://lh5.googleusercontent.com/-Pxa7eqF4cyc/T3R4oasvPEI/AAAAAAAAAF0/-uYDH92h8LA/s1024/sample_image_09.jpg",
"https://lh4.googleusercontent.com/-Li-rjhFEuaI/T3R4o-VUl4I/AAAAAAAAAF8/5E5XdMnP1oE/s1024/sample_image_10.jpg",
"https://lh5.googleusercontent.com/-_HU4fImgFhA/T3R4pPVIwWI/AAAAAAAAAGA/0RfK_Vkgth4/s1024/sample_image_11.jpg",
"https://lh6.googleusercontent.com/-0gnNrVjwa0Y/T3R4peGYJwI/AAAAAAAAAGU/uX_9wvRPM9I/s1024/sample_image_12.jpg",
"https://lh3.googleusercontent.com/-HBxuzALS_Zs/T3R4qERykaI/AAAAAAAAAGQ/_qQ16FaZ1q0/s1024/sample_image_13.jpg",
"https://lh4.googleusercontent.com/-cKojDrARNjQ/T3R4qfWSGPI/AAAAAAAAAGY/MR5dnbNaPyY/s1024/sample_image_14.jpg",
"https://lh3.googleusercontent.com/-WujkdYfcyZ8/T3R4qrIMGUI/AAAAAAAAAGk/277LIdgvnjg/s1024/sample_image_15.jpg",
"https://lh6.googleusercontent.com/-FMHR7Vy3PgI/T3R4rOXlEKI/AAAAAAAAAGs/VeXrDNDBkaw/s1024/sample_image_16.jpg",
"https://lh4.googleusercontent.com/-mrR0AJyNTH0/T3R4rZs6CuI/AAAAAAAAAG0/UE1wQqCOqLA/s1024/sample_image_17.jpg",
"https://lh6.googleusercontent.com/-z77w0eh3cow/T3R4rnLn05I/AAAAAAAAAG4/BaerfWoNucU/s1024/sample_image_18.jpg",
"https://lh5.googleusercontent.com/-aWVwh1OU5Bk/T3R4sAWw0yI/AAAAAAAAAHE/4_KAvJttFwA/s1024/sample_image_19.jpg",
"https://lh6.googleusercontent.com/-q-js52DMnWQ/T3R4tZhY2sI/AAAAAAAAAHM/A8kjp2Ivdqg/s1024/sample_image_20.jpg",
"https://lh5.googleusercontent.com/-_jIzvvzXKn4/T3R4t7xpdVI/AAAAAAAAAHU/7QC6eZ10jgs/s1024/sample_image_21.jpg",
"https://lh3.googleusercontent.com/-lnGi4IMLpwU/T3R4uCMa7vI/AAAAAAAAAHc/1zgzzz6qTpk/s1024/sample_image_22.jpg",
"https://lh5.googleusercontent.com/-fFCzKjFPsPc/T3R4u0SZPFI/AAAAAAAAAHk/sbgjzrktOK0/s1024/sample_image_23.jpg",
"https://lh4.googleusercontent.com/-8TqoW5gBE_Y/T3R4vBS3NPI/AAAAAAAAAHs/EZYvpNsaNXk/s1024/sample_image_24.jpg",
"https://lh6.googleusercontent.com/-gc4eQ3ySdzs/T3R4vafoA7I/AAAAAAAAAH4/yKii5P6tqDE/s1024/sample_image_25.jpg",
"https://lh5.googleusercontent.com/--NYOPCylU7Q/T3R4vjAiWkI/AAAAAAAAAH8/IPNx5q3ptRA/s1024/sample_image_26.jpg",
"https://lh6.googleusercontent.com/-9IJM8so4vCI/T3R4vwJO2yI/AAAAAAAAAIE/ljlr-cwuqZM/s1024/sample_image_27.jpg",
"https://lh4.googleusercontent.com/-KW6QwOHfhBs/T3R4w0RsQiI/AAAAAAAAAIM/uEFLVgHPFCk/s1024/sample_image_28.jpg",
"https://lh4.googleusercontent.com/-z2557Ec1ctY/T3R4x3QA2hI/AAAAAAAAAIk/9-GzPL1lTWE/s1024/sample_image_29.jpg",
"https://lh5.googleusercontent.com/-LaKXAn4Kr1c/T3R4yc5b4lI/AAAAAAAAAIY/fMgcOVQfmD0/s1024/sample_image_30.jpg",
"https://lh4.googleusercontent.com/-F9LRToJoQdo/T3R4yrLtyQI/AAAAAAAAAIg/ri9uUCWuRmo/s1024/sample_image_31.jpg",
"https://lh4.googleusercontent.com/-6X-xBwP-QpI/T3R4zGVboII/AAAAAAAAAIs/zYH4PjjngY0/s1024/sample_image_32.jpg",
"https://lh5.googleusercontent.com/-VdLRjbW4LAs/T3R4zXu3gUI/AAAAAAAAAIw/9aFp9t7mCPg/s1024/sample_image_33.jpg",
"https://lh6.googleusercontent.com/-gL6R17_fDJU/T3R4zpIXGjI/AAAAAAAAAI8/Q2Vjx-L9X20/s1024/sample_image_34.jpg",
"https://lh3.googleusercontent.com/-1fGH4YJXEzo/T3R40Y1B7KI/AAAAAAAAAJE/MnTsa77g-nk/s1024/sample_image_35.jpg",
"https://lh4.googleusercontent.com/-Ql0jHSrea-A/T3R403mUfFI/AAAAAAAAAJM/qzI4SkcH9tY/s1024/sample_image_36.jpg",
"https://lh5.googleusercontent.com/-BL5FIBR_tzI/T3R41DA0AKI/AAAAAAAAAJk/GZfeeb-SLM0/s1024/sample_image_37.jpg",
"https://lh4.googleusercontent.com/-wF2Vc9YDutw/T3R41fR2BCI/AAAAAAAAAJc/JdU1sHdMRAk/s1024/sample_image_38.jpg",
"https://lh6.googleusercontent.com/-ZWHiPehwjTI/T3R41zuaKCI/AAAAAAAAAJg/hR3QJ1v3REg/s1024/sample_image_39.jpg",
// Light images
"http://tabletpcssource.com/wp-content/uploads/2011/05/android-logo.png",
"http://simpozia.com/pages/images/stories/windows-icon.png",
"https://si0.twimg.com/profile_images/1135218951/gmail_profile_icon3_normal.png",
"http://www.krify.net/wp-content/uploads/2011/09/Macromedia_Flash_dock_icon.png",
"http://radiotray.sourceforge.net/radio.png",
"http://www.bandwidthblog.com/wp-content/uploads/2011/11/twitter-logo.png",
"http://weloveicons.s3.amazonaws.com/icons/100907_itunes1.png",
"http://weloveicons.s3.amazonaws.com/icons/100929_applications.png",
"http://www.idyllicmusic.com/index_files/get_apple-iphone.png",
"http://www.frenchrevolutionfood.com/wp-content/uploads/2009/04/Twitter-Bird.png",
"http://3.bp.blogspot.com/-ka5MiRGJ_S4/TdD9OoF6bmI/AAAAAAAAE8k/7ydKtptUtSg/s1600/Google_Sky%2BMaps_Android.png",
"http://www.desiredsoft.com/images/icon_webhosting.png",
"http://goodereader.com/apps/wp-content/uploads/downloads/thumbnails/2012/01/hi-256-0-99dda8c730196ab93c67f0659d5b8489abdeb977.png",
"http://1.bp.blogspot.com/-mlaJ4p_3rBU/TdD9OWxN8II/AAAAAAAAE8U/xyynWwr3_4Q/s1600/antivitus_free.png",
"http://cdn3.iconfinder.com/data/icons/transformers/computer.png",
"http://cdn.geekwire.com/wp-content/uploads/2011/04/firefox.png?7794fe",
"https://ssl.gstatic.com/android/market/com.rovio.angrybirdsseasons/hi-256-9-347dae230614238a639d21508ae492302340b2ba",
"http://androidblaze.com/wp-content/uploads/2011/12/tablet-pc-256x256.jpg",
"http://www.theblaze.com/wp-content/uploads/2011/08/Apple.png",
"http://1.bp.blogspot.com/-y-HQwQ4Kuu0/TdD9_iKIY7I/AAAAAAAAE88/3G4xiclDZD0/s1600/Twitter_Android.png",
"http://3.bp.blogspot.com/-nAf4IMJGpc8/TdD9OGNUHHI/AAAAAAAAE8E/VM9yU_lIgZ4/s1600/Adobe%2BReader_Android.png",
"http://cdn.geekwire.com/wp-content/uploads/2011/05/oovoo-android.png?7794fe",
"http://icons.iconarchive.com/icons/kocco/ndroid/128/android-market-2-icon.png",
"http://thecustomizewindows.com/wp-content/uploads/2011/11/Nicest-Android-Live-Wallpapers.png",
"http://c.wrzuta.pl/wm16596/a32f1a47002ab3a949afeb4f",
"http://macprovid.vo.llnwd.net/o43/hub/media/1090/6882/01_headline_Muse.jpg",
// Special cases
"http://cdn.urbanislandz.com/wp-content/uploads/2011/10/MMSposter-large.jpg", // very large image
"file:///sdcard/Universal Image Loader @#&=+-_.,!()~'%20.png", // Image from SD card with encoded symbols
"assets://Living Things @#&=+-_.,!()~'%20.jpg", // Image from assets
"drawable://" + R.drawable.ic_launcher, // Image from drawables
"http://upload.wikimedia.org/wikipedia/ru/b/b6/Как_кот_�_мышами_воевал.png", // Link with UTF-8
"https://www.eff.org/sites/default/files/chrome150_0.jpg", // Image from HTTPS
"http://bit.ly/soBiXr", // Redirect link
"http://img001.us.expono.com/100001/100001-1bc30-2d736f_m.jpg", // EXIF
"", // Empty link
"http://wrong.site.com/corruptedLink"};
public MyAdapter(Context context)
{
this.context=context;
}
@Override
public int getCount()
{
// TODO Auto-generated method stub
return imagesvalues.length;
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent)
{
// TODO Auto-generated method stub
LayoutInflater inflater = (LayoutInflater)context.getSystemService
(Context.LAYOUT_INFLATER_SERVICE);
ImageView imageview;
if(convertView==null)
{
imageview=new ImageView(context);
imageview.setLayoutParams(new GridView.LayoutParams(85, 85));
imageview.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageview.setPadding(8, 8, 8, 8);
}
else
{
imageview = (ImageView)convertView;
}
Bitmap myBitmap = BitmapFactory.decodeFile(imagesvalues[position]);
imageview.setImageBitmap(myBitmap);
return imageview;
}
}