我在SD卡的app文件夹中存储了一些图像（.jpg）和pdf（.pdf）。列表视图已填充，但当我点击列表视图中的pdf项目时，jpg和pdf的项目都会多次显示在列表视图中。我需要帮助才能搞清楚。谢谢
public class Data_Adapter extends ArrayAdapter<Data_Class>{
Context context;
int ResourceLayoutId;
ArrayList<Data_Class> data=null;
public Data_Adapter(Context c,int r,ArrayList<Data_Class> dc)
{
super(c,r,dc);
this.ResourceLayoutId=r;
this.context=c;
this.data=dc;
}
public View getView(int position, View convertView, ViewGroup parent)
{
View row=convertView;
DataHolder holder=null;
if(row==null)
{
LayoutInflater inflater= ((Activity)context).getLayoutInflater();
row=inflater.inflate(ResourceLayoutId, parent, false);
holder=new DataHolder();
holder.image=(ImageView)row.findViewById(R.id.image1);
holder.txt=(TextView)row.findViewById(R.id.textlist);
row.setTag(holder);
}
else
{
holder=(DataHolder)row.getTag();
}
Data_Class dc=data.get(position);
holder.txt.setText(dc.data);
Bitmap bm = decodeSampledBitmapFromUri(data.get(position).get_path(), 100, 100);
holder.image.setImageBitmap(bm);
return row;
}
public Bitmap decodeSampledBitmapFromUri(String path, int reqWidth, int reqHeight) {
Bitmap bm = null;
// First decode with inJustDecodeBounds=true to check dimensions
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(path, options);
// Calculate inSampleSize
options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
bm = BitmapFactory.decodeFile(path, options);
return bm;
}
public int calculateInSampleSize(
BitmapFactory.Options options, int reqWidth, int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
if (width > height) {
inSampleSize = Math.round((float)height / (float)reqHeight);
} else {
inSampleSize = Math.round((float)width / (float)reqWidth);
}
}
return inSampleSize;
}
public class DataHolder
{
ImageView image;
TextView txt;
}
}
//在主要活动中
private ListView listview1;
private int check_view;
private File targetDirectory;
private File[] files;
protected static ArrayList<Data_Class> dataclass=new ArrayList<Data_Class>();
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
check_view = 0;
super.onCreate(savedInstanceState);
setContentView(R.layout.listview_layout);
listview1=(ListView)findViewById(R.id.List1);
String path = Environment.getExternalStorageDirectory().getAbsolutePath();
String targetPath = path + "/AppName/";
targetDirectory = new File(targetPath);
files = targetDirectory.listFiles();
for(int i=0;i<files.length;i++)
{
dataclass.add(new Data_Class(files[i].getName(),files[i].getAbsolutePath()));
}
Data_Adapter adapter=new Data_Adapter(this,R.layout.img,dataclass);
listview1.setAdapter(adapter);
listview1.setClickable(true);
listview1.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
// TODO Auto-generated method stub
Data_Class mData_Class = (Data_Class)parent.getItemAtPosition(position);
String path = mData_Class.get_path();
if(path.contains(".jpg")){
String path3 = path.substring(path.lastIndexOf("/") + 1);
Intent intent = new Intent();
intent.setAction(Intent.ACTION_VIEW);
intent.setDataAndType(Uri.parse("file://" + Environment.getExternalStorageDirectory().getAbsolutePath()
+ "/AppName/" + path3), "image/*");
startActivity(intent);
//Toast.makeText(ListviewActivity.this, path, Toast.LENGTH_LONG).show();
}
if(path.contains(".pdf")){
String path2 = path.substring(path.lastIndexOf("/") + 1);
File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/AppName/" + path2);
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(Uri.fromFile(file), "application/pdf");
intent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
Intent intent2 = Intent.createChooser(intent, "Open File");
try {
startActivity(intent2);
} catch (ActivityNotFoundException e) {
Toast.makeText(ListviewActivity.this, "No pdf viewer found. Install one. ", Toast.LENGTH_LONG).show();
}
}
}
});
}
}
// Data_Class
public class Data_Class {
public String data;
public String pic;
public Data_Class()
{
super();
}
public Data_Class(String d, String p)
{
super();
this.data=d;
this.pic=p;
}
public String Get_Name()
{
return data;
}
public String get_path()
{
return pic;
}
void Set_Name(String s)
{
data=s;
}
答案 0 :(得分：0)
这样做是因为无论何时单击ListView项，都会调用getView()方法，因此无需再次添加。
yout getView()应该是这样的：
public View getView(int position, View convertView, ViewGroup parent)
{
View row=convertView;
DataHolder holder=null;
if(row==null)
{
LayoutInflater inflater= ((Activity)context).getLayoutInflater();
row=inflater.inflate(ResourceLayoutId, parent, false);
holder=new DataHolder();
holder.image=(ImageView)row.findViewById(R.id.image1);
holder.txt=(TextView)row.findViewById(R.id.textlist);
row.setTag(holder);
Data_Class dc=data.get(position);
holder.txt.setText(dc.data);
Bitmap bm = decodeSampledBitmapFromUri(data.get(position).get_path(), 100, 100);
holder.image.setImageBitmap(bm);
}
else
{
holder=(DataHolder)row.getTag();
}
return row;
}
答案 1 :(得分：0)
我在上面发布的代码中找不到任何问题。
protected static ArrayList<Data_Class> dataclass=new ArrayList<Data_Class>();
正如您已将“dataclass”声明为静态，请确保您不在代码的其他部分修改它。
答案 2 :(得分：0)
问题是列表视图中的先前数据在下次加载listview之前没有被清除。因此，每次活动加载时，我都会清除listview，如下所示。希望将来帮助某人。
adapter.clear();
adapter.notifyDataSetChanged();