Question

我只是将我的listview设置为空..但现在将数据从另一个活动添加到数据库后，并尝试在列表视图中显示该数据，它给出了相同的emptyview ..它没有显示数据，如何检索数据在listview .. ??

Campaign.java

package com.example.smscampaign;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;



public class Campaign_Details extends Activity  {

    private Demo selectedAdapter;
    private ArrayList<String> list;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_list_demostration);
        TextView text1=(TextView) findViewById(R.id.text1);
        TextView text2=(TextView) findViewById(R.id.text1);
        DataBaseHandler info= new DataBaseHandler(this);
        info.open();
        String data=info.getData();
        info.close();
        String[] values= new String[]{ data };      
        //txt.setText(data);
       // Button next=(Button) findViewById(R.id.next);
      //  Map<String, String[]> storage = new HashMap<String, String[]>();
     //   String[] tableItems = storage.get("ContactTable");


       // next.setOnClickListener(this);
    // final ListView listview = (ListView) findViewById(R.id.listview);

         ListView listview = (ListView) findViewById(R.id.listview);
         ListView listview1 = (ListView) findViewById(R.id.listview1);

         listview.setEmptyView(findViewById(R.id.empty));
        // TextView emptyText = (TextView)findViewById(android.R.id.empty);
        // listview .setEmptyView(emptyText);


      final ArrayList<String> list = new ArrayList<String>();
       for (int i = 0; i < values.length; ++i) {
            selectedAdapter = new Demo(this,values);
            selectedAdapter.setNotifyOnChange(true);


            listview.setAdapter(selectedAdapter);
            list.add(values[i]);
       }

        listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {

          @Override
          public void onItemClick(AdapterView<?> parent, final View view,
              int position, long id) {
              Intent n = new Intent(getApplicationContext(), SmsSend.class);
            startActivity(n);

          }
        });
         }






    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // TODO Auto-generated method stub
        getMenuInflater().inflate(R.menu.main2, menu);
        return true;

    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // TODO Auto-generated method stub

        switch (item.getItemId()) {
        case R.id.nextPage:
            Intent i = new Intent(this,SmsSend.class);
            startActivity(i);
            break;

        }
        return super.onOptionsItemSelected(item);
    }
    }

demo.java //自定义适配器

package com.example.smscampaign;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;

public class Demo extends ArrayAdapter{
    private Campaign_Details list1;
        // used to keep selected position in ListView
       private int selectedPos = -1;   // init value for not-selected
        private Context context;
        private String[] values;

        public Demo(Context context, String[] values) {
            super(context, R.layout.list);
            this.context = context;
            this.values = values;
        }



        public void setSelectedPosition(int pos){
        selectedPos = pos;
             // inform the view of this change
             notifyDataSetChanged();
        }
        public int getSelectedPosition(){
             return selectedPos;
        }
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
                 View v = convertView;
                        LayoutInflater vi =   (LayoutInflater)this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                        v = vi.inflate(R.layout.list, null);

                 // get text view
                     TextView label = (TextView)v.findViewById(R.id.data);

                    if (convertView == null) {            
                        v = vi.inflate(R.layout.list, parent, false);
                    }
                    else
                        v = convertView;
                    TextView text1 = (TextView) v.findViewById(R.id.data);
                    text1.setText(values[position]); 
                    return v;
                }
        }

DatabaseHandler.java

package com.example.smscampaign;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;



public class DataBaseHandler{

    public static final String KEY_ROWID="_id";
    public static final String KEY_NAME="person_name";
    public static final String KEY_SCALE="scale_person";

    private static final String DATABASE_NAME="Scaledb";
    private static final String DATABASE_TABLE="peopleTable";
    private static final int DATABASE_VERSION=1;

    private DbHelper ourHepler;
    private final Context ourContext;
    private SQLiteDatabase ourDatabase;
    public class DbHelper extends SQLiteOpenHelper{

        public DbHelper(Context context) {
            super(context,DATABASE_NAME,null,DATABASE_VERSION);
            // TODO Auto-generated constructor stub
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
            // TODO Auto-generated method stub
            db.execSQL( "CREATE TABLE " + DATABASE_TABLE + " (" +
                    KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT,  " +
                    KEY_NAME + " TEXT NOT NULL, " +
                    KEY_SCALE + " TEXT NOT NULL );"
                    );
            }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            // TODO Auto-generated method stub
            db.execSQL("DROP TABLE IF EXISTS" + DATABASE_TABLE);
            onCreate(db);
        }

    }

    public DataBaseHandler(Context c){
        ourContext=c;
    }


    public DataBaseHandler open() throws SQLException{
        ourHepler = new DbHelper(ourContext);
        ourDatabase=  ourHepler.getWritableDatabase();
        return this;
    }
    public void close()
    {
        ourHepler.close();
    }


    public long entryCreate(String name, String scale) {
        // TODO Auto-generated method stub

        ContentValues cv=new ContentValues();
        cv.put(KEY_NAME, name);
        cv.put(KEY_SCALE, scale);
        return ourDatabase.insert(DATABASE_TABLE, null, cv); 

    }


    public String getData() {
        // TODO Auto-generated method stub
        String[] col= new String[]{KEY_ROWID,KEY_NAME,KEY_SCALE};
        Cursor c=  ourDatabase.query(DATABASE_TABLE, col, null, null, null, null, null);
        String run="";
        int iRow=c.getColumnIndex(KEY_ROWID);
        int iName=c.getColumnIndex(KEY_NAME);
        int iScale=c.getColumnIndex(KEY_SCALE);

        for(c.moveToFirst();!c.isAfterLast();c.moveToNext()){
            run=run+c.getString(iRow)+ " " + c.getString(iName) + " " + c.getString(iScale) + "\n";
        }

        return run;
    }


    public String getScale(long l) {
        // TODO Auto-generated method stub
        String[] col= new String[]{KEY_ROWID,KEY_NAME,KEY_SCALE};
        Cursor c= ourDatabase.query(DATABASE_TABLE, col,KEY_ROWID + "-" + l, null, null, null, null);

        if(c != null){
            c.moveToFirst();
            String scale=c.getString(2);
            return scale;
        }
        return null;
    }


    public String getName(long l)  {
        // TODO Auto-generated method stub
        String[] col= new String[]{KEY_ROWID,KEY_NAME,KEY_SCALE};
        Cursor c= ourDatabase.query(DATABASE_TABLE, col,KEY_ROWID + "-" + l, null, null, null, null);

        if(c != null){
            c.moveToFirst();
            String name=c.getString(1);
            return name;

        }
        return null;
    }


    public  void updateEntry(long lt, String mName, String mScale) {
        // TODO Auto-generated method stub
          ContentValues cvUpdate=new ContentValues();   
          cvUpdate.put(KEY_NAME,mName);
          cvUpdate.put(KEY_SCALE,mScale);
          ourDatabase.update(DATABASE_TABLE,  cvUpdate, KEY_ROWID + "-" + lt, null);
    }


    public void deleteEntry(long ltt) throws SQLException{
        // TODO Auto-generated method stub
        ourDatabase.delete(DATABASE_TABLE, KEY_ROWID + "=" + ltt,null);

    }


    public void getWritableDatabase() {
        // TODO Auto-generated method stub

    }


}

activity_list_demonstration.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/text1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Active Campaign"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:textColor="#4AE56B" />

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="240dp"
        android:orientation="vertical" >

        <ListView
            android:id="@+id/listview"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />

        <TextView
            android:id="@+id/empty"
            style="@android:style/TextAppearance.Large"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_gravity="center"
            android:text="Tab on Icon to start a Campaign" >
        </TextView>
    </LinearLayout>

    <TextView
        android:id="@+id/text2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Closed Campaign"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="140dp"
        android:orientation="vertical" >

        <ListView
            android:id="@+id/listview1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />

        <TextView
            android:id="@+id/empty"
            style="@android:style/TextAppearance.Large"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_gravity="center"
            android:text="No Closed Campaign" >
        </TextView>
    </LinearLayout>

</LinearLayout>

list.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/data"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >
    </TextView>


</LinearLayout>

Answer 1

检查String []数据是否为空。

其次，您的数据库返回一个长字符串而不是String数组，并且在ListView中只能获得一行

for(c.moveToFirst();!c.isAfterLast();c.moveToNext()){
        run=run+c.getString(iRow)+ " " + c.getString(iName) + " " + c.getString(iScale) + "\n";
    }

你也只获得最后一行或空行

将其更改为此类

List<String> dataArray = new ArrayList<String>();
     for(c.moveToFirst();!c.isAfterLast();c.moveToNext()){
           dataArray.add(run+c.getString(iRow)+ " " + c.getString(iName) + " " + c.getString(iScale) + "\n");
        }
    return dataArray;

将您的适配器设置为使用List数组;

公共类SampleAdapter扩展了BaseAdapter {

private Context context;
private List<String> dataArray;

public SampleAdapter(Context context,List<String> dataArray){
    this.context = context;
    this.dataArray = dataArray;

}

@Override
public int getCount() {
    // TODO Auto-generated method stub
    return dataArray.size();
}

@Override
public Object getItem(int arg0) {
    // TODO Auto-generated method stub
    return null;
}

@Override
public long getItemId(int arg0) {
    // TODO Auto-generated method stub
    return 0;
}

static class ViewHolder
{
    TextView txt1;      
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder viewHolder;
    if(convertView==null){
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = inflater.inflate(R.layout.grid_row_item_layout,parent, false);
        viewHolder  = new ViewHolder();
        viewHolder.txt1 = (TextView) convertView.findViewById(R.id.textView1);
        convertView.setTag(viewHolder);
    }
    else{
        viewHolder = (ViewHolder) convertView.getTag();
    }

    viewHolder.txt1.setText(dataArray.get(position));


    return convertView;
}

}

MainActivity

public class MainActivity extends Activity {

SampleAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    List<String> array = new ArrayList<String>();
    array.add("data line 1");
    array.add("data line 2");
    array.add("data line 3");
    array.add("data line 4");
    array.add("data line 5");


    adapter = new SampleAdapter(this,array);
    ListView listView  = (ListView) findViewById(R.id.listView1);
    listView.setAdapter(adapter);




}

}

Answer 2

先解决这个问题

final ArrayList<String> list = new ArrayList<String>();
for (int i = 0; i < values.length; ++i) {

    list.add(values[i]);
}
selectedAdapter = new Demo(this,values);
listview.setAdapter(selectedAdapter);

您的适配器也需要此方法

@Override
public int getCount() {
    // TODO Auto-generated method stub
    return values.length();
}

如何在listview中扩充数据库中的数据

2 个答案: