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我在按钮的单击事件上创建数据库，当我在下一个活动上触发选择查询时，两个相同的记录显示在ListView. 我无法理解发生了什么。

这是我的代码

ListActivity.java

public class ListActivity extends Activity {
    ListView lv;
    ArrayList<String> items = new ArrayList<String>();
    ArrayList<String> items_id = new ArrayList<String>();
    dbhelper dh;
    SQLiteDatabase db;
    int index_id;
    Button btn;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_list);
        Button btn;
        btn = (Button)findViewById(R.id.newProjectlist);
        btn.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {
                // TODO Auto-generated method stub


                    Intent intent= new Intent(ListActivity.this,NewProject.class);
                startActivity(intent);
            }
        });  
        lv = (ListView)findViewById(R.id.projectListView);
        setUpList();
        dh = new dbhelper(this);
        Cursor c = getAllData();
        showAllData(c);  
        registerForContextMenu(lv);      
    }

  @Override
    public void onCreateContextMenu(ContextMenu menu, View v,
            ContextMenuInfo menuInfo) {
        // TODO Auto-generated method stub
        super.onCreateContextMenu(menu, v, menuInfo);

        if(v.getId() == R.id.projectList){
            menu.setHeaderIcon(R.drawable.ic_launcher);
            menu.setHeaderTitle("Record List");
            menu.add(0,1,menu.NONE,"Delete Record");
            menu.add(0,2,menu.NONE,"Show Record");
        }
    }

    @Override
public boolean onContextItemSelected(MenuItem item) {
    // TODO Auto-generated method stub
        int itemId = item.getItemId();
        if(itemId == 1)
        {
            AdapterView.AdapterContextMenuInfo menuinfo = (AdapterContextMenuInfo) item.getMenuInfo();
            int poistion = menuinfo.position;
            String id_string = items_id.get(poistion);
            long id = Long.valueOf(id_string);

            //menuinfo = (AdapterContextMenuInfo) item.getMenuInfo();
            //index_id = menuinfo.position;
            deleteUserData(index_id);
            items_id.remove(poistion);
        }
        if(itemId == 2){
            AdapterView.AdapterContextMenuInfo menuinfo;
            menuinfo = (AdapterContextMenuInfo) item.getMenuInfo();
            index_id = menuinfo.position;
            editUserData(index_id);
        }
    return super.onContextItemSelected(item);
}

    private void editUserData(int indexid) {
        // TODO Auto-generated method stub
        String user_id = items_id.get(indexid);
        Intent intEdit = new Intent(ListActivity.this, MainActivity.class);
        intEdit.putExtra("EditID", user_id);
        startActivityForResult(intEdit, 1);
    }

    private void deleteUserData(int indexid) {
        // TODO Auto-generated method stub
//      String user_id = items_id.get(indexid);
        //Toast.makeText(getApplicationContext(), "id " + user_id, 1).show();
        db = dh.getWritableDatabase();
        db.delete("timer","_ID" + "=" + indexid, null);
        finish();
//      Toast.makeText(getApplicationContext(), "Record deleted successfully", 1).show();
    }

    private void showAllData(Cursor c) {
        // TODO Auto-generated method stub
        while(c.moveToNext())
        {
            int id = c.getInt(0);
            String name = c.getString(1);
            String timerpoint1 = c.getString(2);
            String timerpoint2 = c.getString(3);
            String timerpoint3 = c.getString(4);
            String servicetime1 = c.getString(5);
            String servicetime2 = c.getString(6);
            items.add("" + name);
            items_id.add(""+id);
        }
        setUpList();
    }

    private Cursor getAllData() {
        // TODO Auto-generated method stub
        db = dh.getReadableDatabase();
        //String sortorder = dh.Name + "DESC";
    //  String query ="SELECT DISTINCT name FROM timer";
    //  Cursor c = db.rawQuery(query, null);
    //   if (c != null) {
    //            c.moveToFirst();
    //        }
//      String[] cols = new String[] {dh.Name, "name"};
        Cursor c = db.query(true, "timer",null,null,null,null,null,null, null);   
        //Cursor cur = db.query(Distinct,"timer", null, null, null, null, null, null, null);
        startManagingCursor(c);
        return c;   
        }
    private void setUpList() {
        // TODO Auto-generated method stub
        lv.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,items));
    }   

    }
4

1 回答 1

0

你可以使用这个方法。

public Cursor query (boolean distinct, String table, 
                     String[] columns, String selection, 
                     String[] selectionArgs, String groupBy, 
                     String having, String orderBy, String limit)

将 distinct 变量设置为 true 并按 orderBy 您可以将其替换为您的列名和 ASC，如下所示

KEY_TABLE_COLUMN + " ASC"

 String[] cols = new String[] {"name"};
        Cursor c = db.query(true, "timer",cols,null,null,null,null,null, "name ASC");
于 2013-01-02T09:01:52.430 回答