Question

我设计了一个应用程序，然后单击图像视图并在新活动中显示图像，如果后面的app强制关闭。如果需要新的活动代码，我会添加列表视图代码和数据库代码。列表视图代码：

import android.app.ListActivity;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.graphics.Typeface;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;

public class sharedlist extends ListActivity{

    private String[] items;
    private database db;

    private Typeface nazanin;
    private Typeface homa;

    private SharedPreferences sp;

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

        db=new database(this);
        db.open();

        items=new String[db.count("content")];

        nazanin=Typeface.createFromAsset(getAssets(), "Font/nazanin.ttf");
        homa=Typeface.createFromAsset(getAssets(), "Font/homa.ttf");
        sp=getApplicationContext().getSharedPreferences("setting", 0);

        setListAdapter(new AAD());



    }









    class AAD extends ArrayAdapter{

        public AAD() {
            super(sharedlist.this,R.layout.row,items);
        }


        @Override
        public View getView(int position, View convertView, ViewGroup parent) {


            LayoutInflater in=getLayoutInflater();
            View row=in.inflate(R.layout.row,parent,false);
            final String li=db.Display_shared(position,0);
            TextView username=(TextView) row.findViewById(R.id.row_username);
            TextView maintext=(TextView) row.findViewById(R.id.row_maintext);

            username.setText(db.Display_shared(position, 1).toString());
            maintext.setText(db.Display_shared(position, 2).toString());
            ImageView image=(ImageView) row.findViewById(R.id.row_image);
            image.setOnClickListener(new OnClickListener() {

                @Override
                public void onClick(View arg0) {
                    // TODO Auto-generated method stub
                //new imageview("link",li).execute();

                Intent ed=new Intent(sharedlist.this,showImage.class);
                //new imageview("link",li).execute();
                ed.putExtra("postid",li);
                startActivity(ed);
                }
            });

            if(sp.getString("font", "homa").equals("nazanin")){


                maintext.setTypeface(nazanin);


            }else if(sp.getString("font", "homa").equals("homa")){

                maintext.setTypeface(homa);

            }


            if(sp.getString("size", "k").equals("k")){

                maintext.setTextSize(18);

            }else if(sp.getString("size", "k").equals("b")){

                maintext.setTextSize(25);

            }






            return (row);


        }






    }


    @Override
    protected void onPause() {
        super.onPause();
        db.close();
    }
}

和数据库：

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
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.SQLiteOpenHelper;
import android.widget.Toast;



public class database extends SQLiteOpenHelper {


    public final String path="data/data/packagename/databases/";
    public final String Name="database";
    public SQLiteDatabase mydb;

    private final Context mycontext;

    public database(Context context) {
        super(context, "database", null, 1);
        mycontext=context;

    }

    @Override
    public void onCreate(SQLiteDatabase arg0) {

    }

    @Override
    public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {

    }


    public void useable(){

        boolean checkdb=checkdb();

        if(checkdb){

        }else{

            this.getReadableDatabase();

            try{
            copydatabase();
            }catch(IOException e){


            }

        }



    }

    public void open(){

        mydb=SQLiteDatabase.openDatabase(path+Name, null, SQLiteDatabase.OPEN_READWRITE);

    }

    public void close(){
        mydb.close();
    }

    public boolean checkdb(){

        SQLiteDatabase db=null;
        try{    
        db=SQLiteDatabase.openDatabase(path+Name, null, SQLiteDatabase.OPEN_READONLY);
        }
        catch(SQLException e)
        {

        }
        return db !=null ? true:false ;

    }

    public void copydatabase() throws IOException{
        OutputStream myOutput = new FileOutputStream(path+Name);
        byte[] buffer = new byte[1024];
        int length;
        InputStream myInput = mycontext.getAssets().open(Name);
        while ((length = myInput.read(buffer)) > 0) {
        myOutput.write(buffer, 0, length);
        }
        myInput.close();
        myOutput.flush();
        myOutput.close();
    }



    public String Display(int row,int fild){
        Cursor cu= mydb.query("content", null, null, null, null, null, null);
        cu.moveToPosition(row);
        String name=cu.getString(fild);
        return name;
    }

    public Integer count(String table){
        Cursor cu= mydb.query(table, null, null, null, null, null, null);
        int s=cu.getCount();
        return s;
    }

    public void insert(String id,String user,String matn){

        ContentValues cv=new ContentValues();
        cv.put("ID", id);
        cv.put("username", user);
        cv.put("matn", matn);
        mydb.insert("content", "ID", cv);


    }


    public String Display_shared(int row,int fild){
        Cursor cu= mydb.rawQuery("select * from content order by ID DESC",null);
        cu.moveToPosition(row);
        String name=cu.getString(fild);
        return name;
    }


}

日志聊天：

java.lang.IllegalStateException: attempt to re-open an already-closed object: SQLiteDatabase: data/data/package name/databases/database

http://i.stack.imgur.com/iQOUp.png

Answer 1

下面：

final String li = db.Display_shared（position，0）;

行导致问题，因为在设置适用于ListView的适配器之前在open方法中调用了数据库onCreate方法，并且在open方法中再次调用getView方法而没有关闭先前打开的连接在onCreate方法。

如果您是根据位置从数据库获取数据，则使用getView方法而不是onCreate方法打开/关闭连接

或者你也可以使用一个查询从表中获取所有数据并存储在任何数据容器中，如ArrayList, Map,...，而不是多次查询数据库。

java.lang.IllegalStateException：尝试重新打开已关闭的对象：SQLiteDatabase

1 个答案: