Question

我正在使用自定义ArrayAdapter来显示我的listView

这是我的代码我想在转到活动时保存我的滚动位置并在恢复时恢复。感谢
包ir.ebiroux.love; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.util.List;

import ir.ebiroux.database.DBAdapter;
import ir.ebiroux.database.Dastan;
import ir.ebiroux.love.R;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.annotation.SuppressLint;
import android.app.ListActivity;
import android.content.Intent;

public class MainActivity extends ListActivity {
    DBAdapter db;
    List<Dastan> dastanha;
    ListView lst;

    boolean isAll;

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


        Button btn_all = (Button) findViewById(R.id.main_all);
        Button btn_fav = (Button) findViewById(R.id.main_fav);



        isAll =true;// pish farz "All" hast
        lst = getListView();
        db = new DBAdapter(getBaseContext());
        db.open();
        Log.i(DBAdapter.TAG, "3");
        dastanha = db.getAllContacts();
        Log.i(DBAdapter.TAG, "4");

        if (dastanha.size() == 0) {

            String destPath = "/data/data/" + getPackageName() + "/databases";

            try {
                CopyDB(getBaseContext().getAssets().open("mydb"),
                        new FileOutputStream(destPath + "/dastanha"));
                Log.i(DBAdapter.TAG, "db copy shod");


                dastanha = db.getAllContacts();

                refreshDisplay()

                Log.i(DBAdapter.TAG, dastanha.size() + "= tedad dastanha");


            } catch (FileNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        } else {
            refreshDisplay();
        }



        btn_all.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                dastanha = db.getAllContacts();
                isAll =true;
                refreshDisplay();
            }
        });
        btn_fav.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                dastanha = db.findFAVContacts();
                isAll=false;
                refreshDisplay();
            }
        });





    }

    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        // TODO Auto-generated method stub
        super.onListItemClick(l, v, position, id);

        Dastan dastan = dastanha.get(position);// migim dastani ke rush kelik


        Intent next = new Intent(this, ShowDastan.class);
        next.putExtra("thisdastan", dastan);
        startActivity(next);

    }


    public void CopyDB(InputStream inputStream, OutputStream outputStream)
            throws IOException {
        // ---copy 1K bytes at a time---
        byte[] buffer = new byte[1024];
        int length;
        while ((length = inputStream.read(buffer)) > 0) {
            outputStream.write(buffer, 0, length);
        }
        inputStream.close();
        outputStream.close();
    }

    public void refreshDisplay() {
        Log.i(DBAdapter.TAG, dastanha.size() + "= tedad dastanha");
        // ye log zadim befahmim ki be kiye

        ArrayAdapter<Dastan> adapter = new DastanAdapter(this, dastanha);

        setListAdapter(adapter);
    }

    @Override
    protected void onResume() {
        // TODO Auto-generated method stub
        super.onResume();

        if (isAll) {
            dastanha = db.getAllContacts();
        }else {
            dastanha=db.findFAVContacts();
        }

        refreshDisplay();
    }
}

Answer 1

你应该@Override 2更多方法。一个用于将当前滚动位置更新/保存到“onScroll”变量中。要触发该操作，请将“implements OnScrollListener”添加到ListActivity定义的签名中。然后在onCreate中调用“getListView（）。setOnScrollListener（this）”来注册你的滚动监听器。或者你也可以像点击听众那样做，只是不要忘记注册。

最后，覆盖活动的“onSaveInstanceState（Bundle yourBundle）”方法，并将上次更新的滚动位置保存到包中。

然后，您可以在“onCreate”方法的捆绑包中检索已保存的滚动位置，该捆绑包在您返回此活动时已存在。使用这些位置以编程方式设置ListView的滚动位置。

Ps：抱歉，从SO的Android应用程序中编写任何代码都不是很方便，但谷歌是你丢失片段的朋友。

保存列表视图滚动位置并在返回时恢复该位置

1 个答案: