如何存储活动的状态并检索回"恢复"

Question

我有一个主要活动，其中包含名称列表的列表视图。单击列表项，将驱散第二个活动。在第二个活动上按下后按钮时，我应该在启动第二个活动时以与同一状态的第一个活动回到第一个活动。我可以知道如何实现这一目标..？

请附上一些示例代码。

这是我的示例代码

Countries_List_Activity.java


public class Countries_list_Activity extends Activity 
{
     String[] countries_list = new String[] {
             "India",
             "Pakistan",
             "Sri Lanka",
             "China",
             "Bangladesh",
             "Nepal",
             "Afghanistan",
             "North Korea",
             "South Korea",
             "Japan",
             "Australia",
             "GreenLand",
             "Las vegas",
             "U.K",
             "Canada",
             "Zimbabwe",
             "Netherland",
             "Singapore",
             "Dubai",
             "Burma",
             "Sutherland",
             "Weat Indies",
             "New Zealand",
             "Kenya",
             "Namibia"
     };
     int index = 0;
     ListView list;
     Context context=this;

    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
         list = (ListView) findViewById(R.id.listview);
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1, countries_list);
        list.setAdapter(adapter);

        list.setOnItemClickListener(new OnItemClickListener() 
        {
            public void onItemClick(AdapterView<?> parent, View view,int position, long id) 
            {
                Object tmp = parent.getItemAtPosition(position);
                String name=tmp.toString();
                System.out.println(name);
                Intent myIntent = new Intent();
                //myIntent.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
                myIntent.setClassName("com.mink7.countries","com.mink7.countries.Country_Selected_Activity");
                myIntent.putExtra("name", name);
                startActivity(myIntent);
            }
        });

    }

    protected void onPause()
    {
        super.onPause();
        index = list.getFirstVisiblePosition();
        // Save scroll position
       /* SharedPreferences preferences = context.getSharedPreferences("SCROLL", 0);
        SharedPreferences.Editor editor = preferences.edit();
        int scroll = list.getScrollY();
        editor.putInt("ScrollValue", scroll);
        editor.commit();*/
    }
    @Override
    protected void onResume()
    {
        super.onResume();
        list.setSelectionFromTop(index, 0);
        // Get the scroll position
        /*SharedPreferences preferences = context.getSharedPreferences("SCROLL", 0);
        int scroll = preferences.getInt("ScrollView", 0);
        list.scrollTo(0, scroll);*/
    }
    public boolean onCreateOptionsMenu(Menu menu)
    {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
}

Country_selected_Activity.java

package com.mink7.countries;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class Country_Selected_Activity extends Activity
{
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.selected_country_display);
        TextView tv=(TextView) findViewById(R.id.textView1);
        Button b=(Button) findViewById(R.id.button1);
        Bundle extras = getIntent().getExtras();
        String name =extras.getString("name");
        tv.setText(name);
        b.setOnClickListener(new OnClickListener() 
        {
            public void onClick(View v)
            {
                Intent intent=new Intent();
                intent.setClassName("com.mink7.countries","com.mink7.countries.Countries_list_Activity");
                startActivity(intent);
            }
        });

    }

}

Answer 1

有很多方法可以做到这一点。一个简单的解决方案是

使您的索引静态变量;

  public static int index = 0;

将其添加到

中

onItemClick(AdapterView<?> parent, View view,int position, long id)
 index = position;

Onpuase中的下线

//index = list.getFirstVisiblePosition();

在onResume（）

中执行此操作

 list.setSelection(index);
//list.setSelectionFromTop(index, 0);