如何在网格视图中显示选定的已安装应用程序

Question

**我有这段代码来显示 Android 中已安装的应用程序。我还想在网格视图中显示用户选择的应用程序。我如何在这段代码中做到这一点？

网格视图是否总是需要适配器？**

这是我的第一个activity:

package com.abhi.test;

import java.util.ArrayList;

import com.example.applist.R;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class Startup extends Activity {

    Button bIns, bSel;

    ArrayList<String> myList = new ArrayList<String>();

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

        bIns = (Button) findViewById(R.id.bList);
        bSel = (Button) findViewById(R.id.bGrid);

    }

    public void viewList(View view) {
        Intent intent = new Intent(getApplicationContext(), MainActivity.class);
        startActivity(intent);
    }

    public void viewGrid(View view) {

        myList = (ArrayList<String>) getIntent().getSerializableExtra("mySelectedList");
        Intent intent = new Intent(getApplicationContext(), Last.class);
        intent.putExtra("mySelectedList",myList);
        startActivity(intent);
    }

}

这是我的第二个activity:

package com.abhi.test;

import java.util.ArrayList;

import com.abhi.test.ApplicationAdapter;

import java.util.List;

import com.example.applist.R;

import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.ActivityNotFoundException;
import android.content.Context;
import android.content.Intent;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageManager;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends ListActivity {
    private PackageManager packageManager = null;
    private List<ApplicationInfo> applist = null;
    private ApplicationAdapter listadaptor = null;
    Button button;
    Bundle bundle;
    CheckBox checkbox;
    ArrayList<ApplicationInfo> selectedapplication = null;

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

        packageManager = getPackageManager();

        button = (Button) findViewById(R.id.button);
        checkbox = (CheckBox) findViewById(R.id.cb_app);

        new LoadApplications().execute();

        //Intent intent = new Intent(this,Last.class);

    }

    public void selectedApps(View view) {

        //new ApplicationAdapter().selApps();
        selectedapplication = ApplicationAdapter.finalList;
        Intent intent = new Intent(MainActivity.this, Startup.class);
        intent.putExtra("mySelectedList",selectedapplication);
        startActivity(intent);


    }

    @Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        super.onListItemClick(l, v, position, id);

        ApplicationInfo app = applist.get(position);
        try {
            Intent intent = packageManager
                    .getLaunchIntentForPackage(app.packageName);

            if (null != intent) {
                startActivity(intent);
            }
        } catch (ActivityNotFoundException e) {
            Toast.makeText(MainActivity.this, e.getMessage(), Toast.LENGTH_LONG)
                    .show();
        } catch (Exception e) {
            Toast.makeText(MainActivity.this, e.getMessage(), Toast.LENGTH_LONG)
                    .show();
        }
    }

    private List<ApplicationInfo> checkForLaunchIntent(
            List<ApplicationInfo> list) {
        ArrayList<ApplicationInfo> applist = new ArrayList<ApplicationInfo>();
        for (ApplicationInfo info : list) {
            try {
                if (packageManager.getLaunchIntentForPackage(info.packageName) != null) 
                {
                    applist.add(info);
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

        return applist;
    }

    private class LoadApplications extends AsyncTask<Void, Void, Void> {
        private ProgressDialog progress = null;

        @Override
        protected Void doInBackground(Void... params) {
            applist = checkForLaunchIntent(packageManager
                    .getInstalledApplications(PackageManager.GET_META_DATA));
            listadaptor = new ApplicationAdapter(MainActivity.this,
                    R.layout.row, applist);

            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            setListAdapter(listadaptor);
            progress.dismiss();
            super.onPostExecute(result);
        }

        @Override
        protected void onPreExecute() {
            progress = ProgressDialog.show(MainActivity.this, null,
                    "Loading application info...");
            super.onPreExecute();
        }

    }
}

第二个数组适配器 activity:

package com.abhi.test;

import java.util.ArrayList;
import java.util.List;

import com.example.applist.R;

import android.content.Context;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

public class ApplicationAdapter extends ArrayAdapter<ApplicationInfo> {
    private List<ApplicationInfo> appsList = null;
    private Context context;
    int position1;
    CheckBox checkBox;
    private PackageManager packageManager;
    public ArrayList<Boolean> checkList = new ArrayList<Boolean>();
    private OnCheckedChangeListener listener;


    public static ArrayList<ApplicationInfo> finalList = null;

    public ApplicationAdapter(Context context, int textViewResourceId,
            List<ApplicationInfo> appsList) {
        super(context, textViewResourceId, appsList);

        this.context = context;
        this.appsList = appsList;
        packageManager = context.getPackageManager();

         for (int i = 0; i < appsList.size(); i++) 
         {
             checkList.add(false);
         }
    }

    @Override
    public int getCount() {
        if (appsList != null) {
            return appsList.size();
        } else {
            return 0;
        }
    }

    @Override
    public ApplicationInfo getItem(int position) {
        if (appsList != null) {
            return appsList.get(position);
        } else {
            return null;
        }
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override //ibuilt function getView()--responsinle for making views
    public View getView(int position, View convertView, ViewGroup parent) {
        View view = convertView;
        if ( view == null) {
            LayoutInflater layoutInflater = (LayoutInflater) context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);         //Understand
            view = layoutInflater.inflate(R.layout.row, null);
        }

        ApplicationInfo data = appsList.get(position);
        if (data != null) {
            TextView appName = (TextView) view.findViewById(R.id.app_name);
            TextView packageName = (TextView) view.findViewById(R.id.app_paackage);
            ImageView iconview = (ImageView) view.findViewById(R.id.app_icon);
            position1=position;
            checkBox = (CheckBox) view.findViewById(R.id.cb_app);       //understand
            checkBox.setTag(Integer.valueOf(position)); // set the tag so we can identify the correct row in the listener
            checkBox.setChecked(checkList.get(position)); // set the status as we stored it        
            checkBox.setOnCheckedChangeListener(mListener); // set the listener


            appName.setText(data.loadLabel(packageManager));
            packageName.setText(data.packageName);
            iconview.setImageDrawable(data.loadIcon(packageManager));


           /* if(checkBox.isChecked())
            {
                finalList.add(data);
                Toast.makeText(getContext(), "App Added", Toast.LENGTH_LONG).show();
            }*/
        }
        return view;
    }

    OnCheckedChangeListener mListener = new OnCheckedChangeListener() {

         public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {   
          checkList.set((Integer)buttonView.getTag(),isChecked);    // get the tag so we know the row and store the status



         }
    };

}

这是最后一个activity，我想在其中显示用户选择的应用程序：

package com.abhi.test;

import java.util.ArrayList;

import com.example.applist.R;

import android.app.Activity;
import android.content.pm.ApplicationInfo;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.GridView;

public class Last extends Activity{

    GridView gridview;
    ArrayList<ApplicationInfo> appList;
    String[] appName = new String[100];
    String[] appPack = new String[100];
    String[] appComp = new String[100];
    ArrayList<String> appInfo = new ArrayList<String>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.last);

        gridview = (GridView) findViewById(R.id.gridview);

        appList = (ArrayList<ApplicationInfo>) getIntent().getSerializableExtra("mylist");

        for(int i=0;i<appList.size();i++)
        {
            appName[i] = appList.get(i).name;
            appPack[i] = appList.get(i).packageName;
            appComp[i] = appName[i]+appPack[i];
            appInfo.add(appComp[i]);
        }



        /* ArrayAdapter<ApplicationInfo> adapter = new ArrayAdapter<ApplicationInfo>(this,
                  android.R.layout.simple_list_item_1, appInfo);

      gridview.setAdapter(adapter);*/
    }
}

XML 为第一个 activity:

<?xml version="1.0" encoding="UTF-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/rootLayout"
    android:layout_width="fill_parent"
    android:layout_height="match_parent"
    android:background="@android:color/white"
    android:orientation="vertical" >

    <Button
        android:id="@+id/bList"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:gravity="fill_horizontal"
        android:onClick="viewList"
        android:text="@string/bInstalledApps" />

     <Button
        android:id="@+id/bGrid"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:gravity="fill_horizontal"
        android:onClick="viewGrid"
        android:text="@string/bSelectedApps" />

</LinearLayout>

XML 第二个 activity:

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

    <Button
        android:id="@+id/button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true" 
        android:onClick="selectedApps"
        android:text="Done"/>

    <ListView
        android:id="@android:id/list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@id/button" />

</RelativeLayout>

row.xml 适配器：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/appdata"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal" >

    <CheckBox
        android:id="@+id/cb_app"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:gravity="center_vertical"
        android:scaleX="1.50"
        android:scaleY="1.50" />

    <ImageView
        android:id="@+id/app_icon"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:padding="3dp"
        android:scaleType="centerCrop" />

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="fill_parent"
        android:gravity="center_vertical"
        android:orientation="vertical"
        android:paddingLeft="5dp" >

        <TextView
            android:id="@+id/app_name"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:gravity="center_vertical"
            android:textStyle="bold" />

        <TextView
            android:id="@+id/app_paackage"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:gravity="center_vertical" />
    </LinearLayout>



</LinearLayout>

XML最后一个activity:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/rootLayout"
    android:layout_width="fill_parent"
    android:layout_height="match_parent"
    android:background="@android:color/white"
    android:orientation="vertical" >

    <GridView
        android:id="@+id/gridview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:columnWidth="90dp"
        android:gravity="center"
        android:horizontalSpacing="10dp"
        android:numColumns="auto_fit"
        android:stretchMode="columnWidth"
        android:verticalSpacing="10dp" />

</LinearLayout>

Answer 1

GridView 是网格中视图的集合。 Android 系统不会神奇地知道你想要在其中显示什么视图。这就是适配器的用武之地。通过为 GridView 设置适配器，您可以告诉 GridView 一些关于您希望它如何显示视图的信息，包括有多少个视图以及每个视图的外观。所以是的，所有 GridView 都需要适配器。

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