Android Studio的代码笔记--Adapter+GridView学习

Adapter+GridView学习

Adapter+GridView
- SimpleAdapter+GridView
- - activity_main.xml
  - appicon.xml
  - MainActivity
- 自定义BaseAdapter+GridView+已下载应用PackageInfo
- - AppAdapter
  - MainActivity2
其他
- 获取已下载应用信息函数
- 获取所有应用信息函数
- ImageView产生圆角的方法
- 背景设置很渐变
- 设置选择效果，按压效果，未选择效果

Adapter+GridView

SimpleAdapter+GridView

SimpleAdapter+GridView 简单显示一组图片和名称

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="match_parent"android:background="#91F3F0"><LinearLayoutandroid:layout_width="match_parent"android:layout_height="match_parent"android:layout_marginLeft="30dp"android:layout_marginTop="30dp"android:layout_marginRight="30dp"android:orientation="vertical"><GridViewandroid:id="@+id/gv_app"android:layout_width="match_parent"android:layout_height="match_parent"android:horizontalSpacing="30dp"android:numColumns="6"android:verticalSpacing="30dp" /></LinearLayout>
</LinearLayout>

android:horizontalSpacing="30dp"横向间隔距离
android:numColumns="6"设置一行中有6列
android:verticalSpacing="30dp"纵向间隔距离

效果
在这里插入图片描述

appicon.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:app="http://schemas.android.com/apk/res-auto"android:layout_width="match_parent"android:layout_height="match_parent"android:gravity="center"><LinearLayoutandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:gravity="center"android:orientation="vertical"><LinearLayoutandroid:layout_width="match_parent"android:layout_height="match_parent"android:layout_weight="1"android:gravity="center"android:orientation="vertical"><androidx.cardview.widget.CardViewandroid:layout_width="80dp"android:layout_height="80dp"android:layout_gravity="center"android:layout_marginTop="20dp"android:gravity="center"app:cardCornerRadius="10dp"app:cardElevation="0dp"><ImageViewandroid:id="@+id/iv_icon"android:layout_width="match_parent"android:layout_height="match_parent"android:scaleType="fitCenter" /></androidx.cardview.widget.CardView></LinearLayout><LinearLayoutandroid:layout_width="match_parent"android:layout_height="match_parent"android:layout_weight="1"android:gravity="center"android:orientation="vertical"><TextViewandroid:id="@+id/tv_icon"android:layout_width="wrap_content"android:layout_height="23dp"android:layout_below="@id/iv_icon"android:layout_gravity="center"android:layout_marginTop="20dp"android:layout_marginBottom="20dp"android:gravity="center"android:text="name"android:textColor="@color/white"android:textSize="18sp" /></LinearLayout></LinearLayout>
</LinearLayout>

其中androidx.cardview.widget.CardView使ImageView产生圆角效果

效果

在这里插入图片描述

MainActivity

package com.lxh.dialogtest;import androidx.appcompat.app.AppCompatActivity;import android.content.Context;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.GridView;
import android.widget.SimpleAdapter;
import android.widget.Toast;import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;public class MainActivity extends AppCompatActivity {private static final String TAG = "MainActivity lxh";private Context mContext;private GridView gv_app;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mContext = MainActivity.this;gv_app = (GridView) findViewById(R.id.gv_app);int[] appicons = {R.drawable.ic_launcher_background, R.drawable.ic_launcher_background,R.drawable.ic_launcher_background, R.drawable.ic_launcher_background,R.drawable.ic_launcher_background, R.drawable.ic_launcher_background,R.drawable.ic_launcher_background, R.drawable.ic_launcher_background};String[] appnames = {"图标1", "图标2", "图标3", "图标4", "图标5", "图标6", "图标7", "图标8"};List<Map<String, Object>> listitems = new ArrayList<>();for (int i = 0; i < appnames.length; i++) {Map<String, Object> listitem = new HashMap<>();listitem.put("icon", appicons[i]);listitem.put("name", appnames[i]);listitems.add(listitem);}SimpleAdapter simpleAdapter = new SimpleAdapter(this, listitems, R.layout.appicon, new String[]{"icon", "name"}, new int[]{R.id.iv_icon, R.id.tv_icon});gv_app.setAdapter(simpleAdapter);gv_app.setOnItemClickListener(new AdapterView.OnItemClickListener() {@Overridepublic void onItemClick(AdapterView<?> parent, View view, int position, long id) {Toast.makeText(mContext, "点击了第 " + position + " 项", Toast.LENGTH_SHORT).show();}});}
}

效果如图
在这里插入图片描述

自定义BaseAdapter+GridView+已下载应用PackageInfo

activity_main.xml和appicon.xml不变

AppAdapter

package com.lxh.dialogtest;import android.content.Context;
import android.content.pm.PackageInfo;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;import java.util.List;/*** create by lxh on 2023/12/12 Time：9:42* tip:*/
public class AppAdapter extends BaseAdapter {private List<PackageInfo> appList;Context context;public AppAdapter(List<PackageInfo> appList, Context mcontext) {this.appList = appList;this.context = mcontext;}@Overridepublic int getCount() {return appList.size();}@Overridepublic Object getItem(int position) {return appList.get(position);}@Overridepublic long getItemId(int position) {return position;}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {ViewHolder holder;if (convertView == null) {holder = new ViewHolder();convertView = LayoutInflater.from(context).inflate(R.layout.appicon, null);holder.appIcon = convertView.findViewById(R.id.iv_icon);holder.appName = convertView.findViewById(R.id.tv_icon);convertView.setTag(holder);} else {holder = (ViewHolder) convertView.getTag();}PackageInfo pi = (PackageInfo) getItem(position);holder.appIcon.setImageDrawable(pi.applicationInfo.loadIcon(context.getPackageManager()));holder.appName.setText(pi.applicationInfo.loadLabel(context.getPackageManager()).toString());return convertView;}static class ViewHolder {public ImageView appIcon;public TextView appName;}
}

MainActivity2

package com.lxh.dialogtest;import androidx.appcompat.app.AppCompatActivity;import android.content.Context;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.GridView;
import android.widget.Toast;import java.util.ArrayList;
import java.util.List;public class MainActivity2 extends AppCompatActivity {private static final String TAG = "MainActivity2 lxh";private Context mContext;private GridView gv_app;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);mContext = MainActivity2.this;gv_app = (GridView) findViewById(R.id.gv_app);Appinfo = get_InstallApp(mContext);if (Appinfo != null) {gv_app.setAdapter(new AppAdapter(Appinfo, mContext));gv_app.setOnItemClickListener(new AdapterView.OnItemClickListener() {@Overridepublic void onItemClick(AdapterView<?> parent, View view, int position, long id) {Toast.makeText(mContext, "你点击了~" + position + "~项", Toast.LENGTH_SHORT).show();}});}}List<PackageInfo> Appinfo = null;public List<PackageInfo> get_InstallApp(Context context) {List<PackageInfo> installApp = new ArrayList<>();List<PackageInfo> packageInfos = null;packageInfos = context.getPackageManager().getInstalledPackages(PackageManager.COMPONENT_ENABLED_STATE_DEFAULT);for (PackageInfo packageInfo : packageInfos) {if ((packageInfo.applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) == 0) {installApp.add(packageInfo);}}return installApp;}
}

效果如图
在这里插入图片描述

其他

获取已下载应用信息函数

    public List<PackageInfo> get_InstallApp(Context context) {List<PackageInfo> installApp = new ArrayList<>();List<PackageInfo> packageInfos = null;packageInfos = context.getPackageManager().getInstalledPackages(PackageManager.COMPONENT_ENABLED_STATE_DEFAULT);for (PackageInfo packageInfo : packageInfos) {if ((packageInfo.applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) == 0) {installApp.add(packageInfo);}}return installApp;}

获取所有应用信息函数

    public List<PackageInfo> get_allApp(Context context) {List<PackageInfo> installApp = new ArrayList<>();List<PackageInfo> packageInfos = null;packageInfos = context.getPackageManager().getInstalledPackages(PackageManager.COMPONENT_ENABLED_STATE_DEFAULT);for (PackageInfo packageInfo : packageInfos) {installApp.add(packageInfo);}return installApp;}

ImageView产生圆角的方法

            <androidx.cardview.widget.CardViewandroid:layout_width="80dp"android:layout_height="80dp"android:layout_gravity="center"android:layout_marginTop="20dp"android:gravity="center"app:cardCornerRadius="10dp"app:cardElevation="0dp"><ImageViewandroid:id="@+id/iv_icon"android:layout_width="match_parent"android:layout_height="match_parent"android:scaleType="fitCenter" /></androidx.cardview.widget.CardView>

效果
在这里插入图片描述

背景设置很渐变

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android"><item android:state_focused="false" android:state_pressed="false"><shape><gradient android:angle="270" android:endColor="#9D3DE1" android:startColor="#4379E4" /></shape></item>
</selector>

效果
在这里插入图片描述

设置选择效果，按压效果，未选择效果

            <GridViewandroid:id="@+id/gv_app"android:layout_width="match_parent"android:layout_height="match_parent"android:horizontalSpacing="30dp"android:numColumns="6"android:verticalSpacing="30dp"android:listSelector="@drawable/cg_white"/>

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android"><item android:state_focused="true"><shape><corners android:bottomLeftRadius="10dp" android:bottomRightRadius="10dp" android:topLeftRadius="10dp" android:topRightRadius="10dp" /><stroke android:width="2dp" android:color="@color/white" /></shape></item><item android:state_pressed="true"><shape><corners android:bottomLeftRadius="10dp" android:bottomRightRadius="10dp" android:topLeftRadius="10dp" android:topRightRadius="10dp" /><stroke android:width="2dp" android:color="@color/white" /></shape></item><item android:state_focused="false"><shape><corners android:bottomLeftRadius="10dp" android:bottomRightRadius="10dp" android:topLeftRadius="10dp" android:topRightRadius="10dp" /></shape></item>
</selector>