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法律研究如何在Android中获取ListView中所有选中的项？
此示例演示了如何在 Android 中获取 ListView 中所有选中的项。
步骤 1 - 在 Android Studio 中创建一个新项目，转到文件 ⇒ 新建项目，并填写所有必需的详细信息以创建新项目。
步骤 2 - 将以下代码添加到 res/layout/activity_main.xml 中。
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context="MainActivity"> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:gravity="center" android:orientation="horizontal"> <Button android:id="@+id/viewCheckedItem" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Select all" /> </LinearLayout> <ListView android:id="@+id/listView" android:layout_width="match_parent" android:layout_height="0dp" android:layout_marginTop="30dp" android:layout_weight="1"> </ListView> </LinearLayout>
步骤 3 - 创建一个 Java 类（CustomAdapter.java）并添加以下代码 -
import android.annotation.SuppressLint;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.CheckBox;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.Objects;
class CustomAdapter extends BaseAdapter {
private Context context;
private static ArrayList<Model> modelArrayList;
CustomAdapter(Context context, ArrayList<Model> modelArrayList) {
this.context = context;
CustomAdapter.modelArrayList = modelArrayList;
}
@Override
public int getViewTypeCount() {
return getCount();
}
@Override
public int getItemViewType(int position) {
return position;
}
@Override
public int getCount() {
return modelArrayList.size();
}
@Override
public Object getItem(int position) {
return modelArrayList.get(position);
}
@Override
public long getItemId(int position) {
return 0;
}
@SuppressLint("InflateParams")
@Override
public View getView(int position, View convertView, ViewGroup parent) {
final ViewHolder holder;
if (convertView == null) {
holder = new ViewHolder();
LayoutInflater inflater = (LayoutInflater)
context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = Objects.requireNonNull(inflater).inflate(R.layout.listitem, null, true);
holder.checkBox = convertView.findViewById(R.id.checkBox);
holder.tvPlayer = convertView.findViewById(R.id.playerNameList);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.checkBox.setText("Checkbox " + position);
holder.tvPlayer.setText(modelArrayList.get(position).getPlayer());
holder.checkBox.setChecked(modelArrayList.get(position).getSelected());
holder.checkBox.setTag(R.integer.btnPlusView, convertView);
holder.checkBox.setTag(position);
holder.checkBox.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Integer pos = (Integer) holder.checkBox.getTag();
Toast.makeText(context, "Checkbox " +pos+ "Clicked!",
Toast.LENGTH_SHORT).show();
if (modelArrayList.get(pos).getSelected()) {
modelArrayList.get(pos).setSelected(false);
} else {
modelArrayList.get(pos).setSelected(true);
}
}
});
return convertView;
}
private class ViewHolder {
CheckBox checkBox;
private TextView tvPlayer;
}
}
步骤 4 - 创建一个 Java 类（Model.java）并添加以下代码 -
class Model {
private boolean isSelected;
private String player;
String getPlayer() {
return player;
}
void setPlayer(String player) {
this.player = player;
}
boolean getSelected() {
return isSelected;
}
void setSelected(boolean selected) {
isSelected = selected;
}
}
步骤 5 - 在 res/values/strings.xml 中添加以下代码
<resources> <string name="app_name">Sample</string> <integer name="btnPlusView">1</integer> <integer name="btnPlusPos">2</integer> </resources>
步骤 6 - 为您的 ListView 创建一个布局（listItem.xml）并添加以下代码 -
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="horizontal" android:layout_width="match_parent" android:layout_height="match_parent"> <CheckBox android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/checkBox" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/playerNameList" android:layout_marginStart="20dp" android:textSize="20sp" /> </LinearLayout>
步骤 7 - 将以下代码添加到 src/MainActivity.java 中
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
private ListView listView;
private ArrayList<Model> modelArrayList;
private CustomAdapter customAdapter;
Button btnSelect, btnDeselect;
public static String[] playerList = new String[]{"Sunil Chetri - INDIA",
"Cristiano Ronaldo - Portugal",
"Lionel Messi - Argentina",
"Neymar Jr - Brazil",
"Eden Hazard - Belgium",
"Gigi Buffon - Italy",
"James Rodrigues - Columbia",
"Sadio Mane - Senegal",
"Toni Kroos - Germany"};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = findViewById(R.id.listView);
btnSelect = findViewById(R.id.viewCheckedItem);
btnDeselect = findViewById(R.id.deSelect);
modelArrayList = getModel(false);
customAdapter = new CustomAdapter(MainActivity.this, modelArrayList);
listView.setAdapter(customAdapter);
btnSelect.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
modelArrayList = getModel(true);
customAdapter = new CustomAdapter(MainActivity.this, modelArrayList);
listView.setAdapter(customAdapter);
Toast.makeText(getApplicationContext(), "Checked all items",
Toast.LENGTH_SHORT).show();
}
});
btnDeselect.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
modelArrayList = getModel(false);
customAdapter = new CustomAdapter(MainActivity.this,modelArrayList);
listView.setAdapter(customAdapter);
Toast.makeText(getApplicationContext(), "Unchecked all items",
Toast.LENGTH_SHORT).show();
}
});
}
private ArrayList<Model> getModel(boolean isSelect) {
ArrayList<Model>list = new ArrayList<>();
for (int i = 0; i < 9; i++) {
Model model = new Model();
model.setSelected(isSelect);
model.setPlayer(playerList[i]);
list.add(model);
}
return list;
}
}步骤 8 - 将以下代码添加到 androidManifest.xml 中
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="app.com.sample"> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round" android:supportsRtl="true" android:theme="@style/AppTheme"> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>
让我们尝试运行您的应用程序。我假设您已将您的实际 Android 移动设备连接到您的电脑。要从 Android Studio 运行应用程序，请打开您项目中的一个 activity 文件，然后单击工具栏中的运行
图标。选择您的移动设备作为选项，然后检查您的移动设备，它将显示您的默认屏幕 -
更新于：2020年7月7日
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