我使用自定义适配器创建了一个 ListView ，它允许我拥有一个项目列表，每个项目旁边都有复选框。
因此，我想查看列表中相应项目的复选框，看看它是否已选中，如果是，则将 boolean 威士忌 = false 的值设置为 true，对于其他 boolean 值，依此类推。
很可能我的代码位于错误的类或 xml 文件中，我一直在尝试将在互联网上找到的内容拼凑在一起。我是 android studio 的新手，所以事实证明它非常困难。不过，我确实有大约一年的 java 经验。我将所有代码都写在 Eclipse 上的一个工作程序中，我只是花了很长时间才弄清楚如何将其实现到一个工作应用程序中。
提前致谢。
customAdapter.java
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.CompoundButton;
import android.widget.TextView;
import java.util.ArrayList;
public class customAdapter extends BaseAdapter {
private ArrayList<String> list = new ArrayList<String>();
private Context context;
public customAdapter(ArrayList<String> list, Context context) {
this.list = list;
this.context = context;
}
@Override
public int getCount() {
return list.size();
}
@Override
public Object getItem(int pos) {
return list.get(pos);
}
public void setChecked(boolean isChecked){
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
View view = convertView;
if (view == null) {
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view = inflater.inflate(R.layout.activity2_listview, null);
}
//Handle TextView and display string from your list
TextView label = (TextView)view.findViewById(R.id.label);
label.setText(list.get(position));
//Handle buttons and add onClickListeners
CheckBox callchkbox = (CheckBox) view.findViewById(R.id.cb);
callchkbox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
//update isChecked value to model class of list at current position
list.get(position).setChecked(isChecked);
}
});
return view;
}
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
Main2Activity.java
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ListView;
import java.util.ArrayList;
import java.util.Arrays;
import android.widget.CheckBox;
public class Main2Activity extends AppCompatActivity {
boolean Whiskey, Bourbon, Rum, Gin, Vodka, Tequila = false;
String [] userIngredients = {"Whiskey", "Bourbon", "Rum", "Gin", "Vodka", "Tequila", "Club Soda", "Lemon-Lime Soda",
"Ginger ale", "Cola", "Still mineral water", "Tonic Water", "Orange Juice", "Cranberry Juice", "Grapefruit Juice",
"Tomato Juice", "Cream or Half and Half", "Milk", "Ginger Beer", "PineApple Juice", "Lemons", "Limes", "Oranges"};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
ListView listView = (ListView) findViewById(R.id.userIngredients);
ArrayList<String> list = new ArrayList<String>(Arrays.asList(userIngredients));
listView.setAdapter(new customAdapter(list, Main2Activity.this));
}
}
activity_main2.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Main2Activity"
android:id="@+id/linearLayout">
<ListView
android:layout_width="419dp"
android:layout_height="558dp"
android:id="@+id/userIngredients"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/textView2"
tools:layout_conversion_absoluteHeight="731dp"
tools:layout_conversion_absoluteWidth="411dp" />
<TextView
android:id="@+id/textView2"
android:layout_width="374dp"
android:layout_height="60dp"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="16dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:text="Check Your Ingredients"
android:textSize="24sp"
app:fontFamily="@font/cinzel"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
activity2_listview.xml
<?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">
<TextView
android:id="@+id/label"
android:layout_width="323dp"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:text="ingredient"
android:textSize="20sp" />
<CheckBox
android:id="@+id/cb"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
最佳答案
我认为您也可以使用 BaseAdapter 来完成此操作，但我建议改用 RecyclerView。
我使用了 support-v4 和 recyclerview-v7 库，如下所示: (确保您不是在开发 AndroidX - 检查整个项目的 gradle.properties。它非常相似，但使用了其他库。)
build.gradle
android {
compileSdkVersion 28
buildToolsVersion '28.0.3'
...
dependencies {
implementation 'com.android.support:appcompat-v7:28.0.0'
implementation 'com.android.support:support-v4:28.0.0'
implementation 'com.android.support:design:28.0.0'
implementation 'com.android.support.constraint:constraint-layout:1.1.3'
implementation 'com.android.support:recyclerview-v7:28.0.0'
...
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.widget.RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/textView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Check Your Ingredients"
android:textAlignment="center" />
<android.support.v7.widget.RecyclerView
android:id="@+id/recycler_chooser"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:scrollbars="vertical"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" >
</android.support.v7.widget.RecyclerView>
</android.widget.RelativeLayout>
在activity2_listview中，您可能需要对xml进行更多设计。现在看起来非常基本。
activity2_listview.xml
<?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="wrap_content">
<TextView
android:id="@+id/listviewtextlabel"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:text="ingredient"
android:textSize="20sp" />
<CheckBox
android:id="@+id/listviewcheckbox"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
在主类中，我们为自定义 onItemAction 函数实现了一个回调监听器。我们使用 adapter.setActionListener(this); 传递监听器，并将适配器添加到 RecyclerViewer。
MainActivity.java
public class MainActivity extends AppCompatActivity implements CustomAdapter.ItemActionListener {
boolean Whiskey, Bourbon, Rum, Gin, Vodka, Tequila = false;
String [] userIngredients = {"Whiskey", "Bourbon", "Rum", "Gin", "Vodka", "Tequila", "Club Soda", "Lemon-Lime Soda",
"Ginger ale", "Cola", "Still mineral water", "Tonic Water", "Orange Juice", "Cranberry Juice", "Grapefruit Juice",
"Tomato Juice", "Cream or Half and Half", "Milk", "Ginger Beer", "PineApple Juice", "Lemons", "Limes", "Oranges"};
CustomAdapter adapter;
RecyclerView.LayoutManager layoutManager;
RecyclerView recyclerListView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
try {
recyclerListView = (RecyclerView) findViewById(R.id.recycler_chooser);
ArrayList<String> list = new ArrayList<>();
list.addAll(Arrays.asList(userIngredients));
// use this setting to improve performance if you know that changes
// in content do not change the layout size of the RecyclerView
recyclerListView.setHasFixedSize(false);
layoutManager = new LinearLayoutManager(this);
recyclerListView.setLayoutManager(layoutManager);
System.out.println("list.size() " + list.size());
adapter = new CustomAdapter(list,MainActivity.this);
adapter.setActionListener(this);
recyclerListView.setAdapter(adapter);
} catch (Exception e){
e.printStackTrace();
}
}
// callback listener for your items
@Override
public void onItemAction(View view, CustomAdapter.CustomActions customAction, int position) {
final String itemName = adapter.getItem(position);
System.out.println(customAction + ": You clicked " + itemName + " on row number " + position);
switch(itemName){
case "Whiskey":
if(customAction== CustomAdapter.CustomActions.CHECK){
Whiskey=true;
}
else{
Whiskey=false;
}
System.out.println("Whiskey set to: " + Whiskey);
break;
case "Bourbon":
if(customAction== CustomAdapter.CustomActions.CHECK){
Bourbon=true;
}
else{
Bourbon=false;
}
System.out.println("Bourbon set to: " + Bourbon);
break;
//case xyz
// and so on
default:
System.out.println("Not programmed yet: " + itemName);
}
}
}
如上所述，我删除了 BaseAdapter 并将其替换为 RecyclerView。我们必须实现一个自定义 ViewHolder 类，其中包含 RecyclerViewList 中的每一行。在 ViewHolder 中，只要发生复选框更改事件，我们就可以在监听器上调用该方法。
CustomAdapter.java
import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.TextView;
import java.util.ArrayList;
public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.CustomViewHolder> {
//------ helper class for the viewholder
enum CustomActions{
CHECK,UNCHECK
}
// Provide a reference to the views for each row
public class CustomViewHolder extends RecyclerView.ViewHolder {
// each data item is just a string in this case
public TextView mTextView;
public CheckBox mCheckBox;
public CustomViewHolder(View v) {
super(v);
// the view element v is the whole linear layout element
CheckBox.OnCheckedChangeListener checkboxListenerForOneEntry = new CheckBox.OnCheckedChangeListener(){
@Override
public void onCheckedChanged(CompoundButton view, boolean isChecked) {
if (mItemActionListener != null) {
if(isChecked){
// this compoundbutton view element will be the checkbox
mItemActionListener.onItemAction(view, CustomActions.CHECK, getAdapterPosition());
}else{
mItemActionListener.onItemAction(view, CustomActions.UNCHECK, getAdapterPosition());
}
}
}
};
mTextView = v.findViewById(R.id.listviewtextlabel);
mCheckBox = v.findViewById(R.id.listviewcheckbox);
mCheckBox.setOnCheckedChangeListener(checkboxListenerForOneEntry);
}
}
//------
private ArrayList<String> list;
private Context context;
private LayoutInflater mInflater;
private ItemActionListener mItemActionListener;
public CustomAdapter(ArrayList<String> list, Context context) {
this.list = list;
this.context = context;
this.mInflater = LayoutInflater.from(this.context);
}
// allows clicks events to be caught
void setActionListener(ItemActionListener itemActionListener) {
this.mItemActionListener = itemActionListener;
}
// parent activity will implement this method to respond to click events
public interface ItemActionListener {
void onItemAction(View view, CustomActions customAction, int position);
}
// Create new views (invoked by the layout manager)
@Override
public CustomViewHolder onCreateViewHolder(ViewGroup parent,
int viewType) {
// create a new view
View v = mInflater.inflate(R.layout.activity2_listview, parent, false);
return new CustomViewHolder(v);
}
// Replace the contents of a view (invoked by the layout manager)
@Override
public void onBindViewHolder(CustomViewHolder holder, int position) {
// - get element from your dataset at this position
// - replace the contents of the view with that element
holder.mTextView.setText(list.get(position));
}
@Override // Return the size of your dataset (invoked by the layout manager)
public int getItemCount() {
return getCount();
}
public int getCount() {
return list.size();
}
public String getItem(int pos) {
return list.get(pos);
}
}
您可以随意使用该代码。
有关 RecyclerView 的更多信息，请参阅 Google 文档:https://developer.android.com/guide/topics/ui/layout/recyclerview
关于java - 如何从复选框 ListView 将变量设置为 true/false？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/57497085/