如何從復選框的列表視圖中將變量設置為true / false？

Question

我使用自定義適配器創建了一個列表視圖，該列表允許我在每個項目旁邊都有一個帶有復選框的項目列表。

因此，我想查看列表中相應項目的復選框，查看是否已選中，如果已選中，則將boolean whiskey = false的值設置為true，以此類推。

我很可能在錯誤的類或xml文件中輸入了代碼，我一直試圖將網上找到的東西拼湊在一起。 我是android studio的新手，因此證明非常困難。 我確實有大約一年的Java經驗值。 我所有的代碼都寫在Eclipse上的工作程序中，我只是費了點時間弄清楚如何將其實現到工作的應用程序中。

提前致謝。

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>

Answer 1

我認為您也可以使用BaseAdapter進行此操作，但我建議改用RecyclerView。

我使用了support-v4和recyclerview-v7庫，如下所示：（確保您未在​​開發AndroidX-檢查整個項目的gradle.properties。它非常相似，但是使用其他庫。）

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，您可能需要對xml進行更多設計。 現在看起來非常基礎。

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>

在主類中，我們為自定義onItemAction函數實現了一個回調偵聽器。 我們通過adapter.setActionListener(this);傳遞偵聽器adapter.setActionListener(this); 並將適配器添加到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，我刪除了BaseAdapter並將其替換為RecyclerView。 我們必須實現一個自定義ViewHolder類，該類包含RecyclerViewList中的每一行。 在ViewHolder中，只要發生復選框更改事件，我們就可以在偵聽器上調用該方法。

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);
    }
}

隨意使用您喜歡的代碼。

有關RecyclerView的更多信息，請參閱Google文檔： https : //developer.android.com/guide/topics/ui/layout/recyclerview