从活动到RecyclerView适配器访问变量

Question

我是android的新手，我有两个类： Activity类BureauRateListing.java和Adapter类CurrencySelectorAdapter.java 。

所以我想从一个活动类访问此变量（ public String bs; ）到onBindViewHolder()方法中的RecyclerView Adapter类，以下是我的活动类：

        public String bs;
        private Intent i;

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

            raterv = (RecyclerView) findViewById(R.id.raterv_rv);
            i = getIntent();

            bs = i.getStringExtra("buysell");

}

现在，我该如何从onBindViewHolder()方法内的Activity class到Adapter类中访问变量 （ public String bs; ），并将其作为Extra发送给NextActivity。 下面是我的onBindViewHolder()方法，我想在其中访问变量并将其作为Extra发送：

@Override
    public void onBindViewHolder(CurrencyViewHolder holder, int position) {



        final  BureauRateObject br = itemList.get(position);
        holder.bureauname.setText(br.getBureau_name());
        holder.rates.setText(br.getBuysell());

        final String BureauId = br.getBureau_id();
        final String BureauName = br.getBureau_name();
        final String BureauPhone = br.getBureau_phone();
        final String BureauEmail = br.getBureau_email();
        final String  Website = br.getWebsite();
        final String Branches = br.getBranches();
        final String BureauProfile = br.getBureau_profile();
        final String BureauLogo = br.getBureau_logo();
        final String BureauPhoto = br.getBureau_photo();
        final String currency = br.getBuysell();
        final String BuySell = "Buying";
        final String BuySell_two ="Selling";





        holder.root.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

               Intent i = new Intent(CurrencySelectorAdapter.this.context, SingleForexDetails.class);
               // i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                i.putExtra("bureau_id", BureauId);
                i.putExtra("bureau_name",BureauName);
                i.putExtra("bureau_phone",BureauPhone);
                i.putExtra("bureau_email",BureauEmail);
                i.putExtra("website",Website);
                i.putExtra("branches",Branches);
                i.putExtra("bureau_profile",BureauProfile);
                i.putExtra("bureau_logo",BureauLogo);
                i.putExtra("bureau_photo",BureauPhoto);
                i.putExtra("currency",currency);
                i.putExtra("Buying",BuySell);
                i.putExtra("Selling",BuySell_two);
                context.startActivity(i);

            }
        });



    }

Answer 1

尝试这个

BureauRateListing extends Activity{
 public String bs;
        private Intent i;

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

            raterv = (RecyclerView) findViewById(R.id.raterv_rv);
            i = getIntent();

            bs = i.getStringExtra("buysell");
       }

       public string getbs(){
         return bs;
      }
}


CurrencySelectorAdapter extends ...{

    BureauRateListing mBureauRateListing;    // it's Activity

    CurrencySelectorAdapter (Activity activity){
        mBureauRateListing =activity;
    }
    .
    .
    .

    @Override
        public void onBindViewHolder(CurrencyViewHolder holder, int position) {
          String bs = mBureauRateListing.getbs();
          .
          .
          .
    }

Answer 2

在适配器类中传递活动。

使用此语法访问适配器中的bs变量。

BureauRateListing extends Activity{
    public String bs;
    private Intent i;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.rate_recycler_view);
        CurrencySelectorAdapter currencySelectorAdapter=new (BureauRateListing.this);
        raterv = (RecyclerView) findViewById(R.id.raterv_rv);
        i = getIntent();
        bs = i.getStringExtra("buysell");
   }}

CurrencySelectorAdapter extends ...{
Activity mBureauRateListing;    // it's Activity
CurrencySelectorAdapter (Activity activity){
    mBureauRateListing =activity;
}
@Override
    public void onBindViewHolder(CurrencyViewHolder holder, int position) {
      String bsFromActivity = ((BureauRateListing)mBureauRateListing).bs;
}}

Answer 3

最好在BureauRateListing活动本身中启动新活动。 避免使用适配器的startActivity 。 你可以创建一个View.OnClickListener适配器成员，提供适配器同一个setter setOnClickListener 。 从您的活动中，您可以直接设置此侦听器。 adapter.setOnClikListener(this) 。 在activity中实现View.OnClickListener ，然后在onClick启动新活动。

在您的适配器中添加

private View.OnClickListener mCLickListener;

还添加

 public void setOnClickListener(View.OnClickListener listener){
   mCLickListener = listener;
 }

在onBindViewHolder中

holder.root.setOnClickListener(mCLickListener)

使您的BureauRateListingActivity实现View.OnClickListener

然后，在BureauRateListingActivity内部的onClick方法

       Intent i = new Intent(this, SingleForexDetails.class);
           // i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            i.putExtra("bureau_id", BureauId);
            i.putExtra("bureau_name",BureauName);
            i.putExtra("bureau_phone",BureauPhone);
            i.putExtra("bureau_email",BureauEmail);
            i.putExtra("website",Website);
            i.putExtra("branches",Branches);
            i.putExtra("bureau_profile",BureauProfile);
            i.putExtra("bureau_logo",BureauLogo);
            i.putExtra("bureau_photo",BureauPhoto);
            i.putExtra("currency",currency);
            i.putExtra("Buying",BuySell);
            i.putExtra("Selling",BuySell_two);
            startActivity(i);

最后，在BureauRateListingActivity ，在适配器adapter.setOnClikListener(this).设置侦听器adapter.setOnClikListener(this).

Answer 4

在MainActivity.java中

public static String bs;

在RecycleViewAdapter.java中

import static <app path>.MainActivity.bs;

现在可以访问了。

Answer 5

在适配器的构造函数中，获取BureauRateListing.java类的实例并将其存储在成员变量中

BureauRateListing mAct;
public CurrencySelectorAdapter(BureauRateListing act){
    this.mAct = act;

}

现在，您可以从CurrencySelectorAdapter类的任何方法中使用mAct访问BureauRateListing类的公共实例变量 。

例如

@Override
public void onBindViewHolder(CurrencyViewHolder holder, int position) {
String s = mAct.bs;
}