无法解析 'myAdapter' 中的方法 'getContext'

Question

我收到上下文错误。它显示无法在我的适配器 class 中解析 getcontext。我正在创建一个地震报告应用程序，就像 udacity 课程中的应用程序一样。我添加了回收站视图和卡片 view.therefore 我做了一个适配器 class。当我开始向我的幅度文本视图添加颜色时，我创建了一种获取幅度颜色方法的方法，在该方法中我必须从 colors.xml 文件中取出颜色，但它需要上下文并且它说上下文无法解析。我正在提供我的应用程序代码...请帮助我，我是 android 开发的新手

我的适配器class代码：-

包 com.example.earthquakereport;

import android.content.Context;
import android.graphics.drawable.GradientDrawable;
import android.os.Build;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.core.content.ContextCompat;
import androidx.recyclerview.widget.RecyclerView;

import java.text.DecimalFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Date;
import java.util.List;

public class myAdapter extends RecyclerView.Adapter<myAdapter.myViewHolder>{
    ArrayList<DataModel> dataModels;
    private static final String LOCATION_SEPARATOR = " of ";
    String primaryLocation,secondaryLocation;
    public myAdapter(ArrayList<DataModel> dataModels) {
    this.dataModels = dataModels;

}


    @NonNull
    @Override
    public myViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.single_row,parent,false);
        return new myViewHolder(view);
    }

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

//        holder.mag.setText(dataModels.get(position).getMag());
        holder.location.setText(dataModels.get(position).getLocation());
        Date dateObject = new Date(dataModels.get(position).getTimeInMilliseconds());
        String formattedDate = formatDate(dateObject);
        holder.date.setText(formattedDate);
        String formattedTime = formatTime(dateObject);
        holder.time.setText(formattedTime);

        String originalLocation = dataModels.get(position).getLocation();
        if(originalLocation.contains(LOCATION_SEPARATOR)){
            String[] parts = originalLocation.split(LOCATION_SEPARATOR);
            primaryLocation = parts[0];
            secondaryLocation = parts[1];
        }
//        else{
//            primaryLocation = context.getString(R.string.near_the);
//            secondaryLocation = originalLocation;
//        }
        holder.location.setText(primaryLocation);
        holder.location2.setText(secondaryLocation);


        String formattedMagnitude = formatMagnitude(dataModels.get(position).getMag());
        holder.mag.setText(formattedMagnitude);
        GradientDrawable magnitudeCircle = (GradientDrawable) holder.mag.getBackground();

        // Get the appropriate background color based on the current earthquake magnitude
        int magnitudeColor = getMagnitudeColor(dataModels.get(position).getMag());

        // Set the color on the magnitude circle
        magnitudeCircle.setColor(magnitudeColor);



    }

    @Override
    public int getItemCount() {
        return dataModels.size();
    }


    public class myViewHolder extends RecyclerView.ViewHolder {
        TextView mag,location,location2,date,time;


        public myViewHolder(@NonNull View itemView) {
            super(itemView);
            mag = itemView.findViewById(R.id.mag_textview);
            location = itemView.findViewById(R.id.location_textview);
            location2 = itemView.findViewById(R.id.location2_textview);
            date = itemView.findViewById(R.id.date_textview);
            time = itemView.findViewById(R.id.time_textview);


        }
    }
    private String formatDate(Date dateObject) {
        SimpleDateFormat dateFormat = new SimpleDateFormat("LLL dd, yyyy");
        return dateFormat.format(dateObject);
    }

    /**
     * Return the formatted date string (i.e. "4:30 PM") from a Date object.
     */
    private String formatTime(Date dateObject) {
        SimpleDateFormat timeFormat = new SimpleDateFormat("h:mm a");
        return timeFormat.format(dateObject);
    }

    private String formatMagnitude(double magnitude) {
        DecimalFormat magnitudeFormat = new DecimalFormat("0.0");
        return magnitudeFormat.format(magnitude);
    }
    private int getMagnitudeColor(double magnitude) {
        int magnitudeColorResourceId;
        int magnitudeFloor = (int) Math.floor(magnitude);
        switch (magnitudeFloor) {
            case 0:
            case 1:
                magnitudeColorResourceId = R.color.magnitude1;
                break;
            case 2:
                magnitudeColorResourceId = R.color.magnitude2;
                break;
            case 3:
                magnitudeColorResourceId = R.color.magnitude3;
                break;
            case 4:
                magnitudeColorResourceId = R.color.magnitude4;
                break;
            case 5:
                magnitudeColorResourceId = R.color.magnitude5;
                break;
            case 6:
                magnitudeColorResourceId = R.color.magnitude6;
                break;
            case 7:
                magnitudeColorResourceId = R.color.magnitude7;
                break;
            case 8:
                magnitudeColorResourceId = R.color.magnitude8;
                break;
            case 9:
                magnitudeColorResourceId = R.color.magnitude9;
                break;
            default:
                magnitudeColorResourceId = R.color.magnitude10plus;
                break;
        }

        return ContextCompat.getColor(getContext(),magnitudeColorResourceId);
    }





}

in last line "ContextCompat.getColor(getContext(),magnitudeColorResourceId);"...i am getting error of get context .

Answer 1

你不能在适配器 class 中使用 getContext() 而不是你可以从你的 activity 传递上下文，在那里你通过适配器的参数将你的适配器设置为 recyclerview 或者你可以这样做：在 myAdapter class

中声明上下文

Context context;

 @NonNull
    @Override
    public myViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
       // you can get context from this line
        context = parent.getContext();

        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.single_row,parent,false);
        return new myViewHolder(view);
    }

无法解析 'myAdapter' 中的方法 'getContext'

Cannot resolve method 'getContext' in 'myAdapter'

java

android

android-context

android-cardview

android-recyclerview