java - 为什么我的视图在重新加载时会改变颜色？

Question

我正在开发一个 android 应用程序，并且需要为其使用 recyclerview。我希望它的背景是白色的，但由于某种原因，当我运行应用程序时，它变成了灰色。话虽如此，如果我重新加载活动，或者返回然后再次进入活动，颜色确实会变成白色。有没有人遇到过这样的问题？

这是您首次进入应用程序时的外观

如果您重新加载活动，就会发生这种情况。

这是我的项目

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/trip"
    android:layout_width="match_parent"
    android:layout_height="70dp"
    android:background="@null"
    android:gravity="center"
    android:orientation="horizontal">

    <TextView
        android:id="@+id/destination"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight=".333"
        android:gravity="center"
        android:textSize="24sp" />


    <TextView
        android:id="@+id/start_date"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight=".33"
        android:gravity="center"
        android:textSize="16sp"
        app:layout_constraintStart_toEndOf="@+id/destination" />


    <TextView
        android:id="@+id/trip_length"
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight=".333"
        android:gravity="center" />

</LinearLayout>

这是我的主要活动

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".MainActivity">

    <ImageView
        android:id="@+id/imageView3"
        android:layout_width="180dp"
        android:layout_height="180dp"
        android:contentDescription="@string/app_logo"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.0"
        app:srcCompat="@drawable/app_logo" />

    <TextView
        android:id="@+id/main_name"
        android:layout_width="359dp"
        android:layout_height="26dp"
        android:text="@string/welcome_message"
        android:textSize="18sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.865"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.178" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/trips"
        android:layout_width="350dp"
        android:layout_height="wrap_content"
        android:layout_marginBottom="80dp"
        android:fadingEdge="horizontal|vertical"
        android:maxHeight="200dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.491"
        app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

这是我的适配器

package com.alonkh2.finalproject;

import android.annotation.SuppressLint;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.ArrayList;
import java.util.List;

public class TripAdapter extends RecyclerView.Adapter<TripAdapter.ViewHolder> {
    private ArrayList<Trip> trips;


    public class ViewHolder extends RecyclerView.ViewHolder {
        // Your holder should contain a member variable
        // for any view that will be set as you render a row
        public TextView destination, startDate, endDate, length;

        // We also create a constructor that accepts the entire item row
        // and does the view lookups to find each subview
        public ViewHolder(View itemView) {
            // Stores the itemView in a public final member variable that can be used
            // to access the context from any ViewHolder instance.
            super(itemView);
            destination = (TextView) itemView.findViewById(R.id.destination);
            startDate = (TextView) itemView.findViewById(R.id.start_date);
            // endDate = (TextView) itemView.findViewById(R.id.end_date);
            length = (TextView) itemView.findViewById(R.id.trip_length);

        }
    }

    public TripAdapter(ArrayList<Trip> trips) {
        this.trips = trips;
    }

    @NonNull
    @Override
    public TripAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        Context context = parent.getContext();
        LayoutInflater inflater = LayoutInflater.from(context);

        // Inflate the custom layout
        View contactView = inflater.inflate(R.layout.activity_listview, parent, false);

        // Return a new holder instance
        return new ViewHolder(contactView);
    }

    @SuppressLint("SetTextI18n")
    @Override
    public void onBindViewHolder(@NonNull TripAdapter.ViewHolder holder, int position) {
        Trip trip = trips.get(position);

        // Set item views based on your views and data model
        TextView textView = holder.destination;
        textView.setText(trip.getDestination());
        textView = holder.startDate;
        textView.setText(trip.getStrStartDate().substring(0, trip.getStrStartDate().indexOf(" ")));
//        textView = holder.endDate;
//        textView.setText(trip.getStrEndDate().substring(0, trip.getStrEndDate().indexOf(" ")));
        textView = holder.length;
        textView.setText(trip.getLength() + (trip.getLength() == 1 ? " day" : " days"));
    }

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

标签： javaandroidxml

Answer 1

将此代码放在下面以替换您的 TripAdapter 代码。

package com.alonkh2.finalproject;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.ArrayList;
import java.util.List;

public class TripAdapter extends RecyclerView.Adapter<TripAdapter.ViewHolder> {
    Context context;
    private ArrayList<Trip> trips;


    public class ViewHolder extends RecyclerView.ViewHolder {
        // Your holder should contain a member variable
        // for any view that will be set as you render a row
        public TextView destination, startDate, endDate, length;

        // We also create a constructor that accepts the entire item row
        // and does the view lookups to find each subview
        public ViewHolder(View itemView) {
            // Stores the itemView in a public final member variable that can be used
            // to access the context from any ViewHolder instance.
            super(itemView);
            destination = (TextView) itemView.findViewById(R.id.destination);
            startDate = (TextView) itemView.findViewById(R.id.start_date);
            // endDate = (TextView) itemView.findViewById(R.id.end_date);
            length = (TextView) itemView.findViewById(R.id.trip_length);

        }
    }

    public TripAdapter(Context context, ArrayList<Trip> trips) {
        this.context = context;
        this.trips = trips;
    }

    @NonNull
    @Override
    public TripAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(context);

        // Inflate the custom layout
        View contactView = inflater.inflate(R.layout.activity_listview, parent, false);

        // Return a new holder instance
        return new ViewHolder(contactView);
    }

    @Override
    public void onBindViewHolder(@NonNull TripAdapter.ViewHolder holder, int position) {
        Trip trip = trips.get(position);

        // Set item views based on your views and data model
        holder.destination.setText(trip.getDestination());
        holder.startDate.setText(trip.getStrStartDate().substring(0, trip.getStrStartDate().indexOf(" ")));
//        holder.endDate.setText(trip.getStrEndDate().substring(0, trip.getStrEndDate().indexOf(" ")));
        holder.length.setText(trip.getLength() + (trip.getLength() == 1 ? " day" : " days"));
    }

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