java - 在 RecyclerView 中显示列表

Question

我正在使用 Android Studio 制作我的 Android 应用。

我有这段代码可以输出以控制我的 Android 手机上安装的所有应用程序。

我该如何更改它，以便将列表输出到我的 Android 应用程序上的 RecyclerView 而不是将其输出到控制台？

package com.example.launcher;

import android.app.Activity;
import android.content.pm.PackageInfo;
import android.graphics.drawable.Drawable;
import android.os.Bundle;

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


public class AppInfo extends Activity {

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

    }

    class PInfo {
        private String appname = "";
        private String pname = "";
        private String versionName = "";
        private int versionCode = 0;
        private Drawable icon;
        private void prettyPrint() {
           System.out.println(appname + "t" + pname + "t" + versionName + "t" + versionCode + "t");
        }
    }

    private ArrayList<PInfo> getPackages() {
        ArrayList<PInfo> apps = getInstalledApps(false); /* false = no system packages */
        final int max = apps.size();
        for (int i=0; i<max; i++) {
            apps.get(i).prettyPrint();
        }
        return apps;
    }

    private ArrayList<PInfo> getInstalledApps(boolean getSysPackages) {
        ArrayList<PInfo> res = new ArrayList<PInfo>();
        List<PackageInfo> packs = getPackageManager().getInstalledPackages(0);
        for(int i=0;i<packs.size();i++) {
            PackageInfo p = packs.get(i);
            if ((!getSysPackages) && (p.versionName == null)) {
                continue ;
            }
            PInfo newInfo = new PInfo();
            newInfo.appname = p.applicationInfo.loadLabel(getPackageManager()).toString();
            newInfo.pname = p.packageName;
            newInfo.versionName = p.versionName;
            newInfo.versionCode = p.versionCode;
            newInfo.icon = p.applicationInfo.loadIcon(getPackageManager());
            res.add(newInfo);
        }
        return res;
    }

}

Answer 1

According to the Android Developer Training :

1. 您需要将 RecyclerView 添加到您的 Activity/fragment 布局
2. 创建一个可以传递给 RecyclerView 的自定义适配器
3. 创建您的适配器可用于呈现单个项目的布局

Activity/fragment :

    mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);

    // use this setting to improve performance if you know that changes
    // in content do not change the layout size of the RecyclerView
    mRecyclerView.setHasFixedSize(true);

    // use a linear layout manager
    mLayoutManager = new LinearLayoutManager(this);
    mRecyclerView.setLayoutManager(mLayoutManager);

    // specify an adapter (see also next example)
    mAdapter = new PInfoAdapter(apps);
    mRecyclerView.setAdapter(mAdapter);

适配器:

public class PInfoAdapter extends RecyclerView.Adapter<PInfoAdapter.ViewHolder> {
    private PInfo[] mDataset;

    // Provide a reference to the views for each data item
    // Complex data items may need more than one view per item, and
    // you provide access to all the views for a data item in a view holder
    public static class ViewHolder extends RecyclerView.ViewHolder {
        // each data item is just a string in this case
        public TextView mTextView;
        public ViewHolder(ViewGroup viewGroup) {
            super(v);
            mTextView = viewGroup.findViewById(R.id.app_name);
        }
    }

    // Provide a suitable constructor (depends on the kind of dataset)
    public PInfoAdapter(PInfo[] myDataset) {
        mDataset = myDataset;
    }

    // Create new views (invoked by the layout manager)
    @Override
    public PInfoAdapter.ViewHolder onCreateViewHolder(ViewGroup parent,
                                                   int viewType) {
        // create a new view
        ViewGroup v = (ViewGroup) LayoutInflater.from(parent.getContext())
                               .inflate(R.layout.your_layout, parent, false);
        // set the view's size, margins, paddings and layout parameters
        ...
        ViewHolder vh = new ViewHolder(v);
        return vh;
    }

    // Replace the contents of a view (invoked by the layout manager)
    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        // - get element from your dataset at this position
        // - replace the contents of the view with that element
        holder.mTextView.setText(mDataset[position].getAppName());

    }

    // Return the size of your dataset (invoked by the layout manager)
    @Override
    public int getItemCount() {
        return mDataset.length;
    }
}

请查看上面的链接，如果您需要任何进一步的帮助，请告诉我。