Editor

ChooserActivity.java

package com.google.samples.quickstart.signin;

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;

/**
 * Simple list-based Activity to redirect to one of the other Activities. The code here is
 * uninteresting, {@link SignInActivity} is a good place to start if you are curious about
 * {@code GoogleSignInApi}.
 */
public class ChooserActivity extends AppCompatActivity implements AdapterView.OnItemClickListener {

private static final Class[] CLASSES = new Class[]{
            SignInActivity.class,
            SignInActivityWithDrive.class,
            IdTokenActivity.class,
            ServerAuthCodeActivity.class,
            RestApiActivity.class,
    };

private static final int[] DESCRIPTION_IDS = new int[] {
            R.string.desc_sign_in_activity,
            R.string.desc_sign_in_activity_scopes,
            R.string.desc_id_token_activity,
            R.string.desc_auth_code_activity,
            R.string.desc_rest_activity,
    };

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

// Set up ListView and Adapter
        ListView listView = findViewById(R.id.list_view);

MyArrayAdapter adapter = new MyArrayAdapter(this, android.R.layout.simple_list_item_2, CLASSES);
        adapter.setDescriptionIds(DESCRIPTION_IDS);

listView.setAdapter(adapter);
        listView.setOnItemClickListener(this);
    }

@Override
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
        Class clicked = CLASSES[position];
        startActivity(new Intent(this, clicked));
    }

public static class MyArrayAdapter extends ArrayAdapter<Class> {

private Context mContext;
        private Class[] mClasses;
        private int[] mDescriptionIds;

public MyArrayAdapter(Context context, int resource, Class[] objects) {
            super(context, resource, objects);

mContext = context;
            mClasses = objects;
        }

@Override
        public View getView(int position, View convertView, ViewGroup parent) {
            View view = convertView;

if (convertView == null) {
                LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(LAYOUT_INFLATER_SERVICE);
                view = inflater.inflate(android.R.layout.simple_list_item_2, null);
            }

((TextView) view.findViewById(android.R.id.text1)).setText(mClasses[position].getSimpleName());
            ((TextView) view.findViewById(android.R.id.text2)).setText(mDescriptionIds[position]);

return view;
        }

public void setDescriptionIds(int[] descriptionIds) {
            mDescriptionIds = descriptionIds;
        }
    }
}