Android GridView サンプル

Activityレイアウト

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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="info.typea.kaigiutil.MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal">
        <GridView
            android:id="@+id/grid_menu"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:numColumns="auto_fit"
            android:gravity="center">

        </GridView>
    </LinearLayout>
</android.support.constraint.ConstraintLayout>

Activity

package info.typea.kaigiutil;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.GridView;

public class MainActivity extends AppCompatActivity {

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


        GridView gridView = (GridView)findViewById(R.id.grid_menu);

        gridView.setAdapter(new MenuItemAdapter(this));
    }
}

Adapter

package info.typea.kaigiutil;

import android.content.Context;
import android.media.Image;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;

/**
 * Created by pppiroto on 2017/09/09.
 */
public class MenuItemAdapter extends BaseAdapter{
    private Context context;

    private Integer[] menuItemThumbIds = {
            R.mipmap.ic_launcher,
            R.mipmap.ic_launcher,
            R.mipmap.ic_launcher,
            R.mipmap.ic_launcher,
            R.mipmap.ic_launcher,
            R.mipmap.ic_launcher,
            R.mipmap.ic_launcher
    };

    public MenuItemAdapter(Context context) {
        this.context = context;
    }


    @Override
    public int getCount() {
        return menuItemThumbIds.length;
    }

    @Override
    public Object getItem(int position) {
        return null;
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ImageView imageView;

        if (convertView == null) {
            imageView = new ImageView(this.context);
            imageView.setLayoutParams(new GridView.LayoutParams(85,85));
            imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
            imageView.setPadding(0,0,0,0);
        } else {
            imageView = (ImageView) convertView;
        }
        imageView.setImageResource(menuItemThumbIds[position]);

        return imageView;
    }
}

開発環境や、わかりにくい概念的な部分が体系的に説明されておりわかりやすい良書

ネットで情報を無料で入手できるからこそ、体系的なことを理解していると効率が良いと思う