GridView

MainActivity.java

package kanta.gridview_image;

import android.app.Activity;

import android.os.Bundle;
import android.widget.GridView;

public class MainActivity extends Activity
{
GridView gridView;
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        gridView=(GridView)findViewById(R.id.gridView);

        ImageAdapter adapter=new ImageAdapter(this);
         gridView.setAdapter(adapter);
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="kanta.gridview_image.MainActivity">


    <GridView
        android:id="@+id/gridView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:columnWidth="90dp"
        android:gravity="center"
        android:horizontalSpacing="10dp"
        android:numColumns="auto_fit"
        android:stretchMode="columnWidth"


        android:verticalSpacing="10dp" />
</LinearLayout>

ImageAdapter.java

package kanta.gridview_image;

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

/**
 * Created by kanta on 30-Apr-16.
 */
public class ImageAdapter extends BaseAdapter
{
    int[] mThumbIds =
            {
                    R.drawable.china,
                    R.drawable.india,
                    R.drawable.japan,
                    R.drawable.united_kingdom,
                    R.drawable.united_states,
                    R.drawable.china,
                    R.drawable.india,
                    R.drawable.japan,
                    R.drawable.united_kingdom,
                    R.drawable.united_states,
                    R.drawable.china,
                    R.drawable.india,
                    R.drawable.japan,
                    R.drawable.united_kingdom,
                    R.drawable.united_states

            };
    Context context;

    public ImageAdapter(MainActivity mainActivity)
    {
        this.context = mainActivity;
    }

    @Override
    public int getCount() {
        return mThumbIds.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(context);
            imageView.setLayoutParams(new GridView.LayoutParams(300, 300));
            imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
            imageView.setPadding(8, 8, 8, 8);

        }
        
        else
        {
            imageView = (ImageView) convertView;
        }
        imageView.setImageResource(mThumbIds[position]);
        return imageView;
    }
}