MainActivity.java

package com.mcxtzhang.viewpagerdemo;

import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ImageView;

import com.bumptech.glide.Glide;
import com.mcxtzhang.viewpagerdemo.optimise.ImageTestActivity;

public class MainActivity extends AppCompatActivity {
    ViewPager viewPager;
    ImageView imageView;

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

        findViewById(R.id.click).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                startActivity(new Intent(MainActivity.this, DetailActivity.class));
                overridePendingTransition(R.anim.fade_in, 0);
            }
        });
        viewPager = (ViewPager) findViewById(R.id.viewPager);
        viewPager.setOffscreenPageLimit(1);
        viewPager.setAdapter(new FragmentPagerAdapter(getSupportFragmentManager()) {
            @Override
            public Fragment getItem(int position) {
                return null;
            }

            @Override
            public int getCount() {
                return 0;
            }
        });

        imageView = (ImageView) findViewById(R.id.image);

        findViewById(R.id.click).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                imageView.setImageResource(R.drawable.fan_);
            }
        });

        findViewById(R.id.click).setOnLongClickListener(new View.OnLongClickListener() {
            @Override
            public boolean onLongClick(View v) {
                imageView.setImageDrawable(null);
                return true;
            }
        });
        findViewById(R.id.click).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                startActivity(new Intent(MainActivity.this, ImageTestActivity.class));
                //startActivity(new Intent(MainActivity.this, LoadImgFromNetActivity.class));
            }
        });


        findViewById(R.id.clear).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Glide.get(MainActivity.this).clearMemory();
            }
        });

    }
}