学习内容来自文章：http://www.jcodecraeer.com/a/anzhuokaifa/androidkaifa/2015/0511/2861.html
为了学习，自己又徒手实现了一遍

1.AS中添加 依赖项

  debugImplementation  'com.squareup.leakcanary:leakcanary-android:1.3'
  releaseImplementation 'com.squareup.leakcanary:leakcanary-android-no-op:1.3'

2.创建 Application 子类

public class MyApplication extends Application {
    private RefWatcher mRefWatcher;
    public MyApplication() {
        super();
    }

    @Override
    public void onCreate() {
        super.onCreate();
        mRefWatcher = LeakCanary.install(this);
    }

    @Override
    public void onTerminate() {
        super.onTerminate();
    }
}

3.AndroidManifest.xml文件中添加Application name

<application
        android:name=".MyApplication"
        android:allowBackup="true"
        ......
</application>

4.自定义类并实现单利模式

public class MyClass {
    private static MyClass instance = null;
    private Context context = null;
    private TextView mTextView;

    public static MyClass getInstance(Context context){

        if(instance == null){
            instance = new MyClass(context);
        }
        return  instance;
    }

    private MyClass(Context context){
        this.context = context;
    }

    private MyClass(){
    }

    public void setRetainedTextView(TextView tv){
        this.mTextView = tv;
        mTextView.setText(context.getString(android.R.string.ok));
    }
}

5.实现MainActivity

public class MainActivity extends AppCompatActivity {
    private RefWatcher mRefWatcher;

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

        TextView tv = (TextView) findViewById(R.id.tv_test);
        MyClass.getInstance(this).setRetainedTextView(tv);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
    }
}

运行代码，按返回键会出现程序内存泄露对应的图标

内容简单，入门学习