LayoutInflaterFactory examples

CustomViewsLayoutInflaterFactory.java

package nz.bradcampbell.app.presentation;

import android.content.Context;
import android.support.v4.view.LayoutInflaterFactory;
import android.util.AttributeSet;
import android.view.View;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

/**
 * This layout inflater inflates all custom views in the "nz.bradcampbell.app.presentation.customviews" 
 * package so that you don't need to use fully qualified classnames in the XML layout files.
 */
public class CustomViewsLayoutInflaterFactory implements LayoutInflaterFactory {
    private static final String CUSTOM_VIEWS_PACKAGE = "nz.bradcampbell.app.presentation.customviews.";

    private static final Set<String> namesVisited = new HashSet<>();
    private static final Map<String, Constructor<? extends View>> constructorMap = new HashMap<>();
    private static final Class<?>[] constructorSignature = new Class[] {
            Context.class, AttributeSet.class };
            
    private AppCompatActivity appCompatActivity;

    public CustomViewsLayoutInflaterFactory(AppCompatActivity appCompatActivity) {
        this.appCompatActivity = appCompatActivity;
    }

    @Override
    public View onCreateView(View parent, String name, Context context, AttributeSet attrs) {
        View result = null;
        if (!namesVisited.contains(name)) {
            namesVisited.add(name);
            try {
                // Class not found in the cache, see if it's real, and try to add it
                Class<? extends View> clazz = context.getClassLoader()
                        .loadClass(CUSTOM_VIEWS_PACKAGE + name).asSubclass(View.class);
                constructorMap.put(name, clazz.getConstructor(constructorSignature));
            } catch (ClassNotFoundException e) {
                // This will get picked up by the system later. No need to handle here.
            } catch (NoSuchMethodException e) {
                // This is expected and will happen for any custom view that doesn't have
                // the custom constructor required
            }
        }
        Constructor<? extends View> constructor = constructorMap.get(name);
        if (constructor != null) {
            try {
                constructor.setAccessible(true);
                result = constructor.newInstance(context, attrs);
            } catch (InvocationTargetException e) {
                throw new RuntimeException(e);
            } catch (InstantiationException e) {
                throw new RuntimeException(e);
            } catch (IllegalAccessException e) {
                throw new RuntimeException(e);
            }
        }
        if (result == null) {
            // Try to let the Activity handle it (inflating fragments from XML)
            result = appCompatActivity.onCreateView(name, context, attrs);
        }
        if (result == null) {
            // Get themed views from app compat
            result = appCompatActivity.getDelegate().createView(parent, name, context, attrs);
        }
        return result;
    }
}

MainActivityCloneInContext.java

/**
 * An example of using cloneInContext 
 */
public class MainActivityCloneInContext extends AppCompatActivity {
    private LayoutInflater layoutInflater;

    @Override protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        layoutInflater = getLayoutInflater().cloneInContext(this);
        LayoutInflaterCompat.setFactory(layoutInflater, new CustomViewsLayoutInflaterFactory());
        setContentView(R.layout.activity_main);
    }

    @NonNull @Override public LayoutInflater getLayoutInflater() {
        return layoutInflater;
    }

    @Override public Object getSystemService(@NonNull String name) {
        if (name.equals(LAYOUT_INFLATER_SERVICE)) {
            if (layoutInflater == null) {
                layoutInflater = (LayoutInflater) super.getSystemService(name);
            }
            return layoutInflater;
        }
        return super.getSystemService(name);
    }
}

MainActivityComponentViewFactory.java

package nz.bradcampbell.app.presentation;

import android.content.Context;
import android.support.v4.view.LayoutInflaterFactory;
import android.util.AttributeSet;
import android.view.View;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import static nz.bradcampbell.app.util.Strings.startsWith;

/**
 * This layout inflater will inflate any view with the constructor signature as follows:
 * <init>(Context, AttributeSet, MainActivityComponent)
 */
public class MainActivityComponentViewFactory implements LayoutInflaterFactory {
    private static final String PRESENTATION_PACKAGE = "nz.bradcampbell.app.presentation";

    private static final Set<String> namesVisited = new HashSet<>();
    private static final Map<String, Constructor<? extends View>> constructorMap = new HashMap<>();
    private static final Class<?>[] constructorSignature = new Class[] {
            Context.class, AttributeSet.class, MainActivityComponent.class };

    private MainActivityComponent component;

    public MainActivityComponentViewFactory(MainActivityComponent component) {
        this.component = component;
    }

    @Override
    public View onCreateView(View parent, String name, Context context, AttributeSet attrs) {
        View result = null;
        if (startsWith(name, PRESENTATION_PACKAGE)) {
            if (!namesVisited.contains(name)) {
                namesVisited.add(name);
                try {
                    // Class not found in the cache, see if it's real, and try to add it
                    Class<? extends View> clazz = context.getClassLoader()
                            .loadClass(name).asSubclass(View.class);
                    constructorMap.put(name, clazz.getConstructor(constructorSignature));
                } catch (ClassNotFoundException e) {
                    // This will get picked up by the system later. No need to handle here.
                } catch (NoSuchMethodException e) {
                    // This is expected and will happen for any custom view that doesn't have
                    // the custom constructor required
                }
            }
            Constructor<? extends View> constructor = constructorMap.get(name);
            if (constructor != null) {
                try {
                    constructor.setAccessible(true);
                    result = constructor.newInstance(context, attrs, component);
                } catch (InvocationTargetException e) {
                    throw new RuntimeException(e);
                } catch (InstantiationException e) {
                    throw new RuntimeException(e);
                } catch (IllegalAccessException e) {
                    throw new RuntimeException(e);
                }
            }
        }
        if (result == null) {
            // Try to let the Activity handle it (inflating fragments from XML)
            result = component.getActivity().onCreateView(name, context, attrs);
        }
        if (result == null) {
            // Get themed views from app compat
            result = component.getAppCompatDelegate().createView(parent, name, context, attrs);
        }
        return result;
    }
}

MainActivityNoFactory.java

/**
 * An example of using the Activity as the factory
 */ 
public class MainActivityNoFactory extends AppCompatActivity {
    @Override protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    @Override
    public View onCreateView(View parent, String name, @NonNull Context context, @NonNull AttributeSet attrs) {
        View result = super.onCreateView(parent, name, context, attrs);
        
        // Custom view inflation here
        if (result == null) {
            if (TextUtils.equals(name, "CustomView")) {
                result = new CustomView(context, attrs);
            }
        }
        
        return result;
    }
}

MyLayoutInflaterFactory.java

/**
 * This is just sample code that shows how you can avoid reflection for inflating certain views, 
 * perhaps in performance critical situations. 
 */
public class MyLayoutInflaterFactory implements LayoutInflaterFactory {
    private AppCompatActivity appCompatActivity;

    public MyLayoutInflaterFactory(AppCompatActivity appCompatActivity) {
        this.appCompatActivity = appCompatActivity;
    }
    
    @Override
    public View onCreateView(View parent, String name, Context context, AttributeSet attrs) {
        View result = null;
        if (TextUtils.equals(name, "DebugDrawerLayout")) {
            result = new DebugDrawerLayout(context, attrs);
        } else if (TextUtils.equals(name, "ScrimInsetsFrameLayout") {
            result = new ScrimInsetsFrameLayout(context, attrs);
        }
        // and so on...
        if (result == null) {
            // Try to let the Activity handle it (inflating fragments from XML)
            result = appCompatActivity.onCreateView(name, context, attrs);
        }
        if (result == null) {
            // Get themed views from app compat
            result = appCompatActivity.getDelegate().createView(parent, name, context, attrs);
        }
        return result;
    }
}

good job! learn a lot, thanks