Java – Jackson unable to load JDK7 types on Android

androidjacksonjavajava-7kotlin

I use Jackson 2.8.2 in my Android app to deserialize JSON. The deserialization itself works, however, I can see the following warning in the application log:

Unable to load JDK7 types (annotations, java.nio.file.Path): no Java7 support added

Proguard is disabled, sourceCompatibility is set to '1.7'. How can I add these seemingly missing types to my build?

Best Answer

First, your sourceCompatibility setting of 1.7 doesn't mean anything about the runtime environment, so it has no impact on this message.

This is purely a "do these classes exist at the time Jackson initializes this class" issue -- and they do not exist in some combination. And maybe that is ok, if you do not use the Java 7 java.nio.file.Path class then you should have no issue with this logged warning message. Because that is what this warning is about, Jackson supporting serialization/deserialization of this specific class.

Looking at Android java.nio.* packages, it does not have java.nio.file.* packages at any API level. So that explains why you see the warning message. And since you can't use java.nio.file.Path anyway, this isn't even a real issue other than an annoying logging message.

If this message is bothersome you can always set the Java Util Logging level for logger com.fasterxml.jackson.databind.ext.Java7Support to be level ERROR. Then you will no longer see these warning messages.

More about the logged message:

In Jackson 2.8.x this support for Java 7 class java.nio.file.Path is all loading from the same JAR file and is built-in. One class dynamically checks if another can load without error:

Class<?> cls = Class.forName("com.fasterxml.jackson.databind.ext.Java7SupportImpl");

The only way this can fail is if something is stripping this class from the final set of classes. Or one of these classes it depends on is missing from the runtime:

import java.beans.ConstructorProperties;
import java.beans.Transient;
import java.nio.file.Path;

If any of those are missing then you will see the logged error message. So one of these is true:

one or more of the JDK 7 classes are missing at runtime
com.fasterxml.jackson.databind.ext.Java7SupportImpl is missing at runtime

Neither of those causes are Jackson's fault, they are something about your runtime environment (i.e. they don't exist in Android API's), or Proguard stripping classes it doesn't think are used.

Related Solutions

Android – How to lazy load images in ListView in Android

Here's what I created to hold the images that my app is currently displaying. Please note that the "Log" object in use here is my custom wrapper around the final Log class inside Android.

package com.wilson.android.library;

/*
 Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements.  See the NOTICE file
distributed with this work for additional information
regarding copyright ownership.  The ASF licenses this file
to you under the Apache License, Version 2.0 (the
"License"); you may not use this file except in compliance
with the License.  You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied.  See the License for the
specific language governing permissions and limitations
under the License.
*/
import java.io.IOException;

public class DrawableManager {
    private final Map<String, Drawable> drawableMap;

    public DrawableManager() {
        drawableMap = new HashMap<String, Drawable>();
    }

    public Drawable fetchDrawable(String urlString) {
        if (drawableMap.containsKey(urlString)) {
            return drawableMap.get(urlString);
        }

        Log.d(this.getClass().getSimpleName(), "image url:" + urlString);
        try {
            InputStream is = fetch(urlString);
            Drawable drawable = Drawable.createFromStream(is, "src");


            if (drawable != null) {
                drawableMap.put(urlString, drawable);
                Log.d(this.getClass().getSimpleName(), "got a thumbnail drawable: " + drawable.getBounds() + ", "
                        + drawable.getIntrinsicHeight() + "," + drawable.getIntrinsicWidth() + ", "
                        + drawable.getMinimumHeight() + "," + drawable.getMinimumWidth());
            } else {
              Log.w(this.getClass().getSimpleName(), "could not get thumbnail");
            }

            return drawable;
        } catch (MalformedURLException e) {
            Log.e(this.getClass().getSimpleName(), "fetchDrawable failed", e);
            return null;
        } catch (IOException e) {
            Log.e(this.getClass().getSimpleName(), "fetchDrawable failed", e);
            return null;
        }
    }

    public void fetchDrawableOnThread(final String urlString, final ImageView imageView) {
        if (drawableMap.containsKey(urlString)) {
            imageView.setImageDrawable(drawableMap.get(urlString));
        }

        final Handler handler = new Handler() {
            @Override
            public void handleMessage(Message message) {
                imageView.setImageDrawable((Drawable) message.obj);
            }
        };

        Thread thread = new Thread() {
            @Override
            public void run() {
                //TODO : set imageView to a "pending" image
                Drawable drawable = fetchDrawable(urlString);
                Message message = handler.obtainMessage(1, drawable);
                handler.sendMessage(message);
            }
        };
        thread.start();
    }

    private InputStream fetch(String urlString) throws MalformedURLException, IOException {
        DefaultHttpClient httpClient = new DefaultHttpClient();
        HttpGet request = new HttpGet(urlString);
        HttpResponse response = httpClient.execute(request);
        return response.getEntity().getContent();
    }
}

Android – How to close/hide the Android soft keyboard programmatically

You can force Android to hide the virtual keyboard using the InputMethodManager, calling hideSoftInputFromWindow, passing in the token of the window containing your focused view.

// Check if no view has focus:
View view = this.getCurrentFocus();
if (view != null) {  
    InputMethodManager imm = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
    imm.hideSoftInputFromWindow(view.getWindowToken(), 0);
}

This will force the keyboard to be hidden in all situations. In some cases, you will want to pass in InputMethodManager.HIDE_IMPLICIT_ONLY as the second parameter to ensure you only hide the keyboard when the user didn't explicitly force it to appear (by holding down the menu).

Note: If you want to do this in Kotlin, use: context?.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager

Kotlin Syntax

// Only runs if there is a view that is currently focused
this.currentFocus?.let { view ->
    val imm = getSystemService(Context.INPUT_METHOD_SERVICE) as? InputMethodManager
    imm?.hideSoftInputFromWindow(view.windowToken, 0)
}

Best Answer

Related Solutions

Android – How to lazy load images in ListView in Android

Android – How to close/hide the Android soft keyboard programmatically

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