Displaying Images in Android using Java

Question

I am splitting this off from my other thread here: Display image in popout window after button is clicked -- Android/Java

The old thread got very convoluted and confusing, and a bit off-topic, so I wanted to create another one that is clearer with more information.

I am trying to display an image in Android using an image file path that changes every time the app is run. I know there are ways to declare resources in the XML layout file, but since the picture I'd like to display is taken from the camera, I can't do it that way. I need to be able to display the image without hardcoding it.

The following is the code that I have:

photo_viewer.xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/pictureViewer"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" >

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:contentDescription="@string/viewImage" />

</RelativeLayout>

Java method to display image:

public void viewPhoto(String file){ 
    ImageView imageView = new ImageView(getApplicationContext());
    LayoutParams lp = new LayoutParams(LayoutParams.WRAP_CONTENT,
        LayoutParams.WRAP_CONTENT);
    Bitmap image = BitmapFactory.decodeFile(file);
    imageView.setImageBitmap(image);
    RelativeLayout rl = (RelativeLayout)findViewById(R.id.pictureViewer);
    rl.addView(imageView, lp);
}

However, when I run the above code the application crashes, saying it has stopped working. "file" is a string denoting the directory where the image from the camera is stored, and I know this part is correct. I can use it (using a different method) to change the wallpaper. It's just displaying it that is causing me trouble. I have tried various methods to simply display the image (dialogs, "drawable"s, bitmap factory, etc) and had the same problem with all of them. I feel like it's something simple that I have missed, since I'm new to Android app development. I'm hoping one of you folks might be able to shed some light on this.

EDIT:

I have decided to try another route, but I am still getting a null pointer exception. Here is all my code:

main class, viewPhoto method:

/* View photo */
public void viewPhoto(String file){ 
    Intent imageView = new Intent(this, PhotoViewer.class);
    imageView.putExtra("directory", file);
    startActivity(imageView);
}

PhotoViewer class:

package com.androidproject;

import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.widget.ImageView;
import android.widget.RelativeLayout;

public class PhotoViewer extends Activity {

    public String file;
    ImageView image;

    @Override
    protected void onCreate(Bundle bundle) {
        super.onCreate(bundle);
        setContentView(R.layout.photo_viewer);

        //get file path of image
        Bundle extras = getIntent().getExtras();
        file = extras.getString("directory");

        Drawable drawable = Drawable.createFromPath(file);
        image.setImageDrawable(drawable);
    }
}

photo_viewer.xml (created using the Eclipse tool, so it's not just any xml file)

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/photo_viewer"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".PhotoViewer" >

    <ImageView 
        android:id="@+id/imageView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" 
        android:contentDescription="@string/viewImage"/>

</RelativeLayout>

Project manifest:

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.androidproject"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />

    <uses-permission android:name="android.permission.CAMERA"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.SET_WALLPAPER" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".Main"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity
            android:name=".PhotoViewer"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="com.androidproject.PhotoViewer" />

                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </activity>
    </application>

</manifest>

The app continues to crash and tell me "unfortunately it stopped working". Here's the logcat of the error:

As always, help is appreciated!

Answer 1

The null pointer exception is because

 Drawable drawable = Drawable.createFromPath(file);
 image.setImageDrawable(drawable);

is referencing an uninitiated variable (image) which is null

My best guess would be that to eliminate said error you'd want to initiate the variable

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