ComPDFKit
Contact Sales
PDF SDKIDPConversion SDK
PDF SDK
DownloadFAQTechnical Support
Guides

How to Make an Android PDF Viewer in Java ​

This section will help you to quickly get started with ComPDFKit PDF SDK to make an Android app in Java with step-by-step instructions. Through the following steps, you will get a simple application that can display the contents of a specified PDF file.

Create a New Project ​

  1. Use Android Studio to create a Phone & Tablet project. Here we create a No Activity project.

create_project.png

Add the ComPDFKit PDF SDK Package ​

The first step we need to take is to import the ComPDFKit PDF SDK. You can integrate it in two ways: using Integrate With Gradle or Integrate Manually.

Integrate With Gradle ​

  1. Open the settings.gradle file located in your project's root directory and add the mavenCentral repository:
diff
dependencyResolutionManagement {
    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
    repositories {
        google()
+       mavenCentral()
    }
}
  1. Open the build.gradle file in the application module directory:
2.4.2.1-1

Edit it and add the complete ComPDFKit SDK dependency:

groovy
dependencies {
  implementation 'com.compdf:compdfkit:2.2.0'
  implementation 'com.compdf:compdfkit-ui:2.2.0'
}
  1. Apply for read and write permissions in AndroidManifest.xml:
xml
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

Note: On your apps that target Android 6.0 or higher, make sure to check for and request read and write permissions to external storage at runtime.

  1. If you use an online license, please add network access permissions in AndroidManifest.xml:
xml
<uses-permission android:name="android.permission.INTERNET"/>

Integrate Manually ​

  1. Copy "ComPDFKit.aar" and "ComPDFKit-UI.aar" to the "libs" directory of the app.

libs.png

  1. Add the following code into the app dictionary’s "build.gradle" file:
groovy
...
dependencies {
    /*ComPDFKit SDK*/
    implementation(fileTree('libs'))
    ...
}
...
  1. Add ComPDFKit PDF SDK for Android as a dependency to the project. Inside the app dictionary’s "build.gradle", add "ComPDFKit.aar", "ComPDFKit-UI.aar", and the related support libraries to the dependencies. For simplicity, update the dependencies as follows:
groovy
dependencies {
    ...
    //glide
    implementation 'com.github.bumptech.glide:glide:4.12.0'
    annotationProcessor 'com.github.bumptech.glide:compiler:4.12.0'

    implementation 'androidx.documentfile:documentfile:1.0.1'
}
  1. Apply for read and write permissions in AndroidManifest.xml:
xml
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

Note: On your apps that target Android 6.0 or higher, make sure to check for and request read and write permissions to external storage at runtime.

  1. If you use an online license, please add network access permissions in AndroidManifest.xml:
xml
<uses-permission android:name="android.permission.INTERNET"/>

Apply the License Key ​

Add this license in the AndroidManifest.xml of the main module. In version 1.13.0, we introduced a brand-new online authentication license scheme for ComPDFKit SDK. By default, the SDK performs online authentication. If you are using a version prior to 1.13.0, please refer to the following example to configure the SDK for offline authentication mode:

  • Online license
xml
<!-- Each ComPDFKit license is bound to a specific applicationId -->
<!-- For example: com.compdfkit.pdfviewer -->
<meta-data
    android:name="compdfkit_key_online"
    android:value="Your ComPDFKit Key" />

You can also initialize ComPDFKit SDK in code using:

java
CPDFSdk.init(context, "your compdfkit license", false);
  • Offline license
xml
<!-- Each ComPDFKit license is bound to a specific applicationId -->
<!-- For example: com.compdfkit.pdfviewer -->
<meta-data
    android:name="compdfkit_key"
    android:value="Your ComPDFKit Key" />

You can also initialize ComPDFKit SDK in code using:

java
CPDFSdk.init(context, "your compdfkit license");

Add Proguard Rules ​

In the proguard-rules.pro file, please add the obfuscation configuration information for compdfkit as follows:

-keep class com.compdfkit.ui.** {*;}
-keep class com.compdfkit.core.** {*;}

Display a PDF Document ​

  1. Copy a PDF document into the assets directory of your Android project. For example, import the file "Quick Start Guide.pdf" to the path src/main/assets.

structure.png

  1. Create a new Empty Activity under your package, and set the activity name to MainActivity.

new_activity.png

Android Studio will automatically generate a source file called "MainActivity.java" and a layout file called "activity_main.xml".

The source file:

activity_java.png

The layout file:

layout.png

  1. Create a CPDFReaderView in your "activity_main.xml" to display the contents of the PDF document:
xml
<!-- Your activity_main.xml file -->

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <!-- Create a CPDFReaderView -->
    <com.compdfkit.ui.reader.CPDFReaderView
        android:id="@+id/readerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

Get the CPDFReaderView from the layout or create a CPDFReaderView directly in the code in the corresponding MainActivity.java file:

Java
// Your MainActivity.java file

package com.compdfkit.pdfviewer;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import com.compdfkit.ui.reader.CPDFReaderView;

public class MainActivity extends AppCompatActivity {

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

        // Get CPDFReaderView from xml.
        CPDFReaderView readerView = findViewById(R.id.readerview);
        // Code to create CPDFReaderView.
        // CPDFDocument readerView = new CPDFReaderView(content);
    }
}
kotlin
// Your MainActivity.kt file
package com.compdfkit.pdfviewer

import androidx.appcompat.app.AppCompatActivity

import android.os.Bundle
import com.compdfkit.ui.reader.CPDFReaderView

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // Get CPDFReaderView from xml.
        val readerView = findViewById<CPDFReaderView>(R.id.readerview)
        // Code to create CPDFReaderView.
        // CPDFDocument readerView = new CPDFReaderView(content);
    }
}
  1. Open the document. This is a time-consuming process, so it needs to be executed in a sub-thread. After the document is opened successfully, the UI that renders the PDF is initiated:
Java
// Your MainActivity.java file

... //imports

public class MainActivity extends AppCompatActivity {

    // Copy the PDF file from the assets folder to the cache folder.
    private void copyPdfFromAssetsToCache(String fileName) {
        try {
            InputStream inputStream = getAssets().open(fileName);
            File outputFile = new File(getCacheDir(), fileName);
            FileOutputStream outputStream = new FileOutputStream(outputFile);

            byte[] buffer = new byte[1024];
            int bytesRead;
            while ((bytesRead = inputStream.read(buffer)) != -1) {
                outputStream.write(buffer, 0, bytesRead);
            }

            inputStream.close();
            outputStream.flush();
            outputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
  
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        CPDFReaderView readerView = findViewById(R.id.readerview);
        // Code to create CPDFReaderView.
        // CPDFDocument readerView = new CPDFReaderView(content);

        //Create a document object.
        CPDFDocument document = new CPDFDocument(this);
    

        new Thread(() -> {
            String fileName = "Quick Start Guide.pdf";
            copyPdfFromAssetsToCache(fileName);

            File file = new File(getCacheDir(), fileName);
            String filePath = file.getAbsolutePath();

            //Open document.
            CPDFDocument.PDFDocumentError error = document.open(filePath);
            if (error == CPDFDocument.PDFDocumentError.PDFDocumentErrorPassword) {
                //The document is encrypted and requires a password to open.
                error = document.open(filePath, "password");
            }

            if (error == CPDFDocument.PDFDocumentError.PDFDocumentErrorSuccess) {
                //The document is opened successfully and data can be parsed and manipulated.
            } else {
                //The PDF file failed to open. You can refer to the API file for specific error
            }
        }).start();
    }
}
kotlin
// Your MainActivity.kt file

... //imports

class MainActivity : AppCompatActivity() {

  // Copy the PDF file from the assets folder to the cache folder.
  private fun copyPdfFromAssetsToCache(fileName: String) {
    try {
      val inputStream = assets.open(fileName)
      val outputFile = File(cacheDir, fileName)
      val outputStream = FileOutputStream(outputFile)

      val buffer = ByteArray(1024)
      var bytesRead: Int
      while (inputStream.read(buffer).also { bytesRead = it } != -1) {
        outputStream.write(buffer, 0, bytesRead)
      }
      inputStream.close()
      outputStream.flush()
      outputStream.close()
    } catch (e: IOException) {
      e.printStackTrace()
    }
  }

  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    val readerView = findViewById<CPDFReaderView>(R.id.readerview)
    // Code to create CPDFReaderView.
    // CPDFDocument readerView = new CPDFReaderView(content);

    //Create a document object.
    val document = CPDFDocument(this)

    Thread {
      val fileName = "Quick Start Guide.pdf"
      copyPdfFromAssetsToCache(fileName)

      val file = File(cacheDir, fileName)
      val filePath = file.absolutePath

      //Open document.
      var error = document.open(filePath)
      if (error == CPDFDocument.PDFDocumentError.PDFDocumentErrorPassword) {
        //The document is encrypted and requires a password to open.
        error = document.open(filePath, "password")
      }
      if (error == CPDFDocument.PDFDocumentError.PDFDocumentErrorSuccess) {
        //The document is opened successfully and data can be parsed and manipulated.
      } else {
        //The PDF file failed to open. You can refer to the API file for specific error
      }
    }.start()
  }
}
  1. Set the basic properties of CPDFReaderView :
Java
// Your MainActivity.java file

... // imports

public class MainActivity extends AppCompatActivity {
    // Create a handler to run the code on the main thread.
    private Handler mainThreadHandler = new Handler(Looper.getMainLooper());
...
    if (error == CPDFDocument.PDFDocumentError.PDFDocumentErrorSuccess) {
        // The document is opened successfully and data can be parsed and manipulated.
        mainThreadHandler.post(() -> {
            // Set the document content for UI.
            readerView.setPDFDocument(document);
        });
    } else {
        // The PDF file failed to open. You can refer to the API file for specific error
    }
...
}
kotlin
// Your MainActivity.kt file

... // imports

public class MainActivity : AppCompatActivity() {
    // Create a handler to run the code on the main thread.
    private var mainThreadHandler =  Handler(Looper.getMainLooper());
    ...
    if (error == CPDFDocument.PDFDocumentError.PDFDocumentErrorSuccess) {
        // The document is opened successfully and data can be parsed and manipulated.
        mainThreadHandler.post {
            // Set the document content for UI.
            readerView.setPDFDocument(document);
        }
    } else {
        // The PDF file failed to open. You can refer to the API file for specific error
    }
    ...
}
  1. Your code may resemble the following at this stage:
Java
// Your MainActivity.java file

... // imports

public class MainActivity extends AppCompatActivity {
    // Create a handler to run the code on the main thread.
    private Handler mainThreadHandler = new Handler(Looper.getMainLooper());
    // Copy the PDF file from the assets folder to the cache folder.
    private void copyPdfFromAssetsToCache(String fileName) {
        try {
            InputStream inputStream = getAssets().open(fileName);
            File outputFile = new File(getCacheDir(), fileName);
            FileOutputStream outputStream = new FileOutputStream(outputFile);

            byte[] buffer = new byte[1024];
            int bytesRead;
            while ((bytesRead = inputStream.read(buffer)) != -1) {
                outputStream.write(buffer, 0, bytesRead);
            }

            inputStream.close();
            outputStream.flush();
            outputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

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

        CPDFReaderView readerView = findViewById(R.id.readerview);

        //Create a document object.
        CPDFDocument document = new CPDFDocument(this);

        new Thread(() -> {
            String fileName = "Quick Start Guide.pdf";
            copyPdfFromAssetsToCache(fileName);

            File file = new File(getCacheDir(), fileName);
            String filePath = file.getAbsolutePath();

            //Open document.
            CPDFDocument.PDFDocumentError error = document.open(filePath);
            if (error == CPDFDocument.PDFDocumentError.PDFDocumentErrorPassword) {
                //The document is encrypted and requires a password to open.
                error = document.open(filePath, "password");
            }

            if (error == CPDFDocument.PDFDocumentError.PDFDocumentErrorSuccess) {
                //The document is opened successfully and data can be parsed and manipulated.
                mainThreadHandler.post(() -> {
                    //Set the document to the reader view.
                    readerView.setPDFDocument(document);
                });
            } else {
                //The PDF file failed to open. You can refer to the API file for specific error
            }
        }).start();
    }
}
kotlin
// Your MainActivity.kt file

... // imports

class MainActivity : AppCompatActivity() {
    // Create a handler to run the code on the main thread.
    private val mainThreadHandler = Handler(Looper.getMainLooper())

    // Copy the PDF file from the assets folder to the cache folder.
    private fun copyPdfFromAssetsToCache(fileName: String) {
        try {
            val inputStream = assets.open(fileName)
            val outputFile = File(cacheDir, fileName)
            val outputStream = FileOutputStream(outputFile)
            val buffer = ByteArray(1024)
            var bytesRead: Int
            while (inputStream.read(buffer).also { bytesRead = it } != -1) {
                outputStream.write(buffer, 0, bytesRead)
            }
            inputStream.close()
            outputStream.flush()
            outputStream.close()
        } catch (e: IOException) {
            e.printStackTrace()
        }
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val readerView = findViewById<CPDFReaderView>(R.id.readerview)

        //Create a document object.
        val document = CPDFDocument(this)
        Thread {
            val fileName = "Quick Start Guide.pdf"
            copyPdfFromAssetsToCache(fileName)
            val file = File(cacheDir, fileName)
            val filePath = file.absolutePath

            //Open document.
            var error = document.open(filePath)
            if (error == PDFDocumentError.PDFDocumentErrorPassword) {
                //The document is encrypted and requires a password to open.
                error = document.open(filePath, "password")
            }
            if (error == PDFDocumentError.PDFDocumentErrorSuccess) {
                //The document is opened successfully and data can be parsed and manipulated.
                mainThreadHandler.post {
                    //Set the document to the reader view.
                    readerView.pdfDocument = document
                }
            } else {
                //The PDF file failed to open. You can refer to the API file for specific error
            }
        }.start()
    }
}
xml
<!-- Your activity_main.xml file -->
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <com.compdfkit.ui.reader.CPDFReaderView
        android:id="@+id/readerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</androidx.constraintlayout.widget.ConstraintLayout>
  1. Run the application.
2.4.2.1-1

Now, with the help of ComPDFKit, you can get a simple application to display a PDF file.

Troubleshooting ​

  1. Unable to Open the PDF Files

    The license we provide to you is tied to your application ID, so ensure that the license acquired matches your application ID.

  2. Other Problems

    If you meet some other problems when integrating our ComPDFKit PDF SDK for Android, feel free to contact ComPDFKit team.