android - Error: Could not find or load main class com.example.pdfone.MainActivity

Question

I'm new user in android and I try to view a pdf file using itext jar file. My code is:

package com.example.pdfone;

public class MainActivity {

    public static final String RESULT = "Workspace/one.pdf";

    public static void main(String[] args) throws DocumentException, IOException {
        Document document = new Document();
        PdfWriter.getInstance(document, new FileOutputStream(RESULT));
        document.open();
        document.add(new Paragraph("Hello World!"));
        document.close();
    }

}

But when I run this program it gives me Error: Could not find or load main class com.example.pdfone.MainActivity error in console

What can I do? Please help me. Thank you in advance

Answer 1

You need to learn Android first.

Your class needs to extend Activity class.

And iText can only create pdf file, viewing is not possible. Reading is possible. Use Adobe Acrobat or any other PDF tools in Android to view it.

Sample Solutions is as below for PDF Read and Write in Android

100% Working Code Screenshots as below,

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:layout_gravity="center"
    tools:context=".MainActivity" >
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:textAlignment="center"
        android:text="Android Read/Write File" />

    <EditText
        android:id="@+id/fname"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:hint="File Name"
        android:text="sample_pdf_file" />

    <EditText
        android:id="@+id/ftext"
        android:layout_width="fill_parent"
        android:layout_height="100px"
        android:hint="File Text"
        android:text="Hello World" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/btnwrite"
        android:text="Write File" />

    <EditText
        android:id="@+id/fnameread"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:hint="File Name"
        android:text="sample_pdf_file" />

       <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/btnread"
        android:text="Read File" />
       <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:id="@+id/filecon" />
</LinearLayout>

FileOperations.java

package com.example.readwrite;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.StringWriter;

import android.util.Log;

import com.itextpdf.text.Document;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.Paragraph;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.PdfWriter;
import com.itextpdf.text.pdf.parser.PdfReaderContentParser;
import com.itextpdf.text.pdf.parser.SimpleTextExtractionStrategy;
import com.itextpdf.text.pdf.parser.TextExtractionStrategy;

public class FileOperations {
    public FileOperations() {
    }

    public Boolean write(String fname, String fcontent) {
        try {
            String fpath = "/sdcard/" + fname + ".pdf";
            File file = new File(fpath);
            // If file does not exists, then create it
            if (!file.exists()) {
                file.createNewFile();
            }

            // step 1
            Document document = new Document();
            // step 2
            PdfWriter.getInstance(document,
                    new FileOutputStream(file.getAbsoluteFile()));
            // step 3
            document.open();
            // step 4
            document.add(new Paragraph("Hello World!"));
            document.add(new Paragraph("Hello World2!"));
            // step 5
            document.close();

            Log.d("Suceess", "Sucess");
            return true;
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        } catch (DocumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return false;
        }
    }

    public String read(String fname) {
        BufferedReader br = null;
        String response = null;
        try {
            StringBuffer output = new StringBuffer();
            String fpath = "/sdcard/" + fname + ".pdf";

            PdfReader reader = new PdfReader(new FileInputStream(fpath));
            PdfReaderContentParser parser = new PdfReaderContentParser(reader);

            StringWriter strW = new StringWriter();

            TextExtractionStrategy strategy;
            for (int i = 1; i <= reader.getNumberOfPages(); i++) {
                strategy = parser.processContent(i,
                        new SimpleTextExtractionStrategy());

                strW.write(strategy.getResultantText());

            }

            response = strW.toString();

        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
        return response;
    }
}

MainActivity.java

package com.example.readwrite;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {
    EditText fname, fcontent, fnameread;
    Button write, read;
    TextView filecon;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        fname = (EditText) findViewById(R.id.fname);
        fcontent = (EditText) findViewById(R.id.ftext);
        fnameread = (EditText) findViewById(R.id.fnameread);
        write = (Button) findViewById(R.id.btnwrite);
        read = (Button) findViewById(R.id.btnread);
        filecon = (TextView) findViewById(R.id.filecon);
        write.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                String filename = fname.getText().toString();
                String filecontent = fcontent.getText().toString();
                FileOperations fop = new FileOperations();
                fop.write(filename, filecontent);
                if (fop.write(filename, filecontent)) {
                    Toast.makeText(getApplicationContext(),
                            filename + ".pdf created", Toast.LENGTH_SHORT)
                            .show();
                } else {
                    Toast.makeText(getApplicationContext(), "I/O error",
                            Toast.LENGTH_SHORT).show();
                }
            }
        });
        read.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                String readfilename = fnameread.getText().toString();
                FileOperations fop = new FileOperations();
                String text = fop.read(readfilename);
                if (text != null) {
                    filecon.setText(text);
                } else {
                    Toast.makeText(getApplicationContext(), "File not Found",
                            Toast.LENGTH_SHORT).show();
                    filecon.setText(null);
                }
            }
        });
    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.readwrite"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="18" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
        <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

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

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

</manifest>

Make sure you have the itextpdf-5.5.1.jar in the right location as below,