Question

I’m building a simple paint app and encountering this error given by the logcat:

I’m using the following code:

This SaveDrawing.java serves as the main activity

package com.example.SaveDrawing;

import com.example.SaveDrawing.drawings.DrawingActivity;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;


public class SaveDrawing extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }

    public void onClick(View view){
        switch (view.getId()){
            case R.id.drawBtn:
                //Intent drawIntent = new Intent(this, DrawingActivity.class);
                //startActivity( drawIntent);
                //Toast.makeText(getBaseContext(), "This is the Toast message", Toast.LENGTH_SHORT).show();
                Intent nextActivity = new Intent(SaveDrawing.this, DrawingActivity.class);
                startActivity(nextActivity);
                break;
        }
    }
}

Then the next activity after clicking the button is DrawingActivity.java

package com.example.SaveDrawing.drawings;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.Paint;
import android.graphics.Path;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;

import java.io.File;
import java.io.FileOutputStream;

import com.example.SaveDrawing.R;
import com.example.SaveDrawing.R.id;
import com.example.SaveDrawing.R.layout;

public class DrawingActivity extends Activity implements View.OnTouchListener{
    private DrawingSurface drawingSurface;
    private DrawingPath currentDrawingPath;
    private Paint currentPaint;

    private Button redoBtn;
    private Button undoBtn;

    private static File APP_FILE_PATH = new File("/sdcard/TutorialForAndroidDrawings");


    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.drawing_activity);

        setCurrentPaint();

        drawingSurface = (DrawingSurface) findViewById(R.id.drawingSurface);
        drawingSurface.setOnTouchListener(this);

        redoBtn = (Button) findViewById(R.id.redoBtn);
        undoBtn = (Button) findViewById(R.id.undoBtn);

        redoBtn.setEnabled(false);
        undoBtn.setEnabled(false);

    }

    private void setCurrentPaint(){
        currentPaint = new Paint();
        currentPaint.setDither(true);
        currentPaint.setColor(0xFFFFFF00);
        currentPaint.setStyle(Paint.Style.STROKE);
        currentPaint.setStrokeJoin(Paint.Join.ROUND);
        currentPaint.setStrokeCap(Paint.Cap.ROUND);
        currentPaint.setStrokeWidth(3);

    }




    public boolean onTouch(View view, MotionEvent motionEvent) {
        if(motionEvent.getAction() == MotionEvent.ACTION_DOWN){
            currentDrawingPath = new DrawingPath();
            currentDrawingPath.paint = currentPaint;
            currentDrawingPath.path = new Path();
            currentDrawingPath.path.moveTo(motionEvent.getX(), motionEvent.getY());
            currentDrawingPath.path.lineTo(motionEvent.getX(), motionEvent.getY());

        }else if(motionEvent.getAction() == MotionEvent.ACTION_MOVE){
            currentDrawingPath.path.lineTo(motionEvent.getX(), motionEvent.getY());

        }else if(motionEvent.getAction() == MotionEvent.ACTION_UP){
            currentDrawingPath.path.lineTo(motionEvent.getX(), motionEvent.getY());
            drawingSurface.addDrawingPath(currentDrawingPath);

            undoBtn.setEnabled(true);
            redoBtn.setEnabled(false);
        }

        return true;
    }


    public void onClick(View view){
        switch (view.getId()){
            case R.id.colorRedBtn:
                currentPaint = new Paint();
                currentPaint.setDither(true);
                currentPaint.setColor(0xFFFF0000);
                currentPaint.setStyle(Paint.Style.STROKE);
                currentPaint.setStrokeJoin(Paint.Join.ROUND);
                currentPaint.setStrokeCap(Paint.Cap.ROUND);
                currentPaint.setStrokeWidth(3);
            break;
            case R.id.colorBlueBtn:
                currentPaint = new Paint();
                currentPaint.setDither(true);
                currentPaint.setColor(0xFF00FF00);
                currentPaint.setStyle(Paint.Style.STROKE);
                currentPaint.setStrokeJoin(Paint.Join.ROUND);
                currentPaint.setStrokeCap(Paint.Cap.ROUND);
                currentPaint.setStrokeWidth(3);
            break;
            case R.id.colorGreenBtn:
                currentPaint = new Paint();
                currentPaint.setDither(true);
                currentPaint.setColor(0xFF0000FF);
                currentPaint.setStyle(Paint.Style.STROKE);
                currentPaint.setStrokeJoin(Paint.Join.ROUND);
                currentPaint.setStrokeCap(Paint.Cap.ROUND);
                currentPaint.setStrokeWidth(3);
            break;

            case R.id.undoBtn:
                drawingSurface.undo();
                if( drawingSurface.hasMoreUndo() == false ){
                    undoBtn.setEnabled( false );
                }
                redoBtn.setEnabled( true );
            break;

            case R.id.redoBtn:
                drawingSurface.redo();
                if( drawingSurface.hasMoreRedo() == false ){
                    redoBtn.setEnabled( false );
                }

                undoBtn.setEnabled( true );
            break;
            case R.id.saveBtn:
                final Activity currentActivity  = this;
                Handler saveHandler = new Handler(){
                    @Override
                    public void handleMessage(Message msg) {
                        final AlertDialog alertDialog = new AlertDialog.Builder(currentActivity).create();
                        alertDialog.setTitle("Saved 1");
                        alertDialog.setMessage("Your drawing had been saved :)");
                        alertDialog.setButton("OK", new DialogInterface.OnClickListener() {
                            public void onClick(DialogInterface dialog, int which) {
                                return;
                            }
                        });
                        alertDialog.show();
                    }
                } ;
               new ExportBitmapToFile(this,saveHandler, drawingSurface.getBitmap()).execute();
            break;
        }
    }


    private class ExportBitmapToFile extends AsyncTask<Intent,Void,Boolean> {
        private Context mContext;
        private Handler mHandler;
        private Bitmap nBitmap;

        public ExportBitmapToFile(Context context,Handler handler,Bitmap bitmap) {
            mContext = context;
            nBitmap = bitmap;
            mHandler = handler;
        }

        @Override
        protected Boolean doInBackground(Intent... arg0) {
            try {
                if (!APP_FILE_PATH.exists()) {
                    APP_FILE_PATH.mkdirs();
                }

                final FileOutputStream out = new FileOutputStream(new File(APP_FILE_PATH + "/myAwesomeDrawing.png"));
                nBitmap.compress(Bitmap.CompressFormat.PNG, 90, out);
                out.flush();
                out.close();
                return true;
            }catch (Exception e) {
                e.printStackTrace();
            }
            //mHandler.post(completeRunnable);
            return false;
        }


        @Override
        protected void onPostExecute(Boolean bool) {
            super.onPostExecute(bool);
            if ( bool ){
                mHandler.sendEmptyMessage(1);
            }
        }
    }
}

AndroidManifest.xml

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

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

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

    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".SaveDrawing"
                  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=".DrawingActivity" android:screenOrientation="landscape" ></activity>
        <activity android:name=".drawings.DrawingActivity"/>
    </application>
</manifest>

I have the following in my explorer. I’m not so sure if I got a wrong file structure.

Anyone can help me? I’m kinda new to java and android programming. Many thanks!!! 🙂

Answer 1

remove <activity android:name=".DrawingActivity" android:screenOrientation="landscape" ></activity> from your manifest as there is no such activity. there is only DrawingActivity in your project structure. Then clean build Run.
Also another possible problem could having an Activity Class name SaveDrawing in the package. You should try to rename the package, update relevant changes to the manifest and try running the app again..