无法创建默认构造函数

Question

编辑：@spiderman感谢您的努力。我通过解决我在上一条评论中所做的事情（关于使用该类作为自定义视图的教程）修复了错误消息，所以我想我会没事的。

Android给了我一个零构造函数错误，所以我现在尝试编写一个默认构造函数，如下所示：

public SignatureActivity() {
    super("SignatureActivity");
}

但是我收到一个错误，告诉我我无法将视图对象放入字符串中 - View in View无法应用于java.lang.String。

如何解决这个问题，以便能够成功运行我的代码？

这是班级：

import android.provider.MediaStore;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.util.AttributeSet;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;





public class SignatureActivity extends View {

public SignatureActivity() {
    super("SignatureActivity");
}



private Paint paint = new Paint();
private Path path = new Path();

protected void onDraw(Canvas canvas) {
    canvas.drawPath(path, paint);
}

public SignatureActivity(Context context, AttributeSet attrs) {

    super(context, attrs);

    paint.setAntiAlias(true);
    paint.setStrokeWidth(5f);
    paint.setColor(Color.BLACK);
    paint.setStyle(Paint.Style.STROKE);
    paint.setStrokeJoin(Paint.Join.ROUND);

}


@Override
public boolean onTouchEvent(MotionEvent event) {

    float eventX = event.getX();
    float eventY = event.getY();

    Log.v("SignatureActivity", "This is onTouchEvent");

    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            // Set a new starting point
            path.moveTo(eventX, eventY);
            return true;
        case MotionEvent.ACTION_MOVE:
            // Connect the points
            path.lineTo(eventX, eventY);
            break;
        default:
            return false;
    }

    // Makes our view repaint and call onDraw
    invalidate();
    return true;
}


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



} */



/**@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_signature, menu);
    return true;
}*/

/**@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}*/




}