Draw on Canvas directly, in custom View.

Create a new class MyView extends View, it's our custom View. Override the onDraw(Canvas canvas) method to draw on Canvas directly.

package com.AndroidMyCanvas;

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.View;

public class MyView extends View {
 
 Paint paint;
 Path path;

 public MyView(Context context) {
  super(context);
  init();
 }

 public MyView(Context context, AttributeSet attrs) {
  super(context, attrs);
  init();
 }

 public MyView(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
  init();
 }
 
 private void init(){
  paint = new Paint();
  paint.setColor(Color.BLUE);
  paint.setStrokeWidth(10);
  paint.setStyle(Paint.Style.STROKE);

 }

 @Override
 protected void onDraw(Canvas canvas) {
  // TODO Auto-generated method stub
  super.onDraw(canvas);
  
  path = new Path();
  path.moveTo(50, 50);
  path.lineTo(50, 500);
  path.lineTo(200, 500);
  path.lineTo(200, 300);
  path.lineTo(350, 300);
  
  canvas.drawPath(path, paint);

 }

}

Modify main Java activity to setContentView() using our custom View, MyView.

package com.AndroidMyCanvas;

import android.app.Activity;
import android.os.Bundle;

public class AndroidMyCanvasActivity extends Activity {
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(new MyView(this));
  }
}