Draw rounded corner line along path, with CornerPathEffect.

package com.example.androidview;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.CornerPathEffect;
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);

  path = new Path();
  path.moveTo(50, 50);
  path.lineTo(50, 500);
  path.lineTo(200, 500);
  path.lineTo(200, 300);
  path.lineTo(350, 300);

  float radius = 50.0f;
  
  CornerPathEffect cornerPathEffect =
    new CornerPathEffect(radius);

  paint.setPathEffect(cornerPathEffect);

 }

 @Override
 protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
  canvas.drawPath(path, paint);

 }

}