Add setDisplayHomeAsUpEnabled(true)
Toolbar toolbar = findViewById(R.id.toolbar); ActionBar actionBar = getSupportActionBar(); if (actionBar != null) { actionBar.setDisplayHomeAsUpEnabled(true); }
Handle the back button
public boolean onSupportNavigateUp() { onBackPressed(); return true; }

In Kotlin it would be -----
private fun setupToolbar(){ toolbar.title = getString(R.string.YOUR_TITLE) setSupportActionBar(toolbar) supportActionBar?.setDisplayHomeAsUpEnabled(true) supportActionBar?.setDisplayShowHomeEnabled(true) }
// don't forget click listener for back button override fun onSupportNavigateUp(): Boolean { onBackPressed() return true }