android startActivity로 화면 이동시 back 버튼 안보일 때

How to showing back button when activity moving

 <activity
    ...
    android:name=".SecondActivity"
    android:parentActivityName=".MainActivity" >

1. 위에 처럼 parent를 등록한다.

1. add as above in manifest.xml

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    // Respond to the action bar's Up/Home button
    case android.R.id.home:
        onBackPressed();
        return true;
    }
    return super.onOptionsItemSelected(item);
}




2. 위에 해당 코드 추가.

2. add as above in your second activity

kotlin

override fun onOptionsItemSelected(item: MenuItem): Boolean {
    when (item.getItemId()) {
        android.R.id.home -> {
            onBackPressed()
            return true
        }
    }
    return super.onOptionsItemSelected(item)
}

출처: https://stackoverflow.com/questions/36457564/display-back-button-of-action-bar-is-not-going-back-in-android