In this tutorial we will add a back button in action bar, when it is clicked it will go to previous activity(the app will close if this was launcher activity). We will go from main activity to new activity by clicking button in main activity. In new activity we will add a back button to actionbar when that button is clicked the main activity will appear..
Example
Step 1: Create a new Project or open new project
Step 2: Create New Activity File>New>Activity>EmptyActivity
Step 3: Code:
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
tools:context=".MainActivity">
<Button
android:id="@+id/startActBtn"
android:text="New Activity"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
MainActivity.kt
package com.jigopost.myapplication
import android.content.Intent
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
//button
val mStartActBtn = findViewById<Button>(R.id.startActBtn)
//handle button click
mStartActBtn.setOnClickListener {
//start activity intent
startActivity(Intent(this@MainActivity, NewActivity::class.java))
}
}
}
activity_new.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:gravity="center"
tools:context=".NewActivity">
<TextView
android:text="Click back buttoon of actionbar"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
NewActivity.kt
package com.jigopost.myapplication
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
class NewActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_new)
//actionbar
val actionbar = supportActionBar
//set actionbar title
actionbar!!.title = "New Activity"
//set back button
actionbar.setDisplayHomeAsUpEnabled(true)
actionbar.setDisplayHomeAsUpEnabled(true)
}
override fun onSupportNavigateUp(): Boolean {
onBackPressed()
return true
}
}
Step 4: Run Project
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