I am new to Android programming and I am confused by the activity life cycle. I have read a few articles on it but I still can't wrap my mind around how to make the back button work.
I have a Main Activity with buttons that go to new Activities and this works fine however when I use the device back button when it goes back to the Main Activity the buttons are disabled. I think this is because I need to re-initialize the Main Activity but I don't know how. I tries OnResume but it did not work. Here are my two activities:
package com.rootsofempathy.recoveryjunior
import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.ImageButton
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val button_gr = findViewById<ImageButton>(R.id.gr_btn)
button_gr.setOnClickListener {
println("Button Clicked")
val activity2Intent = Intent(applicationContext, getting_ready::class.java)
startActivity(activity2Intent)
}
val buttonOne = findViewById<ImageButton>(R.id.theme1_btn)
buttonOne.setOnClickListener {
val activity2Intent = Intent(applicationContext, Theme_One::class.java)
startActivity(activity2Intent)
}
val buttonTwo = findViewById<ImageButton>(R.id.theme2_btn)
buttonTwo.setOnClickListener {
val activity2Intent = Intent(applicationContext, Theme_Two::class.java)
startActivity(activity2Intent)
}
val buttonThree = findViewById<ImageButton>(R.id.theme3_btn)
buttonThree.setOnClickListener {
val activity2Intent = Intent(applicationContext, Theme_Three::class.java)
startActivity(activity2Intent)
}
val buttonFour = findViewById<ImageButton>(R.id.theme4_btn)
buttonFour.setOnClickListener {
val activity2Intent = Intent(applicationContext, Theme_Four::class.java)
startActivity(activity2Intent)
}
val buttonFive = findViewById<ImageButton>(R.id.theme5_btn)
buttonFive.setOnClickListener {
val activity2Intent = Intent(applicationContext, Theme_Five::class.java)
startActivity(activity2Intent)
}
val buttonSix = findViewById<ImageButton>(R.id.theme6_btn)
buttonSix.setOnClickListener {
val activity2Intent = Intent(applicationContext, Theme_Six::class.java)
startActivity(activity2Intent)
}
val buttonSeven = findViewById<ImageButton>(R.id.theme7_btn)
buttonSeven.setOnClickListener {
val activity2Intent = Intent(applicationContext, Theme_Seven::class.java)
startActivity(activity2Intent)
}
val buttonEight = findViewById<ImageButton>(R.id.theme8_btn)
buttonEight.setOnClickListener {
val activity2Intent = Intent(applicationContext, Theme_Eight::class.java)
startActivity(activity2Intent)
}
val buttonNine = findViewById<ImageButton>(R.id.theme9_btn)
buttonNine.setOnClickListener {
val activity2Intent = Intent(applicationContext, Theme_Nine::class.java)
startActivity(activity2Intent)
}
val buttonTen = findViewById<ImageButton>(R.id.theme10_btn)
buttonTen.setOnClickListener {
val activity2Intent = Intent(applicationContext, Theme_Ten::class.java)
startActivity(activity2Intent)
}
}
}
class Theme_One : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_theme_one)
val config = PdfActivityConfiguration.Builder(this@Theme_One).build()
val assetFile = Uri.parse("file:///android_asset/theme_one.pdf")
PdfActivity.showDocument(this@Theme_One, assetFile, null, config)
}
}
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.rootsofempathy.recoveryjunior">
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/Theme.RecoveryJunior">
<activity
android:name=".Theme_Ten"
android:exported="true" />
<activity
android:name=".Theme_Nine"
android:exported="true" />
<activity
android:name=".Theme_Eight"
android:exported="true" />
<activity
android:name=".Theme_Seven"
android:exported="true" />
<activity
android:name=".Theme_Six"
android:exported="true" />
<activity
android:name=".Theme_Five"
android:exported="true" />
<activity
android:name=".Theme_Four"
android:exported="true" />
<activity
android:name=".Theme_Three"
android:exported="true" />
<activity
android:name=".Theme_Two"
android:exported="true" />
<activity
android:name=".Theme_One"
android:exported="true" />
<activity
android:name=".MainActivity"
android:exported="true">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.pspdfkit.ui.PdfActivity"
android:theme="@style/RecoveryJunior.PSPDFKitTheme"
android:windowSoftInputMode="adjustNothing" />
<activity
android:name=".getting_ready"
android:theme="@style/Theme.AppCompat.Light.NoActionBar"
android:windowSoftInputMode="adjustNothing" />
<meta-data
android:name="pspdfkit_license_key"
android:value="" />
</application>
</manifest>
If anyone can point me to a clear example on how to make the back button properly re-start the Main Activity buttons I would be grateful.
CodePudding user response:
You can solve this using two ways:
#1 Call finish()
after starting PdfActivity
class Theme_One : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_theme_one)
val config = PdfActivityConfiguration.Builder(this@Theme_One).build()
val assetFile = Uri.parse("file:///android_asset/theme_one.pdf")
PdfActivity.showDocument(this@Theme_One, assetFile, null, config)
finish()
}
}
#2 As per you current code you can directly start your PdfActivity
and skip Theme_one
activity on button click
buttonOne.setOnClickListener {
val config = PdfActivityConfiguration.Builder(this).build()
val assetFile = Uri.parse("file:///android_asset/theme_one.pdf")
PdfActivity.showDocument(this@Theme_One, assetFile, null, config)
}
CodePudding user response:
Your code looks fine.
May the problem is PdfActivity.showDocument(//**//)
remain opened.
Try to implement fragments for your use case.