I want to return to the previous screen with kotlin and java!

Introduction ...

This article was written in 5 previous articles,

** 6th day of article posting every day for 7 days **

It has become

I'll put the code to use below, but see the article five before for the detailed features of this app!

--java version: https://github.com/sato-na/guruwake_java

--kotlin version: https://github.com/sato-na/guruwake_kotlin

↓ This is the main subject of this article ↓

To return to the previous screen in each language ...

• This is a method to return to the previous screen from the back button on the toolbar.

How to implement the toolbar

--For java

Toolbar variable name= findViewById(R.id.Toolbar id);
setSupportActionBar(variable);

Example)

WhoActiity.java

Toolbar whoTb = findViewById(R.id.who_tb);  //30th line
setSupportActionBar(whoTb);

--For kotlin

setSupportActionBar(Toolbar id)

Example)

WhoActivity.kt

setSupportActionBar(who_tb)  //21st line

java needs to create a ToolBar type variable, but kotlin doesn't need to

How to go back with the back button on the toolbar

--For java

(In the onCreate function)

getSupportActionBar().setDisplayShowHomeEnabled(true);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);

(Outside the onCreate function)

@Override
public boolean onSupportNavigateUp() {
    finish();
    return super.onSupportNavigateUp();
}

Example) (In the onCreate function)

WhoActivity.java

getSupportActionBar().setDisplayShowHomeEnabled(true);  //32nd line
getSupportActionBar().setDisplayHomeAsUpEnabled(true);

(Outside the onCreate function)

WhoActivity.java

@Override  //Line 69
public boolean onSupportNavigateUp() {
    finish();
    return super.onSupportNavigateUp();
}

--For kotlin

supportActionBar?.let {  //Line 22
    it.setDisplayHomeAsUpEnabled(true)
    it.setHomeButtonEnabled(true)
} ?: IllegalAccessException("Toolbar cannot be null")

AndroidManifest.xml

<activity
    android:name=".WhoActivity"
    android:parentActivityName=".MainActivity" />  //← Add here

Example)

WhoActivity.kt

supportActionBar?.let {  //Line 22
    it.setDisplayHomeAsUpEnabled(true)
    it.setHomeButtonEnabled(true)
} ?: IllegalAccessException("Toolbar cannot be null")

AndroidManifest.xml

<activity  //20th line
    android:name=".WhoActivity"
    android:parentActivityName=".MainActivity" />

java needs to define code and new functions, kotlin needs to edit code and AndroidManifest.xml

Finally…

This time I used the toolbar with java and kotlin to return to the previous screen. I felt that both languages required more complex code than screen transitions.

I will post an article tomorrow, so please keep an eye on me.