Here is the full source code to create an AlertDialog and add Buttons using the setPositiveButton and setNegativeButton methods and how to send a click on those Buttons back to the Activity by implementing an interface and making our MainActivity a Listener
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 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"
tools:context="com.example.application.exampleapplication.MainActivity">
<TextView
android:id="@+id/counter_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="0"
android:textSize="60sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="8dp"
android:layout_marginTop="0dp"
android:layout_marginRight="8dp"
android:text="open dialog"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@id/counter_text" />
</android.support.constraint.ConstraintLayout>
ExampleDialog.java
package com.example.application.exampleapplication;
import android.app.Dialog;
import android.content.Context;
import android.content.DialogInterface;
import android.os.Bundle;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatDialogFragment;
public class ExampleDialog extends AppCompatDialogFragment {
private ExampleDialogListener listener;
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
builder.setTitle("Attention!")
.setMessage("Do you want to increase the counter by 1?")
.setNegativeButton("cancel", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
}
})
.setPositiveButton("yes", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialogInterface, int i) {
listener.onYesClicked();
}
});
return builder.create();
}
public interface ExampleDialogListener {
void onYesClicked();
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
try {
listener = (ExampleDialogListener) context;
} catch (ClassCastException e) {
throw new ClassCastException(context.toString()
+ "must implement ExampleDialogListener");
}
}
}
MainActivity.java
package com.example.application.exampleapplication;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity implements ExampleDialog.ExampleDialogListener {
private TextView counterText;
private Button button;
private int counter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
counterText = (TextView) findViewById(R.id.counter_text);
button = (Button) findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
openDialog();
}
});
}
public void openDialog() {
ExampleDialog dialog = new ExampleDialog();
dialog.show(getSupportFragmentManager(), "example dialog");
}
@Override
public void onYesClicked() {
counter++;
counterText.setText("" + counter);
}
}