In a project there will be lots of pages(activities) and user will be able to switch between these pages (activities). So when user press the corresponding button that opens page_2 from page_1, I need to create a new Activity. However, if user comes back to page_1 and try to open the page_2 again, there will be a new Activity created again, instead of opening the previously created activity ( I want user to see the page_2 as he/she left it without anychanges). So I want to put something like
if(SecondActivity==null)
{
//Create new activity
}
start(new_activity);
Here is the corresponding code ( I couldn't implement onClickListener because I couldn't disable it in onPause() method... so I used onClick from xml)
public class MainActivity extends Activity {
private View.OnClickListener openSecondPage = new View.OnClickListener() {
@Override
public void onClick(View v) {
Button button_newPage = findViewById(R.id.button_newpage);
button_newPage.setText("Clicked");
Intent secondPage = new Intent(getApplicationContext(), SecondActivity.class );
startActivity(secondPage);
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void onResume(){
super.onResume();
//Button button_newPage = findViewById(R.id.button_newpage);
// button_newPage.setOnClickListener(openSecondPage);
}
public void onPause(){
super.onPause();
//Destroy the on click listener
Button button_newPage = findViewById(R.id.button_newpage);
// button_newPage.setOnClickListener(null);
}
public void openSecondPage(View v)
{
Intent secondPage = new Intent(getApplicationContext(), SecondActivity.class );
startActivity(secondPage);
}
}
Edit: Here is the new code with Flags:
MainActivity.java code:
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void onResume(){
super.onResume();
}
public void onPause(){
super.onPause();
}
public void openSecondPage(View v)
{
Intent secondPage = new Intent(getApplicationContext(), SecondActivity.class );
secondPage.setFlags(Intent.FLAG_ACTIVITY_BROUGHT_TO_FRONT);
startActivity(secondPage);
}
}
SecondActivity.java code:
public class SecondActivity extends Activity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.secondactivity);
}
protected void onResume()
{
super.onResume();
}
public void goBack(View v)
{
}
public void goMainPage(View v)
{
Intent mainPage = new Intent(getApplicationContext(),MainActivity.class);
mainPage.setFlags(Intent.FLAG_ACTIVITY_BROUGHT_TO_FRONT);
startActivity(mainPage);
}
}
