Why creating a new variable and using it when you can use the old variable?

Why do we need to :-

Create a View x.

Then set x = a

Then use a if command on x if you can directly use a.

@Override

public View getView(int position, View convertView, ViewGroup parent) {



    // check if the current view is reused else inflate the view

    View listItemView = convertView;



    if(listItemView == null){

        listItemView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);

    }

Instead , Why can't we do this?

@Override

public View getView(int position, View convertView, ViewGroup parent) {



    if(convertView == null){

        convertView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);

    }

edited Dec 29 '18 at 14:34

Fantômas

32.4k156388

asked Dec 29 '18 at 13:05

Sarvesh Thiruppathi

676

Not recommented to change the original data.

– hesam
Dec 29 '18 at 13:09

add a comment |

Why do we need to :-

Create a View x.

Then set x = a

Then use a if command on x if you can directly use a.

@Override

public View getView(int position, View convertView, ViewGroup parent) {



    // check if the current view is reused else inflate the view

    View listItemView = convertView;



    if(listItemView == null){

        listItemView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);

    }

Instead , Why can't we do this?

@Override

public View getView(int position, View convertView, ViewGroup parent) {



    if(convertView == null){

        convertView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);

    }

edited Dec 29 '18 at 14:34

Fantômas

32.4k156388

asked Dec 29 '18 at 13:05

Sarvesh Thiruppathi

676

Not recommented to change the original data.

– hesam
Dec 29 '18 at 13:09

add a comment |

Why do we need to :-

Create a View x.

Then set x = a

Then use a if command on x if you can directly use a.

@Override

public View getView(int position, View convertView, ViewGroup parent) {



    // check if the current view is reused else inflate the view

    View listItemView = convertView;



    if(listItemView == null){

        listItemView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);

    }

Instead , Why can't we do this?

@Override

public View getView(int position, View convertView, ViewGroup parent) {



    if(convertView == null){

        convertView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);

    }

edited Dec 29 '18 at 14:34

Fantômas

32.4k156388

asked Dec 29 '18 at 13:05

Sarvesh Thiruppathi

676

Why do we need to :-

Create a View x.

Then set x = a

Then use a if command on x if you can directly use a.

@Override

public View getView(int position, View convertView, ViewGroup parent) {



    // check if the current view is reused else inflate the view

    View listItemView = convertView;



    if(listItemView == null){

        listItemView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);

    }

Instead , Why can't we do this?

@Override

public View getView(int position, View convertView, ViewGroup parent) {



    if(convertView == null){

        convertView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);

    }

java android arrays android-arrayadapter

edited Dec 29 '18 at 14:34

Fantômas

32.4k156388

asked Dec 29 '18 at 13:05

Sarvesh Thiruppathi

676

edited Dec 29 '18 at 14:34

Fantômas

32.4k156388

asked Dec 29 '18 at 13:05

Sarvesh Thiruppathi

676

edited Dec 29 '18 at 14:34

Fantômas

32.4k156388

edited Dec 29 '18 at 14:34

Fantômas

32.4k156388

edited Dec 29 '18 at 14:34

Fantômas

32.4k156388

asked Dec 29 '18 at 13:05

Sarvesh Thiruppathi

676

asked Dec 29 '18 at 13:05

Sarvesh Thiruppathi

676

asked Dec 29 '18 at 13:05

Sarvesh Thiruppathi

676

Not recommented to change the original data.

– hesam
Dec 29 '18 at 13:09

add a comment |

Not recommented to change the original data.

– hesam
Dec 29 '18 at 13:09

Not recommented to change the original data.

– hesam
Dec 29 '18 at 13:09

add a comment |

3 Answers
3

active

oldest

votes

First and second examples are valid. Only if first case you are creating an local copy of your class variable. It is useless. Why are developers doing this way? Who knows :)

About inflating. Inflate operations some expensive, cause your adapter items are simular, it is possible to inflate view only once.

answered Dec 29 '18 at 13:16

Dmitro Ivanov

66348

Thanks, Can you elaborate on "Inflate operations some expensive"

– Sarvesh Thiruppathi
Dec 29 '18 at 13:19

See here lucasr.org/2012/04/05/performance-tips-for-androids-listview, so detailed with images.

– Dmitro Ivanov
Dec 29 '18 at 13:24

add a comment |

The second option also works perfectly. I don't know why you think you can't do that.

Just make sure you return convertView after doing other stuffs inside there.

answered Dec 29 '18 at 13:08

Nabin Bhandari

9,32031636

Can you explain a little more , like why the second code is also valid.

– Sarvesh Thiruppathi
Dec 29 '18 at 13:09

It is valid because it works. Can you explain a little more, like why the second code is not valid?

– Nabin Bhandari
Dec 29 '18 at 13:09

I didn't say that the second code is not valid. what I meant was the first code is a common practice I have seen many developers do. My actual question is why create a useless variable which you don't even need.

– Sarvesh Thiruppathi
Dec 29 '18 at 13:11

1

You've asked "Why can't we do this?" and I said you can do that too. There are multiple ways of doing same thing. Both ways are perfectly valid. I have no answer why developers prefer first one. I prefer the second one though.

– Nabin Bhandari
Dec 29 '18 at 13:16

add a comment |

As the develeoper in some cases wanted to assign a value LayoutInflater.from(...).inflate(...), different from the argument convertView, he chose not to overwrite the argument, but to introduce a new variable. It's good style not to modify method arguments.

So, in the case that convertView is null, listItemView gets a value from the LayoutInflater call, to be used further down the method. And the fact that the method was called with a null argument is still visible.

As a more concise alternative, this can be done using Java's ternary operator:

View listItemView = convertView != null ?

        convertView :

        LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);

This way the variable can even be declared final.

answered Dec 29 '18 at 14:39

Ralf Kleberhoff

3,630156

add a comment |

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3 Answers
3

active

oldest

votes

3 Answers
3

active

oldest

votes

First and second examples are valid. Only if first case you are creating an local copy of your class variable. It is useless. Why are developers doing this way? Who knows :)

About inflating. Inflate operations some expensive, cause your adapter items are simular, it is possible to inflate view only once.

answered Dec 29 '18 at 13:16

Dmitro Ivanov

66348

Thanks, Can you elaborate on "Inflate operations some expensive"

– Sarvesh Thiruppathi
Dec 29 '18 at 13:19

See here lucasr.org/2012/04/05/performance-tips-for-androids-listview, so detailed with images.

– Dmitro Ivanov
Dec 29 '18 at 13:24

add a comment |

First and second examples are valid. Only if first case you are creating an local copy of your class variable. It is useless. Why are developers doing this way? Who knows :)

About inflating. Inflate operations some expensive, cause your adapter items are simular, it is possible to inflate view only once.

answered Dec 29 '18 at 13:16

Dmitro Ivanov

66348

Thanks, Can you elaborate on "Inflate operations some expensive"

– Sarvesh Thiruppathi
Dec 29 '18 at 13:19

See here lucasr.org/2012/04/05/performance-tips-for-androids-listview, so detailed with images.

– Dmitro Ivanov
Dec 29 '18 at 13:24

add a comment |

First and second examples are valid. Only if first case you are creating an local copy of your class variable. It is useless. Why are developers doing this way? Who knows :)

About inflating. Inflate operations some expensive, cause your adapter items are simular, it is possible to inflate view only once.

answered Dec 29 '18 at 13:16

Dmitro Ivanov

66348

First and second examples are valid. Only if first case you are creating an local copy of your class variable. It is useless. Why are developers doing this way? Who knows :)

About inflating. Inflate operations some expensive, cause your adapter items are simular, it is possible to inflate view only once.

answered Dec 29 '18 at 13:16

Dmitro Ivanov

66348

answered Dec 29 '18 at 13:16

Dmitro Ivanov

66348

answered Dec 29 '18 at 13:16

Dmitro Ivanov

66348

answered Dec 29 '18 at 13:16

Dmitro Ivanov

66348

Thanks, Can you elaborate on "Inflate operations some expensive"

– Sarvesh Thiruppathi
Dec 29 '18 at 13:19

See here lucasr.org/2012/04/05/performance-tips-for-androids-listview, so detailed with images.

– Dmitro Ivanov
Dec 29 '18 at 13:24

add a comment |

Thanks, Can you elaborate on "Inflate operations some expensive"

– Sarvesh Thiruppathi
Dec 29 '18 at 13:19

See here lucasr.org/2012/04/05/performance-tips-for-androids-listview, so detailed with images.

– Dmitro Ivanov
Dec 29 '18 at 13:24

Thanks, Can you elaborate on "Inflate operations some expensive"

– Sarvesh Thiruppathi
Dec 29 '18 at 13:19

See here lucasr.org/2012/04/05/performance-tips-for-androids-listview, so detailed with images.

– Dmitro Ivanov
Dec 29 '18 at 13:24

add a comment |

The second option also works perfectly. I don't know why you think you can't do that.

Just make sure you return convertView after doing other stuffs inside there.

answered Dec 29 '18 at 13:08

Nabin Bhandari

9,32031636

Can you explain a little more , like why the second code is also valid.

– Sarvesh Thiruppathi
Dec 29 '18 at 13:09

It is valid because it works. Can you explain a little more, like why the second code is not valid?

– Nabin Bhandari
Dec 29 '18 at 13:09

I didn't say that the second code is not valid. what I meant was the first code is a common practice I have seen many developers do. My actual question is why create a useless variable which you don't even need.

– Sarvesh Thiruppathi
Dec 29 '18 at 13:11

1

You've asked "Why can't we do this?" and I said you can do that too. There are multiple ways of doing same thing. Both ways are perfectly valid. I have no answer why developers prefer first one. I prefer the second one though.

– Nabin Bhandari
Dec 29 '18 at 13:16

add a comment |

The second option also works perfectly. I don't know why you think you can't do that.

Just make sure you return convertView after doing other stuffs inside there.

answered Dec 29 '18 at 13:08

Nabin Bhandari

9,32031636

Can you explain a little more , like why the second code is also valid.

– Sarvesh Thiruppathi
Dec 29 '18 at 13:09

It is valid because it works. Can you explain a little more, like why the second code is not valid?

– Nabin Bhandari
Dec 29 '18 at 13:09

I didn't say that the second code is not valid. what I meant was the first code is a common practice I have seen many developers do. My actual question is why create a useless variable which you don't even need.

– Sarvesh Thiruppathi
Dec 29 '18 at 13:11

1

You've asked "Why can't we do this?" and I said you can do that too. There are multiple ways of doing same thing. Both ways are perfectly valid. I have no answer why developers prefer first one. I prefer the second one though.

– Nabin Bhandari
Dec 29 '18 at 13:16

add a comment |

The second option also works perfectly. I don't know why you think you can't do that.

Just make sure you return convertView after doing other stuffs inside there.

answered Dec 29 '18 at 13:08

Nabin Bhandari

9,32031636

The second option also works perfectly. I don't know why you think you can't do that.

Just make sure you return convertView after doing other stuffs inside there.

answered Dec 29 '18 at 13:08

Nabin Bhandari

9,32031636

answered Dec 29 '18 at 13:08

Nabin Bhandari

9,32031636

answered Dec 29 '18 at 13:08

Nabin Bhandari

9,32031636

answered Dec 29 '18 at 13:08

Nabin Bhandari

9,32031636

Can you explain a little more , like why the second code is also valid.

– Sarvesh Thiruppathi
Dec 29 '18 at 13:09

It is valid because it works. Can you explain a little more, like why the second code is not valid?

– Nabin Bhandari
Dec 29 '18 at 13:09

I didn't say that the second code is not valid. what I meant was the first code is a common practice I have seen many developers do. My actual question is why create a useless variable which you don't even need.

– Sarvesh Thiruppathi
Dec 29 '18 at 13:11

1

You've asked "Why can't we do this?" and I said you can do that too. There are multiple ways of doing same thing. Both ways are perfectly valid. I have no answer why developers prefer first one. I prefer the second one though.

– Nabin Bhandari
Dec 29 '18 at 13:16

add a comment |

Can you explain a little more , like why the second code is also valid.

– Sarvesh Thiruppathi
Dec 29 '18 at 13:09

It is valid because it works. Can you explain a little more, like why the second code is not valid?

– Nabin Bhandari
Dec 29 '18 at 13:09

I didn't say that the second code is not valid. what I meant was the first code is a common practice I have seen many developers do. My actual question is why create a useless variable which you don't even need.

– Sarvesh Thiruppathi
Dec 29 '18 at 13:11

1

You've asked "Why can't we do this?" and I said you can do that too. There are multiple ways of doing same thing. Both ways are perfectly valid. I have no answer why developers prefer first one. I prefer the second one though.

– Nabin Bhandari
Dec 29 '18 at 13:16

Can you explain a little more , like why the second code is also valid.

– Sarvesh Thiruppathi
Dec 29 '18 at 13:09

It is valid because it works. Can you explain a little more, like why the second code is not valid?

– Nabin Bhandari
Dec 29 '18 at 13:09

I didn't say that the second code is not valid. what I meant was the first code is a common practice I have seen many developers do. My actual question is why create a useless variable which you don't even need.

– Sarvesh Thiruppathi
Dec 29 '18 at 13:11

You've asked "Why can't we do this?" and I said you can do that too. There are multiple ways of doing same thing. Both ways are perfectly valid. I have no answer why developers prefer first one. I prefer the second one though.

– Nabin Bhandari
Dec 29 '18 at 13:16

add a comment |

As a more concise alternative, this can be done using Java's ternary operator:

View listItemView = convertView != null ?

        convertView :

        LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);

This way the variable can even be declared final.

answered Dec 29 '18 at 14:39

Ralf Kleberhoff

3,630156

add a comment |

As a more concise alternative, this can be done using Java's ternary operator:

View listItemView = convertView != null ?

        convertView :

        LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);

This way the variable can even be declared final.

answered Dec 29 '18 at 14:39

Ralf Kleberhoff

3,630156

add a comment |

As a more concise alternative, this can be done using Java's ternary operator:

View listItemView = convertView != null ?

        convertView :

        LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);

This way the variable can even be declared final.

answered Dec 29 '18 at 14:39

Ralf Kleberhoff

3,630156

As a more concise alternative, this can be done using Java's ternary operator:

View listItemView = convertView != null ?

        convertView :

        LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);

This way the variable can even be declared final.

answered Dec 29 '18 at 14:39

Ralf Kleberhoff

3,630156

answered Dec 29 '18 at 14:39

Ralf Kleberhoff

3,630156

answered Dec 29 '18 at 14:39

Ralf Kleberhoff

3,630156

answered Dec 29 '18 at 14:39

Ralf Kleberhoff

3,630156

add a comment |

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