I have a list of Clickable TextViews that are relatively doing the same thing. You click on it and it goes to that activity. Settings goes to the settings activity. About to the about and so forth. Is there an easier way to declare and set up these clickable TextViews besides this repetitious code?
TextView create,
edit,
settings,
about;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_navigation);
create = (TextView) findViewById(R.id.create);
create.setTextColor(Color.parseColor("#000000"));
edit = (TextView) findViewById(R.id.edit);
edit.setTextColor(Color.parseColor("#000000"));
settings = (TextView) findViewById(R.id.settings);
settings.setTextColor(Color.parseColor("#000000"));
about = (TextView) findViewById(R.id.about);
about.setTextColor(Color.parseColor("#000000"));
create.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v) {
}
});
edit.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
}
});
settings.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
}
});
about.setOnClickListener(new View.OnClickListener(){
#Override
public void onClick(View v){
}
});
If you have a small set of items you can take following approach:
public class MyActivity extends Activity implements AdapterView.OnItemClickListener {
private ArrayAdapter<Item> mAdapter;
private static enum Item {Create,Edit,Settings,About}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//-- can set up from external layout also--
ListView list = new ListView(this);
setContentView(list);
list.setOnItemClickListener(this);
mAdapter = new ArrayAdapter<Item>(this,android.R.layout.simple_list_item_1,Item.values());
list.setAdapter(mAdapter);
}
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
switch (mAdapter.getItem(i)){
case Create:
//--do stuff--
break;
case Edit:
//--do stuff--
break;
case Settings:
//--do stuff--
break;
case About:
//--do stuff--
break;
}
}
}
You can implement the View.OnClickListener .
public class YOURACTIVITY extends Activity implements OnClickListener
And in the onCreate()-
yourTextview.setOnClickListener(this);
and then
#Override
public void onClick(View v) {
// Based on the view , set the action
}
Related
I'm super new in Java! Pardon for this question although there are similar ones but I'm completely clueless on fixing my problem.
I'm trying to set an OnClickListener for each ImageButton to open a new activity.
The first ImageButton works but not for the subsequent ones, it is unclickable in AVD.
Would greatly appreciate some help on it!
public class CharacterSelect extends AppCompatActivity {
ImageButton arrowbtnright;
ImageButton contchibtn;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_character_select);
arrowbtnright = (ImageButton) findViewById(R.id.arrowbtnright);
contchibtn = (ImageButton) findViewById(R.id.contchibtn);
arrowbtnright.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(CharacterSelect.this, CharacterSelect2.class));
contchibtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(CharacterSelect.this, MiniChallenge1.class));
}
});
}
});
}
You are currently adding the listener of the second button, from inside the listener of the first button, this is probably not what you want to do .
Try putting both at the same level, i.e :
arrowbtnright.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(final View v) {
startActivity(new Intent(CharacterSelect.this, CharacterSelect2.class));
}
});
contchibtn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(final View v) {
startActivity(new Intent(CharacterSelect.this, MiniChallenge1.class));
}
});
I want to use the button for different calls in the different classes. However, when I declare and try to call the Button click method in the Activity class, it throws a null exception. In my Class I want to do this:
public class CustomFeedListViewAdapter extends BaseAdapter {
holder.feedUpVoteButton = (Button) view.findViewById(R.id.feedUpVoteButton);
holder.feedUpVoteButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//do stuff
}
});
private class ViewHolder {
Button feedUpVoteButton;
}
And in my main activity I want to do this:
public class Feed extends AppCompatActivity {
Button upVoteButton;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_feed);
upVoteButton = (Button) findViewById(R.id.feedUpVoteButton);
feedUpVoteButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//do stuff
}
});
}
}
You are getting NullPointerException because you are trying to access feedUpVoteButton which is present in the item layout used in CustomFeedListViewAdapter and not in the layout used by Feed activity.
Do you want to have access to the ClickListener whenever you create an adapter of type CustomFeedListViewAdapter? If yes then do this...
Your Activity class
public class Feed extends AppCompatActivity {
CustomFeedListViewAdapter adapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_feed);
adapter = new CustomFeedListViewAdapter( new OnClickListener() {
#Override
public void onClick(View v) {
// Handle click here
}
});
}
}
And your custom adapter class
public class CustomFeedListViewAdapter extends BaseAdapter {
View.OnClickListener clickListener;
// Constructor
public CustomFeedListViewAdapter(View.OnClickListener listener) {
clickListener = listener;
}
#Override
void getView(){
holder.feedUpVoteButton = (Button) view.findViewById(R.id.feedUpVoteButton);
holder.feedUpVoteButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//do stuff
}
});
}
}
This way you can set a different listener for each instance of the adapter you create.
I've just started to learn Java and I've been stumped on adding the code for a second button in an activity. I apologize for my (possible dumb question) and any wrong terminology.
Here is the MainActivity Java code:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btnGo = (Button) findViewById(R.id.btnGo);
btnGo.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(MainActivity.this, GoActivity.class));
}
});
}
}
How can I add to this code for btnEscape to go to EscapeActivity?
You just have to do exacly the same thing you do with btnGo - this is find your button by id, and then set clickListener to it. It could looks like that:
Button btnEscape = (Button) findViewById(R.id.btnEscape);
btnEscape.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(MainActivity.this, EscapeActivity.class));
}
});
The optimised way to do that is implement your class with View.OnClickListener and override the method onClick and inside it use switch cases to switch between views and apply on clicks like this:
public class SampleActivity extends AppCompatActivity implements View.OnClickListener{
Button btnGo,btnEscape;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnGo = (Button) findViewById(R.id.btnGo);
btnEscape= (Button) findViewById(R.id.btnEscape);
btnGo.setOnClickListener(this);
btnEscape.setOnClickListener(this);
}
#Override
public void onClick(View v) {
switch (v.getId()){
case R.id.btnGo:
startActivity(new Intent(MainActivity.this, GoActivity.class));
break;
case R.id.btnEscape:
startActivity(new Intent(MainActivity.this, EscapeActivity.class));
break;
default:
break;
}
}
}
In code, what the two comments by Shiram and Nik above are saying is to add the block below that begins Button btnEscape... after Button btnGo.setOnclick's block.
#Override
protected void onCreate(Bundle savedInstanceState) {
...
Button btnGo = (Button) findViewById(R.id.btnGo);
...
Button btnEscape = (Button) findViewById(R.id.<<name of button in xml>>);
btnEscape.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
... whatever ... }
});
}
In short, the following is a really good pattern to have at your fingertips:
Button btn___ = (Button) findViewById(R.id.<<name of button in xml>>);
btn___.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
... whatever ... }
});
I am a beginner at Java and as not as familiar with its syntax as compared to C.
Specifically I have the follow code; there are 2 TextViews view1, view2, and I make the same Toast message pop up on clicking either TextViews
public class MainActivity extends ActionBarActivity {
private TextView view1, view2;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
view1 = (TextView)findViewById(R.id.item_1a);
view1.setOnClickListener(new OnClickListener()
{
#Override
public void onClick(View v) {
Toast.makeText(v.getContext(),"button clicked",Toast.LENGTH_SHORT).show();
}
});
view2 = (TextView)findViewById(R.id.item_1b);
view2.setOnClickListener(new OnClickListener(){
#Override
public void onClick(View v) {
Toast.makeText(v.getContext(),"button clicked",Toast.LENGTH_SHORT).show();
}
});
}
}
I realised that if there are 100 TextViews, it will be inefficient if i keep overriding onClick 100 times.
As such, is there a way to override onClick just once, and let all instances of setOnClickListener to refer back to the same onClick?
Thanks!
Define a class which implements OnClickListener along the lines of
class MyClickListener implements OnClickListener{
#Override
public void onClick(View v) {
Toast.makeText(v.getContext(),"button clicked",Toast.LENGTH_SHORT).show();
}
}
and then you can use the same class everywhere. For example:
// say you have 100 TextViews
for (int i = 0; i < views.length; i++)
views[i].setOnClickListener(new MyClickListener());
If it is the same message you can do it this way:
public class MainActivity extends ActionBarActivity {
private TextView view1, view2;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
OnClickListener listener = new OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(v.getContext(), "button clicked", Toast.LENGTH_SHORT).show();
}
};
view1 = (TextView) findViewById(R.id.item_1a);
view1.setOnClickListener(listener);
view2 = (TextView) findViewById(R.id.item_1b);
view2.setOnClickListener(listener);
}
}
Sure. What you are implementing are called "anonymous inner types".
OnClickListener listener = new OnClickListener()
{
#Override
public void onClick(View v) {
Toast.makeText(v.getContext(),"button clicked",Toast.LENGTH_SHORT).show();
}
};
view1 = (TextView)findViewById(R.id.item_1a);
view1.setOnClickListener(listener);
view2 = (TextView)findViewById(R.id.item_2a);
view2.setOnClickListener(listener);
Or you can create a subclass of the OnClickListener class, like #webuster answered.
You can probably affect your listener to a variable and assign it to views :
OnClickListener listener = new OnClickListener(){
#Override
public void onClick(View v) {
Toast.makeText(v.getContext(),"button clicked",Toast.LENGTH_SHORT).show();
}
};
view1.setOnClickListener(listener);
view2.setOnClickListener(listener);
You have to set the onclicklistener on each View but there is a cleaner way of doing so.
Put this in the Activity code:
public void myOnclickListener(View v) {
Toast.makeText(v.getContext(),"button clicked",Toast.LENGTH_SHORT).show();
}
Then set the click listener in your xml:
<TextView
android:id="#+id/mytext"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="myOnclickListener"
/>
Well, Suppose there is an Activity called MainActivity and there are two layouts called layout1 and layout2 both have few buttons. By default MainActivity layout is layout1 like following:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.layout1);
Now what I did actually is by clicking a button in layout1 the second layout is set like following:
someBtn1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
setContentView(R.layout.layout2);
}
});
There are another button in layout2 to return back to layout1 like following:
someBtn2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
setContentView(R.layout.layout1);
}
});
Problem is when I returned back to layout1 then OnClickListener of someBtn1 is not working. It seems I need to set OnClickListener again for someBtn1 of layout1.
How I can write code to make them work perfectly with best practices ?
The best practice is to use fragments instead of change the content view.
In your code, setContentView with layouts recreate (inflate) all your views every time, so the call setContentView(R.layout.layout1) in someBtn2 click listener will create a new button without the associated listener.
If you don't want to use fragments you can do this:
private View view1, view2;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
view1 = getLayoutInflater().inflate(R.layout.layout1, null);
view2 = getLayoutInflater().inflate(R.layout.layout2, null);
setContentView(view1);
The listeners will be:
someBtn1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
setContentView(view2);
}
});
someBtn2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
setContentView(view1);
}
});
If you just want to play around with your current code, a solution for your problem is that the listeners must be redeclared when the layout changes, as follows:
someBtn1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
setContentView(R.layout.layout2);
someBtn2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
setContentView(R.layout.layout1);
}
});
}
});
someBtn2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
setContentView(R.layout.layout1);
someBtn1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
setContentView(R.layout.layout2);
}
});
}
});
An alternative to avoid declaring the listeners twice is to declare two methods to handle the layout changes and use the onClick property of the button in each of the layouts, for example:
public void setLayout1(View view) {
setContentView(R.layout.layout1);
}
public void setLayout2(View view) {
setContentView(R.layout.layout2);
}
In layout1.xml:
<Button
android:id="#+id/someBtn1"
android:onClick="setLayout2"/>
In layout2.xml:
<Button
android:id="#+id/someBtn2"
android:onClick="setLayout1"/>
However, if you want to follow best practices, the best practice is not to mix layouts in the same activity, but instead declare two different activities (each one with its own layout) and call one activity or the other depending on the button that was clicked. Suppose that you are in Activity1 and want to call Activity2, then go back to Activity1:
In Activity1.java:
someBtn1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
startActivity(new Intent(this, Activity2.class));
}
});
In Activity2.java:
someBtn2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
finish();
}
});
One way of doing this is loading both views in onCreate(...), and then switching between them by making the one you don't want invisible. Something like the following:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
inflater = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
LayoutParams default_layout_params = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
View view1 = inflater.inflate(R.layout.layout1, null);
addContentView(view1, default_layout_params);
View view2 = inflater.inflate(R.layout.layout2, null);
addContentView(view2, default_layout_params);
view2.setVisibility(View.INVISIBLE);
view1.setVisibility(View.VISIBLE);
view1.bringToFront();
At the time you callback layout1, data must be set again.
You could merge both layouts in one and then use ViewFlipper to switch between them.
When you are seting layout2, you should also set up OnClickListener to someBtn1 and vice versa, I'd suggest something like this. But as in prevoius answer, in general you should avoid mixing layouts in such manner.
public class MainActivity extends Activity {
private final View.OnClickListener setLayout1Listener = new View.OnClickListener() {
#Override
public void onClick(View view) {
setContentView(R.layout.layout2);
((Button)findViewById(R.id.Btn2Id)).setOnClickListener(setLayout2Listener);
//do other stuff
}
};
private final View.OnClickListener setLayout2Listener = new View.OnClickListener() {
#Override
public void onClick(View view) {
setContentView(R.layout.layout1);
((Button)findViewById(R.id.Btn1Id)).setOnClickListener(setLayout1Listener);
//do other stuff
}
};
#Override
public void onCreate(final Bundle savedInstance) {
super.onCreate(savedInstanceState);
setContentView(R.layout.layout1);
((Button)findViewById(R.id.Btn1Id)).setOnClickListener(setLayout1Listener);
//do other stuff
}
}