I come from the iOS world and just started with Android. I followed a java training so I know how to create a method, but I don't get the action one.
What I would like to do is to create a method action from a button and I can't find anywhere how to do that (obviously looking in the wrong place). When I click on button 1, I want to create a method with inside only a=1 and when I click on button 2, I want a=2 (then I can decide what to do when a is 1 or 2).
I created my buttons in Acitivity_main.xml and gave a method name in OnClick, but that's as far as I went.
It seems to be so basic to do when I compare with iOS that I don't understand why I can't find how to do it.
Would a nice soul point me in the right direction for creating an action please?
You have three options:
common in 1,2) You need to assign an id to each of your buttons in the layout XML file
<Button android:id="@+id/my_button1"
..........
/>
<Button android:id="@+id/my_button2"
..........
/>
1) In the activity's onCreate() method after setContentView() you need to set a new OnClickListener for each button.
public class MyActivity extends Activity {
int a;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button myButton1 = (Button) findViewById(R.id.my_button1);
Button myButton2 = (Button) findViewById(R.id.my_button2);
myButton1.setOnClickListener( new OnClickListener() {
@Override
public void onClick(View v) {
// Do what you want here
a = 1;
}
});
myButton2.setOnClickListener( new OnClickListener() {
@Override
public void onClick(View v) {
// Do what you want here
a = 2;
}
});
}
2) As you see in the first approach, we need to make a new Object from the OnClickListener for each button. We can mix all that into one OnClickListener for performance and readability reasons.
public class MyActivity extends Activity implements View.OnClickListener {
int a;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button myButton1 = (Button) findViewById(R.id.my_button1);
myButton1.setOnClickListener(this);
Button myButton2 = (Button) findViewById(R.id.my_button2);
myButton2.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.my_button_1:
a = 1;
break;
case R.id.my_button_2:
a = 2;
break;
}
}
...
}
3) You don't need to assign an id for this option you just need to assign the method name in the XML and then implement the same method in the activity with the exact same name but it must take a View object as an argument.
<Button
...
android:onClick="button1Click" />
<Button
...
android:onClick="button2Click" />
and then in your activity just write the methods.
public class MyActivity extends Activity implements View.OnClickListener {
int a;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void button1Click(View v) {
a = 1;
}
public void button2Click(View v) {
a = 2;
}
}
That's all your options. I personally prefer number 2.
You've two options to handle the buttons, from the documentation:
a) Declare and define you method in you java file
int a = 0;
final Button button = (Button) findViewById(R.id.button_id);
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
a = 1;
}
});
b) or define you method in you xml layout:
<Button
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:text="@string/self_destruct"
android:onClick="selfDestruct" />
And then in you java file:
int a = 0;
public void selfDestruct(View view) {
a = 1;
}
First assign the button in yours xml file like below:-
<Button android:id="@+id/button1"
..........
/>
<Button android:id="@+id/button2"
..........
/>
After finding there ids from xml than set the OnclickListener on it like below and do not forget to implement the OnClickListener listener on yours class like public class CLASSNAME extends Activity implements OnClickListener
button1 .setOnClickListener(CLASSNAME.this);
button2.setOnClickListener(CLASSNAME.this);
Than after implements the onclickListener than it will provide you a overrided method like onclick(View v)
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.button1 : //Here i assumes that button1 is the name of button in yours xml which you declare button1
// do something on button1 click
break;
case R.id.button2 :////Here i assumes that button2 is the name of button in yours xml which you declare button2
// do something on button2 click
break;
}
}
There are two ways to perform action on a Button click
the first approach is to set an android:OnClick = "methodName" in the layout (xml) file in the Button code and use that method in the java code to access that Button like
public void methodName(View v) {
// Do what you want to perform on Button click
}
the second way to perform some thing behind a button is to access that button in java code and do what you want to do like
Button button = findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// Do what you want to perform on that button click
}
});
