switch case statement error: case expressions must be constant expression
My switch-case statement works perfectly fine yesterday. But when I run the code earlier this morning eclipse gave me an error underlining the case statements in color red and says: case expressions must be constant expression, it is constant I don't know what happened. Here's my code below:
public void onClick(View src)
{
switch(src.getId()) {
case R.id.playbtn:
checkwificonnection();
break;
case R.id.stopbtn:
Log.d(TAG, "onClick: stopping srvice");
Playbutton.setImageResource(R.drawable.playbtn1);
Playbutton.setVisibility(0); //visible
Stopbutton.setVisibility(4); //invisible
stopService(new Intent(RakistaRadio.this,myservice.class));
clearstatusbar();
timer.cancel();
Title.setText(" ");
Artist.setText(" ");
break;
case R.id.btnmenu:
openOptionsMenu();
break;
}
}
All R.id.int are all underlined in red.
In a regular Android project, constants in the resource R class are declared like this:
public static final int main=0x7f030004;
However, as of ADT 14, in a library project, they will be declared like this:
public static int main=0x7f030004;
In other words, the constants are not final in a library project. Therefore your code would no longer compile.
The solution for this is simple: Convert the switch statement into an if-else statement.
public void onClick(View src)
{
int id = src.getId();
if (id == R.id.playbtn){
checkwificonnection();
} else if (id == R.id.stopbtn){
Log.d(TAG, "onClick: stopping srvice");
Playbutton.setImageResource(R.drawable.playbtn1);
Playbutton.setVisibility(0); //visible
Stopbutton.setVisibility(4); //invisible
stopService(new Intent(RakistaRadio.this,myservice.class));
clearstatusbar();
timer.cancel();
Title.setText(" ");
Artist.setText(" ");
} else if (id == R.id.btnmenu){
openOptionsMenu();
}
}
http://tools.android.com/tips/non-constant-fields
You can quickly convert a switch statement to an if-else statement using the following:
In Eclipse
Move your cursor to the switch keyword and press Ctrl + 1 then select
Convert 'switch' to 'if-else'.
In Android Studio
Move your cursor to the switch keyword and press Alt + Enter then select
Replace 'switch' with 'if'.
取消选中项目Properties中的“Is Library”为我工作。
R.id.*, since ADT 14 are not more declared as final static int so you can not use in switch case construct. You could use if else clause instead.
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