R cannot be resolved to a variable
Check your xml files in Eclipse Graphical Editor and fix problems.
Check project setup, right click on project, select properties, Java build path and
select correct Android version etc.
Right click on project, Android Tools, Fix Project Properties
Menu Eclipse select Project ->Clean.

Check project setup, right click on project, select properties, Java build path and
select correct Android version etc.

Right click on project, Android Tools, Fix Project Properties
Menu Eclipse select Project ->Clean.
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Další témata ....(Topics)
public class MainActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
LinearLayout layout = (LinearLayout) findViewById(R.id.layout);
TextView textView = new TextView(this);
textView.setText("Text View ");
LinearLayout.LayoutParams p = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.FILL_PARENT,
LinearLayout.LayoutParams.WRAP_CONTENT
);
layout.addView(textView, p);
Button buttonView = new Button(this);
buttonView.setText("Button");
buttonView.setOnClickListener(mThisButtonListener);
layout.addView(buttonView, p);
}
private OnClickListener mThisButtonListener = new OnClickListener() {
public void onClick(View v) {
Toast.makeText(MainActivity.this, "Hello !",
Toast.LENGTH_LONG).show();
}
};
}
Issue: After after renaming package this problem occurred "R cannot be resolved to a variable".
Solution: Try Clean your project Project » Clean » Clean projects selected below » select your project and click OK.
Try to delete the invalid code and type it again:
Solution: Try Clean your project Project » Clean » Clean projects selected below » select your project and click OK.
Try to delete the invalid code and type it again:
LinearLayout layout = (LinearLayout) findViewById(R.id.layout); // delete R.id.layout
LinearLayout layout = (LinearLayout) findViewById();
LinearLayout layout = (LinearLayout) findViewById(R.id.layout); // re-write this code R.id.layout
How include layout defined in other xml file into another xml file example:
res/layout/my_layout.xml into
main.xml
res/layout/my_layout.xml into
main.xml
<include layout="@layout/my_layout" android:id="@+id/idMyLayout" />
You can use for, do while, while cycle for example:
public void myFunction(){
for (int i = 0; i < 1; i++) {
// some code
int c = 10;
if(c==10)
break; // goto stop; in C++
} // end of for
// stop: // break moved process to end of for
// next code
}
Android development
long is 64 bit signed type and used when int is not large enough to hold the value.
long je celé číslo 64 bitů -9223372036854775808 +9223372036854775807 a používá se tam, kde typ int není schopen pojmout takovou hodnotu čísla.
long is 64 bit signed type and used when int is not large enough to hold the value.
long je celé číslo 64 bitů -9223372036854775808 +9223372036854775807 a používá se tam, kde typ int není schopen pojmout takovou hodnotu čísla.
// declaration and assignment of value type long
long n = 22337203685477580L;
// print formated value
System.out.printf("The value of x is %d%n", n); // 22337203685477580
System.out.format("%+,8d%n%n", n); // +22 337 203 685 477 580
// declaring more variables in single statement
long lo1 = 12L, lo2 = 56, lo3 = 1455555555589L;
// long range of value
System.out.println(Long.MAX_VALUE); // 9223372036854775807
System.out.println(Long.MIN_VALUE); // -9223372036854775808
// check if a string is a valid number in Java example
// convert string to long Java example
String sLong = "1288888888888888";
long longParse = Long.parseLong(sLong);
// convert strings to numbers
long longFromString = (Long.valueOf(sLong)).longValue();
// long to string in Java example code
Long longObj = new Long(229999999999L);
String str = longObj.toString();
// else
Long longS = 888888888888L;
String strLong = longS.toString();
// compare two long variables
Long longComp1 = 5555L;
if (longComp1.equals(55555555L))
System.out.print("true");
// compares the two specified long values in Java example
int i = longS.compareTo(444444L); // -1 first < second
// 0 first == second
// 1 first > second
System.out.print(i);
Editace: 2014-02-15 20:14:31
Počet článků v kategorii: 396
Url:r-cannot-be-resolved-to-a-variable