Question

i have a code where i create a .xlsm file, in determined part, the code does a mysql select and set the resulset in a array, and i have to check this array if are empty or not. But, or, it returns true everytime, or, it returns false everytime. This select for example, there is a value in 296th index, and other in 322th index, but, this time, the empty boolean it is returning me true, where, were to return false, 'cause there is value in the array. i tried some things, but, i got nothing solution.

What am i doing wrong ?

This my java code:

ResultSet check_name = connect.createStatement().executeQuery("select `name` from `company`"); 
ArrayList<String> names = new ArrayList<String>(); boolean empty = true;

while(check_name.next()){ 
 names.add(name.getString("name")); 
} 

for(int l = 0; l < names.size(); l++){
 if(names.get(l).contains("[0-9a-zA-Z]+")){
  empty = false; break; 
 } 
}

if(empty == true){
 cell = row.createCell(26);
 cell.setCellValue("it's empty");
}else{
 cell = row.createCell(26);
 cell.setCellValue("it's not empty");
}

Answer 1

You should use trim() and isEmpty() methods of String class.

for(int l = 0; l < names.size(); l++){
 if(names.get(l)!=null && !(names.get(l).trim().isEmpty())){
  empty = false; break; 
 } 
}

Answer 2

This statement is the culprit:

if(names.get(l).contains("[0-9a-zA-Z]+"))

I think you were trying to do some kind of regex, but it simply checks if the string contains this value: "[0-9a-zA-Z]+"

It must be false in your case always and hence your empty flag is always true!

Answer 3

Contains is looking for a char sequence, not a regex. So, it is not matching what you expect.

You should use isEmpty() instead. if(!names.get(l).isEmpty())

Answer 4

        for(int l = 0; l < names.size(); l++){
    String name = name.get(l);
if(name.equals("")){
Log.d("TEXT ?","Doesn't CONTAIN TEXT");
}else{
Log.d("TEXT ?","CONTAIN TEXT");
}

  }

Why are you going in such mess when you simply check if the String contains null value or not . Let me know if this work , Mark it as answered if this works .

Java - How check if array there is value or not

4 个答案: