What error it could be

What error it could be

like you could see here in code under that there is no syntax error but
each and every line seems right but when this code is being used in my
Application the " if " statement not works...... its not matching the
string with already existing string array. if i remove that if statements
it works fine for all the iteration. (i've checked by putting same
entities but it's still not working)
I don't want solution i want to know the reason....??? Thanks
NOTE:
s1 ' is a string array (not empty)
searchentry ' is a string (not empty)
Code:
public void searchCapability(){
boolean NotFound=true;
///////////////// Linear Folder Search /////////////
for(int i=0; i<s1.length; i++){
if(searchentry==s1[i]){ // code under this if is not working as
if is true or false
l1.setSelectedIndex(i);
NotFound=false;
}
}
/////////////////// Linear File search /////////////
for(int i2=0; i2<s2.length; i2++){
// code under this if is not working as if is true or false
if((searchentry+".xls")==s2[i2]){
l2.setSelectedIndex(i2);
t1.setText(s3);
NotFound=false;
}
}
if(NotFound==true){
JOptionPane.showMessageDialog(null, "Entry Not Found :)",
"Error", JOptionPane.INFORMATION_MESSAGE);
}
}