Evaluating String indexof

[Steve Dyke]

I have the following code why if value is "" does indexof get evaluated to 0:


spoc exclusion list = ('S070','S100','S110','S120','S130','S150','S200')

private String spocno = "";//item class property default value
dft.getSpocexclusionlist().indexOf(item.getSpocno()) > -1?100:0;

[Paul Clapham]

It's because the first place in the string "S070" which matches a zero-length string is at the beginning, i.e. position zero. If that's a little too obscure for you, then have a look at the API documentation for the startsWith() method of String, which says

"Returns true if the character sequence represented by the argument is a prefix of the substring of this object starting at index toffset; false otherwise."

And if you look at it that way, then "" is indeed the first zero characters of "S070".

[Rob Spoor]

Is it indexOf that gets evaluated to 0, or the result of that last line? Because the last line says that if indexOf returns anything larger than -1, 100 should be used and otherwise 0. In other words, if indexOf returns -1 then 0 must be used.

[Steve Dyke]

 

Rob Spoor wrote:Is it indexOf that gets evaluated to 0, or the result of that last line? Because the last line says that if indexOf returns anything larger than -1, 100 should be used and otherwise 0. In other words, if indexOf returns -1 then 0 must be used.

No it always returns 100 even when item.getSpocno() == "".

The only I could get it to work was to replace the item.spoc = "" with item.spoc = "N/A" in the item class property. This is the item class:

public class Item {
...
private String spocno = "N/A";
...
public Item(){
}
public Item(ResultSet rs){
...
try{this.spocno = rs.getString("uuca").trim().equals("")?"N/A":rs.getString("uuca").trim();}catch(Exception e){this.spocno = "N/A";}
...
}
}
public String getSpocno() {
return spocno;
}
public void setSpocno(String spocno) {
this.spocno = spocno;
}