Bug on Printstream. Only last statement ist writing

Question

I have got following Problem. The string variable prints on the txt file

```
 1 3 1.
```

Actually, it must outputs

```
1 1 1 
1 2 1
1 3 1
```

I don't know, where the error is in the Code. It seems to be that the code is overwriting everytime, and the last statement was overwrites. Can anyone helps me

public class RankingExportTest {
private static final String LINE_SEPARATOR = "\r\n";
Set<String> exportGraph(DirectedUnweightedGraph<CommonNode, CommonEdge<CommonNode>> graph) throws IOException {
Set<String> rows = new LinkedHashSet<>((int)graph.getEdgeCount());
for(CommonNode fromNode: graph.getNodes()) {
 for(CommonNode toNode: graph.adjacentTo(fromNode)) {
            String row = String.format(
                "%d %d 1",
                fromNode.getIdentity().intValue(),
                toNode.getIdentity().intValue()
            );
            rows.add(row);
           System.out.println(row);

            try {
                PrintWriter out;
                out = new PrintWriter( "/Users/......" );
                out.print(rows);
                out.close();
                //System.out.println(row);
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }
    }
    return rows;

}

score 0 · Answer 1 · answered Dec 17 '15 at 17:28

0

You open and close the PrintWriter in each iteration of the loop, overwriting the file every time. Open it before the loop and close it after.

answered Dec 17 '15 at 17:28

Kayaman

72,141
5
83
121

Keammoort · Answer 2 · 2015-12-17T17:46:42.180

0

You're overwriting a file with each row. Create PrintWriter once, write all output and then close it:

PrintWriter out = null;
try {
    out = new PrintWriter("path");
    for (CommonNode fromNode : graph.getNodes()) {
        for (CommonNode toNode : graph.adjacentTo(fromNode)) {
            String row = String.format("%d %d 1", fromNode.getIdentity().intValue(), toNode.getIdentity().intValue());
            rows.add(row);
            System.out.println(row);
            out.print(row);
        }
    }
} catch (FileNotFoundException e) {
    e.printStackTrace();
} finally {
    if (out != null) {
        out.close();
    }
}

edited Dec 17 '15 at 17:46

answered Dec 17 '15 at 17:29

Keammoort

3,075
15
20

Thx, but when i used this approach, I get the error ava:43: error: variable out might not have been initialized out.close(); – Okan Albayrak Dec 17 '15 at 17:41
@OkanAlbayrak this was caused by not handling an exception, please try it now. – Keammoort Dec 17 '15 at 17:47
Ok i Have fixed. You must only put the statement out = new PrintWriter( "/Users/......" ); above – Okan Albayrak Dec 17 '15 at 17:47
Now I got an new problem it outputs 0 1 11 2 11 3 1 without newline and a zero at the beginning – Okan Albayrak Dec 17 '15 at 17:50
I have fixed it with out.print(String.format("%s\n", row)); IntelliJ is super :)))))) – Okan Albayrak Dec 17 '15 at 17:53

Bug on Printstream. Only last statement ist writing

2 Answers2