I'm new here, and I got a problem when I'm trying to read a file.
Here is my code
public void openFile()
{
try
{
if(Board.state == Board.STATE.LEVEL1)
{
scan = new Scanner(new File("D://OOP Photos//Map.txt"));
}
}
catch(FileNotFoundException e)
{
e.printStackTrace();
}
try
{
if(Board.state == Board.STATE.LEVEL2)
{
scan = new Scanner(new File("D://OOP Photos//Map1.txt"));
}
}
catch(Exception e)
{
System.out.println("Error loading MAP !!! ");
}
try
{
if(Board.state == Board.STATE.LEVEL3)
{
scan = new Scanner(new File("D://OOP Photos//Map2.txt"));
}
}
catch(Exception e)
{
System.out.println("Error loading MAP !!! ");
}
}
If I comment out the if statement it is okay, but if I leave it there, it will throw a NullPointerException
in the next method:
public void readFile()
{
while(scan.hasNext())
{
for(int i = 0; i < 10; i++)
{
if(scan.hasNext())
{
Map[i] = scan.next();
}
}
}
}
Can you help me ?
Thank You :)
Do something like this:
public static void main(String args[]) {
String filename;
if(Board.state == Board.STATE.LEVEL1) {
filename = "D://OOP Photos//Map1.txt";
}
else if (Board.state == Board.STATE.LEVEL2) {
filename = "D://OOP Photos//Map2.txt";
}
else if (Board.state == Board.STATE.LEVEL3) {
filename = "D://OOP Photos//Map3.txt";
}
readFile(filename);
}
public void readFile(String filename) {
try {
Scanner scan = new Scanner(new File(filename));
int i = 0;
while(scan.hasNext()) {
Map[i] = scan.next();
i++;
}
}
catch(FileNotFoundException e) {
System.out.println("Error loading MAP !!! ");
}
}
Before each IF statement simply print out the values of Board.state
and Board.STATE.LEVELx
? That will tell you exactly why your IFs are all false. Or just set a breakpoint and inspect the values.
Also try changing your ==
in the IFs to .equals()
.
Your app logic makes me confused. Why not jsut make simple public Scanner openFile(String filePath) method, with one try / catch block, with one Scanner scan = new Scanner(new File(filePath))
?
Here's something to consider:
public static class Board {
// I'm assuming this is what's happening?
public static State state = State.LEVEL1;
public enum State {
LEVEL1("Map.txt"), LEVEL2("Map1.txt"), LEVEL3("Map2.txt");
private final String fileName;
private State(String fileName) {
this.fileName = fileName;
}
public String getFileName() {
return fileName;
}
}
};
public void openFile() {
if (Board.state == null)
throw new RuntimeException("board state not set");
File file = new File("D:/OOP Photos/", Board.state.getFileName());
try (Scanner scan = new Scanner(file)) {
// do the scanning
} catch (FileNotFoundException fnfe) {
// handle file not found
} catch (Exception e) {
// handle other errors
}
}
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