What's the proper syntax to use for this NumberFormatException?

Question

I'm absolutely terrible at programming amd using stackoverflow atm, go easy on me, I'm trying to learn. From reading this code, what would be the proper syntax to use to avoid the NumberFormatExpection? `

package in.parapengu.spork.rotation;

import com.google.common.base.Charsets;
import in.parapengu.commons.utils.file.TextFile;
import in.parapengu.spork.Spork;
import in.parapengu.spork.exception.rotation.RotationLoadException;
import in.parapengu.spork.map.MapLoader;
import in.parapengu.spork.util.Log;

import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.util.ArrayList;
import java.util.List;

public class Rotation {

    private static int MAX_SIZE = 30;
    private static boolean OVERFLOW = true;

    private File file;
    private int index;
    private List<MapLoader> loaders;
    private List<RotationSlot> slots;

    public Rotation(File file, List<MapLoader> loaders, int index) {
        this.file = file;
        this.index = index;
        this.loaders = loaders;
        this.slots = new ArrayList<>();

        if(loaders.size() > MAX_SIZE && OVERFLOW) {
            for(MapLoader loader : loaders) {
                            try {


                slots.add(new RotationSlot(loader));
                            } catch(Exception ex) {
                    ex.printStackTrace();
                }    
            }
        } else {
                    try {
            while(slots.size() < MAX_SIZE) {
                for(int i = 0; i < loaders.size() && slots.size() < MAX_SIZE; i++) {
                    slots.add(new RotationSlot(loaders.get(i)));
                }

                if(slots.size() == 0) {
                    Log.warning("No slots were loaded");
                    break;
                } 
            }
        } catch(Exception ex) {
                    ex.printStackTrace();
                }    
                }
    }

    public Rotation(File file, List<MapLoader> loaders) {
        this(file, loaders, 0);
    }

    public File getFile() {
        return file;
    }

    public int getIndex() {
        return index;
    }

    public List<RotationSlot> getSlots() {
        return slots;
    }

    public boolean save() {
        TextFile file;
        try {
            file = new TextFile(this.file);
        } catch(IOException ex) {
                        ex.printStackTrace();
            Log.exception(ex);
            return false;
        }

        file.line(index + "");
        for(MapLoader loader : loaders) {
            file.line(loader.getName());
        }

        file.save();
        return true;
    }

    public static Rotation parse(File file) throws RotationLoadException {
        if(!file.exists()) {
            throw new RotationLoadException(file, file.getName() + " does not exist");
        }

        if(file.isDirectory()) {
            throw new RotationLoadException(file, file.getName() + " was a directory");
        }

        List<String> lines;
        try {
            lines = Files.readAllLines(file.toPath(), Charsets.UTF_8);
        } catch(IOException ex) {
                        ex.printStackTrace();
            throw new RotationLoadException(file, ex);
        } 

        String first = lines.get(0);
        int index;
        try {
            index = Integer.parseInt(first);
        } catch(NumberFormatException ex) {
                        ex.printStackTrace();
            throw new RotationLoadException(file, "The rotation index was not a valid number");

        } 

        lines.remove(0);
        List<MapLoader> maps = new ArrayList<>();
        for(String line : lines) {
            MapLoader loader = Spork.getMaps().getMap(line);
            if(loader == null) {
                throw new RotationLoadException(file, "Could not find a map matching \"" + line + "\"");
            }

            maps.add(loader);
        }

        return new Rotation(file, maps, index);
    }

}

`

Here's the error I get in console: `

[06:27:59 WARN]: java.lang.NumberFormatException: For input string: "1Test"
[06:27:59 WARN]:        at java.lang.NumberFormatException.forInputString(Unknow
n Source)
[06:27:59 WARN]:        at java.lang.Integer.parseInt(Unknown Source)
[06:27:59 WARN]:        at java.lang.Integer.parseInt(Unknown Source)
[06:27:59 WARN]:        at in.parapengu.spork.rotation.Rotation.parse(Rotation.j
ava:115)

`

Answer 1

Reason for NumberFormatException is because, you are trying to convert alpha numerics String "1Test" to number.

Try removing all the characters from your string like:

String name ="1Test";//why are you reading string?
Integer number = Integer.parseInt(name.replaceAll("[^0-9]", ""));
System.out.println(number);

You are catching the exception correctly and re-throwing RotationLoadException.