CODEWITHSUNDEEP
javastringparseint
Mona Jalal
Mona Jalal

Reputation: 38155

Converting String to int--java.lang.NumberFormatException.forInputString

Why would this not work and throw the following error?

System.out.println(Integer.parseInt("A5"));

Error is:

 at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
        at java.lang.Integer.parseInt(Integer.java:492)
        at java.lang.Integer.parseInt(Integer.java:527)
        at DecisionTreeImpl.createTree(DecisionTreeImpl.java:321)
        at DecisionTreeImpl.<init>(DecisionTreeImpl.java:59)

Also if this is not a good method for converting the strings like "A5" to integer, what's the way to do it correctly in Java?

I am given a class (and I am supposed not to modify it at all) which is like this:

public class DecTreeNode {
    Integer label; //for 
    Integer attribute;
    Integer parentAttributeValue; // if is the root, set to "-1"
    boolean terminal;
    List<DecTreeNode> children;

So when I am instantiating this class all the values which I need to pass to it (including attributes and labels are all string) so I have no idea what I should do now that Integer.ParseInt is failing me!

It is given as a hint that you might want to inherit from DecTreeNode class but I was not sure if that is related at all! Any idea how to tackle this problem?

root= new DecTreeNode((trainingSet.labels.get(getMajority(instances, trainingSet.labels.size())),trainingSet.attributes.get(biggestEntropy), -1, TRUE);

Here's the error I receive :

The constructor DecTreeNode(String, String, int, boolean) is undefined

However the problem is I am not allowed to modify the class DecTreeNode to have a new constructor.

Here's the complete DecTreeNode that is supposed not to be modified:

/**
 * Possible class for internal organization of a decision tree.
 * Included to show standardized output method, print().
 * 
 * Do not modify. If you use,
 * create child class DecTreeNodeImpl that inherits the methods.
 * 
 */
public class DecTreeNode {
    Integer label; //for 
    Integer attribute;
    Integer parentAttributeValue; // if is the root, set to "-1"
    boolean terminal;
    List<DecTreeNode> children;

    DecTreeNode(Integer _label, Integer _attribute, Integer _parentAttributeValue, boolean _terminal) {
        label = _label;
        attribute = _attribute;
        parentAttributeValue = _parentAttributeValue;
        terminal = _terminal;
        if (_terminal) {
            children = null;
        } else {
            children = new ArrayList<DecTreeNode>();
        }
    }

    /**
     * Add child to the node.
     * 
     * For printing to be consistent, children should be added
     * in order of the attribute values as specified in the
     * dataset.
     */
    public void addChild(DecTreeNode child) {
        if (children != null) {
            children.add(child);
        }
    }
}

Here's TrainingSet class:

public class DataSet {
    public List<String> labels = null;          // ordered list of class labels
    public List<String> attributes = null;      // ordered list of attributes
    public Map<String, List<String> > attributeValues = null; // map to ordered discrete values taken by attributes 
    public List<Instance> instances = null; // ordered list of instances
    private final String DELIMITER = ",";   // Used to split input strings

Upvotes: 0

Views: 10550

Answers (3)

monica
monica

Reputation: 502

It's telling you "The constructor DecTreeNode(String, String, int, boolean) is undefined" because your class DecTreeNode does not define a constructor with those data types. You can create a class DecTreeNodeImpl extending DecTreeNode(as the comments on the DecTreeNode class suggests) and implement all the methods/constructors that need parameters of type String.

Upvotes: 1

Alboz
Alboz

Reputation: 1851

Since we don't know how many letters there are (1 or more), I would personally go for something like this that removes all non-digits:

String labeledNumber="A5"

String str = labeledNumber.replaceAll("\\D+","");

System.out.println(Integer.parseInt(str));

This would work also with labels like: "abc12" "a-1232" etc.

Upvotes: 0

maszter
maszter

Reputation: 3720

If label is always one char, then solution is simple:

System.out.println(Integer.parseInt("A5".substring(1)));

Upvotes: 0

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