Java - How to set String as static int

Question

I have a method that accepts only a String.

public void setVerticalAlignment(String align) {
            ...
    gd.verticalAlignment = align;   // accepts only          


        

Answer 1

Why are you using a text field? There are only a few legal choices for alignments, so you should really use something like a JComboBox instead. You could store custom objects in the JComboBox so that they display the named constant but also store the integer constant:

public class SwingAlignOption {
  public final String name;
  public final int value;
  public SwingAlignOption(String name, int value) {
    this.name = name;
    this.value = value;
  }
  public String toString() { return name; }
}

Then you can add instances to the combo-box like comboBox.addItem(new SwingAlignOption("TOP", SWT.TOP)).

Note that JComboBox changed between Java 6 and 7. In the Java 7 libraries JComboBox is generic, which makes it easier to store custom objects like this inside and retrieve their values later. In Java 6 you'll have to use a cast when you access the selected value.

Answer 2

If you use Java 7 you can always use switch on Strings:

switch (align) {
    case "SWT.TOP":
        gd.verticalAlignment = SWT.TOP;
    /* etc */
}

Being honest I would avoid using strings like "STW.TOP". If I really had to store alignment state in the other way than just int I would use enums which might be used in switch in older versions of Java.

Answer 3

Sounds like you want a map:

// Ideally use ImmutableMap from Guava
private static final Map<String, Integer> ALIGNMENTS = mapAlignments();

private static final Map<String, Integer> mapAlignments() {
    Map<String, Integer> ret = new HashMap<String, Integer>();
    ret.put ("SWT.TOP", SWT.TOP);
    // etc
    return ret;
}

Then you can just fetch from the map (and unbox) later.

Or, better, change your method declaration to avoid this in the first place :)

Answer 4

Integer.parseInt(String)

can throw a NumberFormatException if the string is not specified as integer value. Also in prev versions of java, you cant apply switch-case on Strings. So better you can use the following :

if(("SWT.TOP").equals(align))
{
     gd.verticalAlignment = SWT.TOP;
}