Control space,numbers,special charaters,String in JTextfield in Java Swing

I have two textfield in my swing component. In one text field i need to have only numbers (no string,empty spaces,special charaters allowed) and in another textfield i need to have only string(no numbers,empty spaces,special charaters allowed). How can 开发者_运维技巧i implement that..???

You can use the Pattern Class (Regular Expressions) to validate the input. A short tutorial is available here.

I am pretty sure that the basic tutorial covers all this...

"^//d+$" //The text must have at least one digit, no other characters are allowed
"^[a-zA-Z]+$" //The text must have at least one letter, no other characters are allowed

You have two choices, you can validate the text in the fields either 1) on entry or 2) when the user performs an action such as clicks a confirmation button.

For 2) npinti's answer should steer you in the right direction, just get the value of the field and validate it with a regular expression.

For 1) you might want to write a KeyListener that intercepts key presses and only allows the correct type of character for the field.

You can extend javax.swing.text.PlainDocument class, and call setDocument method textfield. Here is one of the example ;

package textfield;
import java.awt.Toolkit;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;


public class LimitedValuePositiveIntegerDocument extends PlainDocument {

    int maxValue;
    int maxLength;
    Toolkit toolkit;

    /**
     * Constructor for the class.
     * @param max maximum value of the number
     */
    public LimitedValuePositiveIntegerDocument(int max){
        maxValue = max;
        maxLength = (""+max).length();
        toolkit = Toolkit.getDefaultToolkit();
    }

    /**
     * Inserts the input string to the current string after validation.
     * @param offs offset of the place where the input string is supposed to be inserted.
     * @param str input string to be inserted
     * @param a attribute set
     */
    @Override
    public void insertString(int offs, String str, AttributeSet a)
            throws BadLocationException {

        if(str == null)return;
        String currentText = getText(0,getLength());
        String resultText = new String();
        int i;
        boolean errorFound = false;
        boolean deleteFirstZero = false;
        int accepted=0;

        for (i = 0; (i<str.length())&&(!errorFound); i++) {
            if (Character.isDigit(str.charAt(i))) { /* if it is digit */
                if (offs==currentText.length()) {   /* calculates the resultant string*/
                    resultText = currentText+str.substring(0,i+1);
                } else if (offs==0) {
                    resultText = str.substring(0,i+1)+currentText;
                } else {
                    resultText = currentText.substring(0, offs)+str.substring(0,i+1)+currentText.substring(offs,currentText.length());
                }
                if (Integer.parseInt(resultText) > maxValue) {
                    errorFound = true;
                    toolkit.beep();
                } else {
                    if ( resultText.length() == maxLength+1) {
                        deleteFirstZero = true;
                    }
                    accepted++;
                }
            } else {
                errorFound = true;
                toolkit.beep();
            }
        }

        if ( accepted>0 ) { /* insert string */
            super.insertString(offs, str.substring(0,accepted), a);
            if (deleteFirstZero) {
                super.remove(0,1);
            }
        }
    }

    /**
     * Removes a part of the current string.
     * @param offs offset of the place to be removed.
     * @param len length to be removed
     */
    @Override
    public void remove(int offs, int len) throws BadLocationException{
        super.remove(offs, len);
    }

    /**
     * Returns max value of the number.
     * @return max value
     */
    public int getMaxValue() {
        return maxValue;
    }

    /**
     * Sets max value of the number.
     * @param max maximum value of the number
     */
    public void setMaxValue(int max) {
        this.maxValue = max;
    }
} // end of class

EDIT : and its usage;

LimitedValuePositiveIntegerDocument doc = new LimitedValuePositiveIntegerDocument(999);
JTextField numberField = new JtextField();
numberField.setDocument(doc);

You can only enter positive numbers less than 1000, and it check while you are pressing the key..