How to restrict entering whitespaces as input to JTextField elements in Java Swing?-CodePudding

I'm using Java Swing for a Connection GUI. I need to prevent entering whitespaces to the JTextField elements, especially to password field. I had used isEmpty() or isBlank() to know whether whitespaces are entered. But it didn't worked. If I enter whitespace it doesn't return true value,as isBlank() should return true if there is whitespace only.

String errorMessage = "No Errors"; //Intializing as No errors

private boolean checkValueAndSetErrorMessage(Map<String, String> map) {

    boolean truth = false;
    for (Map.Entry<String, String> mapElement : map.entrySet()) {
        if (mapElement.getKey().isEmpty()|| mapElement.getKey().isBlank()) {
            
            errorMessage = String.format("%1$s should not be blank.", mapElement.getValue()); //Changing errorMessage to empty
            truth = false; 
            break;
        } else {
            truth = true;
        }
    }
    return truth;

}

CodePudding user response：

Try :

mapElement.getKey().contains(" ")

CodePudding user response：

You can use regular expression to test if the key contains any whitespace character.

Pattern.matches("\\s ", mapElement.getKey())

For more explanation in the regular expression that I provided,

\s mean that it will try to match one or more whitespaces characters