java的。不接受0作为文本字段中的第一个输入

Question

我正在使用Java，我的代码的这一部分用于在只接受数字，后退空格和删除的文本字段中输入年龄。如果代码是第一个字符，我怎么能告诉代码避免接受0？

谢谢。

以下是代码：

private void tfAgeKeyTyped(java.awt.event.KeyEvent evt) {                               

    char c = evt.getKeyChar();

    if(!(Character.isDigit(c)) || (c == KeyEvent.VK_BACK_SPACE) || (c == KeyEvent.VK_DELETE)){
        evt.consume();
    }
}

Answer 1

您只需要在当前输入为空时使用0 检查您输入的字符是否等于c == '0' ：

if((this.currentInput.isEmpty() && (!Character.isDigit(c) || c == '0')) || !(Character.isDigit(c)) || (c == KeyEvent.VK_BACK_SPACE) || (c == KeyEvent.VK_DELETE)){
    evt.consume();
}

Answer 2

private void tfAgeKeyTyped(final java.awt.event.KeyEvent evt) {                               

    final char c = evt.getKeyChar();

    // You need access to the current input to known if you are on the 
    // first character or not. 
    // Here I assume it exists as a private member variable. 
    final boolean isFirstChar = this.currentInput.isEmpty();

    final boolean isValidEvent = (Character.isDigit(c) && !(isFirstChar && c == '0')) || 
        (c == KeyEvent.VK_BACK_SPACE) || 
        (c == KeyEvent.VK_DELETE);

    if (isValidEvent) {
        evt.consume();
    }
}