如何将小写字母转换为大写字母&小写字母和小写字母 [英] how to convert Lower case letters to upper case letters & and upper case letters to lower case letters

问题描述

交替显示在文本框中键入的任何文本

Alternately display any text that is typed in the textbox

//     in either Capital or lowercase depending on the original
//     letter changed.  For example:  CoMpUtEr will convert to
//     cOmPuTeR and vice versa.
    Switch.addActionListener(new ActionListener()
    {
        public void actionPerformed(ActionEvent e )

            String characters = (SecondTextField.getText()); //String to read the user input
            int length = characters.length();  //change the string characters to length

         for(int i = 0; i < length; i++)  //to check the characters of string..
         {             
            char character = characters.charAt(i);          

            if(Character.isUpperCase(character)) 
            {
                SecondTextField.setText("" + characters.toLowerCase());

            }
            else  if(Character.isLowerCase(character))
            {
                 SecondTextField.setText("" + characters.toUpperCase()); //problem is here, how can i track the character which i already change above, means lowerCase**
                }               
         }}     
    });

推荐答案

setText 正在将文本内容更改为您提供的内容，而不是附加它。

setText is changing the text content to exactly what you give it, not appending it.

转换字符串从现场开始，然后直接应用...

Convert the String from the field first, then apply it directly...

String value = "This Is A Test";
StringBuilder sb = new StringBuilder(value);
for (int index = 0; index < sb.length(); index++) {
    char c = sb.charAt(index);
    if (Character.isLowerCase(c)) {
        sb.setCharAt(index, Character.toUpperCase(c));
    } else {
        sb.setCharAt(index, Character.toLowerCase(c));
    }
}

SecondTextField.setText(sb.toString());

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