how to convert Lower case letters to upper case letters & and upper case letters to lower case letters

java, lowercase, string, uppercase

Solution

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

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());

Problem

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** } }} }); ```

Original source

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