在 java 的 jlabel[] 中设置颜色值

Question

While I was writing a code, I found out that you can't do setColor to the Label I assigned. It tells me to put the length and put a variableDeclaration. However, I do not know ho to do that.. How do you assign a font type or a color for "JLabel[] answerLabels;"?

    JLabel[] answerLabels;
    answerLabels = new JLabel[question.getAnswers().length]; 
    answerLabels.length[new Font("PT Serif",Font.BOLD,16)];

Answer 1

I recommend you to learn more about arrays.

Look mate, you have an array(think of it as a list) of JLabel . Not a single JLabel

JLabel[] answerLabels;

The two square brackets [] after JLabel represent that you are creating an array, not a single JLabel .

Therefore, when you call,

answerLabels = new JLabel[question.getAnswers().length]; 
answerLabels.length[new Font("PT Serif",Font.BOLD,16)];

you are not referring to a JLabel but you are referring to an array. Since, array doesn't have any methods such as, setForeground() or setFont() , your program will run into an error.

So if you want to set the color or font of a particular JLabel , you have to refer to it. To refer to that JLabel , you have to write code as follows:

answerLabels[i].setForeground(Color.RED); 

Here, ' i ' represents the number of JLabel you want to access. Suppose, you want to access the third JLabel , then you have to write 2 in the place of 'i' in the above line.

Why 2, why not 3? Because arrays start at 0.

Note that, the JLabel you are trying to access should be initialized before setting it's color or font by something like,

answerLabels[i] = new JLabel();

Otherwise, your program will throw NullPointerException . So, make sure to initialize the JLabel you are accessing from the array before setting it's color or font.

Answer 2

It looks like your trying to do something like this:

    JLabel[] answerLabels = new JLabel[question.getAnswers().length];
    // This will loop through all of the JLabels and set the font and color
    for(int i=0; i<answerLabels.length; i++) {
        answerLabels[i] = new JLabel("Text from question/answer");
        answerLabels[i].setFont(new Font("PT Serif",Font.BOLD,16));
        answerLabels[i].setForeground(Color.red);
    }