I want to decrease the font size if text doesn't fit in JLabel

Question

There were many posts regarding this problem, but i couldn't understand the answers given by people in there. Like in this post: "How to change the size of the font of a JLabel to take the maximum size" the answer converts the font size to 14! But that is static and further in other answers; their whole output screen seems to increase.

I display certain numbers in a JLabel named "lnum", it can show numbers upto 3 digits but after that it shows like "4..." I want that if the number is able to fit in the label, it should not change its font size but if like a number is 4 digit, it should decrease the font size in such a way that it fits. NOTE: i do not want that the dimensions of the jLabel change. I just want to change the text in It.

Edit: Here is what code i tried

String text = lnum.getText();        
System.out.println("String Text = "+text);//DEBUG
Font originalFont = (Font)lnum.getClientProperty("originalfont"); // Get the original Font from client properties            
 if (originalFont == null) { // First time we call it: add it
        originalFont = lnum.getFont();
        lnum.putClientProperty("originalfont", originalFont);
    }
 int stringWidth = lnum.getFontMetrics(originalFont).stringWidth(text);       

 int componentWidth = lnum.getWidth();
 stringWidth = stringWidth + 25; //DEBUG TRY
 if (stringWidth > componentWidth) { // Resize only if needed
        // Find out how much the font can shrink in width.
        double widthRatio = (double)componentWidth / (double)stringWidth;

        int newFontSize = (int)Math.floor(originalFont.getSize() * widthRatio); // Keep the minimum size

        // Set the label's font size to the newly determined size.
        lnum.setFont(new Font(originalFont.getName(), originalFont.getStyle(), newFontSize));
    }else{
        lnum.setFont(originalFont); // Text fits, do not change font size
        System.out.println("I didnt change it hahaha");//DEBUG 
 }
    lnum.setText(text);

I have a problem that many a times it doesn't work, like if the text is "-28885" it shows "-28...".

stringWidth = stringWidth + 25; //DEBUG TRY

I had to add this code so that it increases the length that it gets. It was a code i added to just temporarly fix the problem. I want a permanent solution for this.

Check the second answer of the question you referred to: http://stackoverflow.com/a/2715279/1098603 — Matthieu, Oct 05 '13 at 06:36
@Matthieu I had read that post but the problem is that i can hardly understand what he is trying to explain. and in the image that he had shown, the output window, jlabel increase but i dont want that; i want to adjust (decrease) the font size to fit it into the same window - jlabel — , Oct 05 '13 at 06:42
He is basically computing the size required by the text in `stringWidth` and compares it to the size of the `JLabel` in `componentWidth` to compute `widthRatio`. I'll develop in an answer. — Matthieu, Oct 05 '13 at 06:52
@Matthieu One more thing; i am not able to use Font "labelFont = lnum.getFont();" properly — , Oct 05 '13 at 06:54
@Matthieu Therefore i don't want to take it (as it doesnt take the font i have choose) Rather i want something like this: Font labelFont = "Times New Roman"; (BUT this doest work) — , Oct 05 '13 at 06:55

score 2 · Accepted Answer · edited May 23 '17 at 11:57

Adapted from an answer on the question you referred to:

void setTextFit(JLabel label, String text) {
    Font originalFont = (Font)label.getClientProperty("originalfont"); // Get the original Font from client properties
    if (originalFont == null) { // First time we call it: add it
        originalFont = label.getFont();
        label.putClientProperty("originalfont", originalFont);
    }

    int stringWidth = label.getFontMetrics(originalFont).stringWidth(text);
    int componentWidth = label.getWidth();

    if (stringWidth > componentWidth) { // Resize only if needed
        // Find out how much the font can shrink in width.
        double widthRatio = (double)componentWidth / (double)stringWidth;

        int newFontSize = (int)Math.floor(originalFont.getSize() * widthRatio); // Keep the minimum size

        // Set the label's font size to the newly determined size.
        label.setFont(new Font(originalFont.getName(), originalFont.getStyle(), newFontSize));
    } else
        label.setFont(originalFont); // Text fits, do not change font size

    label.setText(text);
}

When you'll display a number that would fit, you should reset the Font back to its original (see the else part).

EDIT: If you can't/don't want to keep a reference to the original Font, you can save it as a "client property" (see the first lines).

I am having problem using the code for text if it is a negative number — , Oct 05 '13 at 08:00
@user2203870 It doesn't change. In the end, the `JLabel` will be displaying a String. Only the width of that String matters. Where is exactly your problem? — Matthieu, Oct 05 '13 at 08:10

I want to decrease the font size if text doesn't fit in JLabel

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