Beginner Java Netbeans: How do I display for loop in jlabel?
Question
I have looked on this site and nothing has really answered my question. This is what my code looks like:
// declare user input variables
int min, max;
//assign user input to min and max
min = Integer.parseInt(Min.getText ());
max = Integer.parseInt(Max.getText ());
//use for loop to display the values
for (int n = min; n<= max; n++){
System.out.println(Integer.toString(n));
Output.setText(Integer.toString(n));
}
and the System.out.println () yields the correct answer. for instance, the user inputs 2 and 9, it will say:
run:
2
3
4
5
6
7
8
9
but the jLabel I'm trying to set the text to, Output, only displays 9. I know his might be stupidly simple but hey, I'm a beginner. Any help would be appreciated.
4 answers
solution1
2 ACCPTED 2013-11-14 03:02:18
The answer "depends".
Do you want each number on a new line or appended to the end of the String . Do you want them displayed individually like a counter?
If you want the numbers display in sequence, then you could use something like this...
JLabel label = new JLabel();
int min = 0;
int max = 10;
StringBuilder sb = new StringBuilder(128);
for (int n = min; n <= max; n++) {
sb.append(n);
}
label.setText(sb.toString());
Which will output something like...
Or if you wanted each number of a new line, you could use...
JLabel label = new JLabel();
int min = 0;
int max = 10;
StringBuilder sb = new StringBuilder(128);
sb.append("<html>");
for (int n = min; n <= max; n++) {
System.out.println(Integer.toString(n));
sb.append(n).append("<br>");
}
sb.append("</html>");
label.setText(sb.toString());
Which will output something like...
Now, if you want this, it would actually be easier to use a JTextArea and simply append each number to it...
JTextArea editor = new JTextArea(10, 10);
editor.setEditable(false);
int min = 0;
int max = 10;
StringBuilder sb = new StringBuilder(128);
for (int n = min; n <= max; n++) {
editor.append(Integer.toString(n) + "\n");
}
Which will output something like...
Now, if you want to animate it, you're going to need to do things different, either using a javax.swing.Timer or SwingWorker
solution2
0 2013-11-14 02:50:47
Every time you call System.out.println , it is writing the string you give it to STDOUT (aka your terminal). However, every time you call Output.setText , it is replacing the last string you set it to.
The solution would be to create a single string containing the concatenation of all the individual numbers and then send that string into Output.setText .
To create a string in a loop in Java you could do
// Create string "0\n1\n2\n3..."
String s = "";
for (int i=0; i<10; i++) {
s += i + "\n";
}
Alternatively, there is a class built into Java called StringBuilder which is preferred in situations where efficiency is a concern. Using + is very wasteful because it creates lots of intermediate objects that must be garbage collected.
StringBuilder s = new StringBuilder();
for (int i=0; i<10; i++) {
s.append(i);
s.append("\n");
}
solution3
0 2013-11-14 02:52:14
String nums = "";
for (..........) {
nums += yourResult + " "; // this will give a space separating your output
}
label.setText(nums);
Keep adding to the String every iteration, then just set the final text to the label.
solution4
0 2015-08-09 23:37:03
This is what I'd normally do:
String vals = "";
int min = Integer.parseInt(Min.getText ());
int max = Integer.parseInt(Max.getText ());
for (int i = min; i <= max; i++)
vals = vals + Integer.toString(i) + " ";
output.setText(vals);
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