Попробуйте это:
String[] stringValues = jTextField1.getText().split(",");
//split the input "1,2,3,4" by "," result in array = ["1","2","3","4"]
int[] numArray= new int[stringValues.length];
for(int i=0; i<numArray.length; i++){
numArray[i]= Integer.parseInt(stringValues[i]);
//parse every string to int
}
String value ="";
for (int j = 0; j < numArray.length; j++) {
value += numArray[j] + ",";
//for each int in numArray ad: "numArray[j],"
}
//result is = "1,2,3,4,"
value = value.substring(0, value.length() - 1);
//remove last unused ","
jLabel1.setText( value );