Double[] List1 = {Mid1,Mid2,Mid3,Mid4,Mid5,Mid6,Mid7};
//System.out.println(Arrays.asList(List1));

Double MIN = (double) Collections.min(Arrays.asList(List1));
Double MAX = (double) Collections.max(Arrays.asList(List1));
//System.out.println(MIN);
//System.out.println(MAX);

Double TickLength = (MAX-MIN)/4;
//Double MinLength = MIN*0.99;
//Double MaxLength = MAX*1.01;
Double MinLength = MIN-(TickLength*0.2);
Double MaxLength = MAX+(TickLength*0.2);
/*
System.out.println(MAX);
System.out.println(MIN);
System.out.println(MaxLength);
System.out.println(MinLength);
System.out.println(TickLength);
*/

DefaultCategoryDataset dataset = new DefaultCategoryDataset();

dataset.setValue(Mid7, "Rate", date_7_2);
dataset.setValue(Mid6, "Rate", date_6_2);
dataset.setValue(Mid5, "Rate", date_5_2);
dataset.setValue(Mid4, "Rate", date_4_2);
dataset.setValue(Mid3, "Rate", date_3_2);
dataset.setValue(Mid2, "Rate", date_2_2);
dataset.setValue(Mid1, "Rate", date_1_2);

JFreeChart chart = ChartFactory.createLineChart("Exchange Rates in 7 Days", "Date", "Rate", dataset, PlotOrientation.VERTICAL, false, true, false);
chart.setBackgroundPaint(Color.white);
CategoryPlot plot = chart.getCategoryPlot();

NumberAxis axis = (NumberAxis) plot.getRangeAxis();
axis.setAutoRangeIncludesZero(false);
axis.setRange(MinLength,MaxLength);
axis.setTickUnit(new NumberTickUnit(TickLength));
ChartFrame frame = new ChartFrame("Exchange", chart);
frame.setSize(700,400);
frame.setVisible(true);