Thread: using java.util.InputMismatchException with try

iv writen this code in order to prevent an unexpected ending of program in case there is an input mismatch

static int smartInputInt ()
	{
		boolean flag=true;
		int end=-10;
		while (flag)
		{
			flag=false;
			try
			{
				end=reader.nextInt ();
			}
			catch (java.util.InputMismatchException e)
			{
				System.out.println ("Intput Error !");
				flag=true;
			}
		}
		return end;
 
	}

the problem with this code is that if a wrong input is inserted it causes a loop that never ends that prints "Intput Error !"
how can i fix this problem?

remove line

flag=true;

in your catch() method
this way you only fall through it once. Your in a while loop while true...

I do understand. You don't stop to read the input line when in the Reader. you never clear out the IO stream out so you always get get same input. Use a if statement in the try catch to stop this. or clear out the stream and/or get another user inputs.

If coding was easy then anyone can do it.

add the code all of it just working with a method I am not going to write the code I have other code to write.

JFreeChart crap....

want to see my test stuff. this test was to get it working on its own then import it to my project. I should have 3 of these charts stacked on top of each other were the display shows multiple lines. Each chart has different user controls.

package components;
 
import java.awt.Dimension;
import java.awt.HeadlessException;
 
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartFrame;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PlotOrientation;
import org.jfree.data.xy.XYSeries;
import org.jfree.data.xy.XYSeriesCollection;
 
/**
 *
 * @author William
 */
public class XYPlotJfreeChart extends JFrame {
 
    JPanel panel;
    XYSeries series1;
    ArrayList<Point2D> list;
    Random ran = new Random();
 
    public XYPlotJfreeChart() {
 
 
//        XYPlotJfreeChart chart = new XYPlotJfreeChart();
        panel = new JPanel();
        series1 = new XYSeries("first");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
        getData();
 
XYSeriesCollection dataset = new XYSeriesCollection();
dataset.addSeries(series1);
 
JFreeChart panel = ChartFactory.createXYAreaChart(
        "MyTitle", //title
        "X", //x axis label
        "Y", //y axis label
        dataset, //data set
        PlotOrientation.HORIZONTAL,
        true, //show legend
        true,  //use tooltips
        false); //configure chart to generate url's
ChartFrame frameChart = new ChartFrame("MyChart Title", panel);
 
frameChart.setVisible(true);
frameChart.setSize(400, 400);
 
    }
 
    public static void main(String[] args) {
        XYPlotJfreeChart xy = new XYPlotJfreeChart();
//        Dimension d = new Dimension(400, 400);
//        xy.setMinimumSize(d);
//        xy.setMaximumSize(d);
//        xy.setVisible(true);
    }
 
    private void init() {
 
 
    }
 
    private void getData() {
        list = new ArrayList<Point2D>();
        longPause();
long time = 0;
        for (int i = 0; i < 30; i++) {
 
            Point2D points = new Point2D() {
 
                long time;
                double x;
                double y;
 
                @Override
                public double getX() {
                    return x;
                }
 
                @Override
                public double getY() {
                    return y;
                }
 
                public long getTime() {
                    return time;
                }
 
                public void setTime(long t) {
                    time = t;
                }
 
                @Override
                public void setLocation(double d, double d1) {
                    x = d;
                    y = d1;
                }
            };
 
            points.setLocation(ran.nextDouble() * 180, ran.nextDouble() * 180);
            points.setTime(time);
            list.add(points);
//            System.out.println("x point "+ points.getX());
//            System.out.println("y point " + points.getY());
 
            time += 15;
            series1.add(points.x, points.y);
        }
 
    }
 
    private void printList() {
        Iterator<Point2D> l = list.listIterator();
 
        while (l.hasNext()) {
            Point2D p = l.next();
            System.out.println("");
            System.out.println("TIME " +p.getTime());
            System.out.println("x point " + p.getX());
            System.out.println("y point " + +p.getY());
 
        }
    }
 
    private void longPause() {
//        System.out.println("paused ");
        for (int i = 0; i < 1000000; i++) {
            //do nothing just a counting loop
        }
    }
}
 
class Point2D {
 
    long time;
    double x;
    double y;
 
    public double getX() {
        return x;
    }
 
    public double getY() {
        return y;
    }
 
    public long getTime() {
        return time;
    }
 
    public void setTime(long t) {
        time = t;
    }
 
    public void setLocation(double d, double d1) {
        x = d;
        y = d1;
    }
}

this is a lot more complexed then i thought it would be i think i will pass since i cant understand most of this code

Well, part of the reason you don't understand his code is because it's not documented well. Also, your longPause method should just sleep the thread, otherwise you risk crashing/overloading the poor users game.. I generally do create a second method instead of constantly using a try-catch statement. (I personally think that it should be an error, not an exception).

/**
 * Delays the program for the specified amount of seconds.  Handles InterruptedException with a call to printStackTrace() and returning
*/
public void longPause(int seconds)
{
  long delay = (long)seconds * 1000;
  try
  {
     Thread.sleep(delay);
  }catch(InterruptedException e)
  {
     e.printStackTrace();
     return;
  }
}

Just scanned most of the code, that stood out.

Its not documented cause i wrote the entire thing.

Why would you think I don't under stand this code?

Its junk code, I use test each component before adding it to the project. This tiny peace is not even close to what I am building. This is just for display to correct my values.

Im going home:: have a good night

        Scanner reader = new Scanner(System.in);
 
        boolean flag = true;
        int end = -10 ;
 
       do{
            try {
                System.out.println("in here");
                end = reader.nextInt();
                System.out.println("end is " + end);
            } catch (InputMismatchException e) {
                System.out.println("Intput Error !" +e.toString());
                System.out.println("end is " + end);
                flag = false;
            }
        }while (flag);
    }

You should always document anything you create.

Originally Posted by william

Its not documented cause i wrote the entire thing.

Which is exactly why it should be documented.

well, i didnt understand this code since the only import i know is java.util.*

yes,my question hasnt queit been answered , i would like to know if there is a simpler way of making a loop with java.util.InputMismatchException in try.
somthing that doesn't involve any complexed import.i'm just a high school student and i wants to make a simple checkers game
more efficient so that i could get some extra credit on the assignment