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Mortgage Calculator GUI

Posted on 2005-05-13
Medium Priority
Last Modified: 2008-01-09
Good Evening all. I am am getting the following error when I try to compile my program: "Week2_GUILayout is not abstract and does not override abstract method minimumLayoutSize (java.awt.Container) in java.awt.LayoutManager". Any ideas on how I can fix this? This is the first GUI I have done.  Also, is it necessary to have a container, or can I use a Flow Layout? Would that effect the outcome of my program? Other that a Container for the layout, what would work better?

import javax. swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import java.applet.Applet;

public class Week2_GUI extends JApplet{
      JLabel label_a;
      JLabel label_b;
      JLabel label_c;
      JTextField textfield_a;
      JTextField textfield_b;
      JTextField textfield_c;
      JButton calculate;
      JLabel label_d;
      JButton Start_Again;
      JLabel label_e;
      public static void main(String args[]){
            JFrame f = new JFrame("Mortgage Payment Calculator");
            Week2_GUI calc = new Week2_GUI();
      public void init(){
Week2_GUILayout customLayout = new Week2_GUILayout();

      Container con = getContentPane();

      label_a = new JLabel("Amount of Loan");

      label_b = new JLabel("Interest Rate");

      label_c = new JLabel("Term of Loan");

      textfield_a = new JTextField("");

      textfield_b = new JTextField("");
      textfield_c = new JTextField("");
      JButton calculate = new JButton("Calculate");
      label_d = new JLabel("Payment Amount");
      JButton Start_Again = new JButton("Start Again");
      label_e = new JLabel("$");
      calculate.addActionListener(new ActionListener(){
            public void actionPerformed (ActionEvent h)
                  double amount = Double.parseDouble(textfield_a.getText());
                  double interest = Double.parseDouble(textfield_b.getText());
                  interest = interest/100;
                  double term = Double.parseDouble(textfield_c.getText());
                  double payment=Math.round((amount*interest/12*Math.pow(interest/12+1,term*12))/(Math.pow(interest/12+1,term*12)-1));
      Start_Again.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent h)


class Week2_GUILayout implements LayoutManager{
      public Week2_GUILayout(){
public void addLayoutComponent(String name, Component comp){

public void removeLayoutComponent(Component comp){

public Dimension preferredLayoutSize(Container parent){
      Dimension t = new Dimension(0,0);
      Insets i = parent.getInsets();
      t.width = 539 + i.left + i.right;
      t.height = 394 + i.top + i.bottom;
      return t;

public void layoutContainer(Container parent){
      Insets i = parent.getInsets();
      Component w;
      w = parent.getComponent(0);
        if (w.isVisible()) {w.setBounds(i.left+8,i.top+8,96,24);}
        w = parent.getComponent(1);
        if (w.isVisible()) {w.setBounds(i.left+8,i.top+40,96,24);}
        w = parent.getComponent(2);
        if (w.isVisible()) {w.setBounds(i.left+8,i.top+72,96,24);}
        w = parent.getComponent(3);
        if (w.isVisible()) {w.setBounds(i.left+112,i.top+8,112,24);}
        w = parent.getComponent(4);
        if (w.isVisible()) {w.setBounds(i.left+112,i.top+40,112,24);}
        w = parent.getComponent(5);
        if (w.isVisible()) {w.setBounds(i.left+112,i.top+72,112,24);}
        w = parent.getComponent(6);
        if (w.isVisible()) {w.setBounds(i.left+112,i.top+104,112,24);}
        w = parent.getComponent(7);
        if (w.isVisible()) {w.setBounds(i.left+8,i.top+136,96,24);}
        w = parent.getComponent(8);
        if (w.isVisible()) {w.setBounds(i.left+112,i.top+192,112,24);}
        w = parent.getComponent(9);
        if (w.isVisible()) {w.setBounds(i.left+112,i.top+136,72,24);}

Question by:magmaya
  • 3
  • 2
LVL 92

Expert Comment

ID: 14001393

Add a method minimumLayoutSize(java.awt.Container) to the Week2_GUILayout class

LVL 92

Expert Comment

ID: 14001395
fillowing should do:

public Dimension minimumLayoutSize(Container container)
   return preferredLayoutSize(container);

Author Comment

ID: 14003706
Thank you! My program compiled well. For my mortgage payment formula. I don't like rounding up the payment. I was looking at http://www.javaworld.com/javaworld/jw-06-2001/jw-0601-cents.html, and I am trying to figure out how to have the full payment amount show... (w/ 2 decimal places) ex: $1113.67.  Any suggestions?

Author Comment

ID: 14003798
Also, would I change my GUI to use FlowLayout instead of hard coding the positions in the container?
LVL 92

Accepted Solution

objects earned 2000 total points
ID: 14004072
Use a NumberFormat

NumberFormat nf = NumberFormat.getCurrencyInstance();

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