Nolan Yardley
Reputation: 45
Access Modifiers in Java (static)
I got this program here and I combined the two classes into one for practice purposes. (Thanks to sir who helped me.) However, I got an error and that is "No enclosing instance of type QuineMcCluskey is accessible. Must qualify the allocation with an enclosing instance of type QuineMcCluskey." in the method initTerm.
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
public class QuineMcCluskey extends JFrame implements ActionListener, WindowListener{
private final long serialVersionUID = 1L;
static ArrayList<Term>[][] table=new ArrayList[5][5]; // SERVES AS OUR STORAGE FOR ARRANGING TERMS AND TO OUR RESULTING TERMS THAT ARE BEING COMPARED.
static Vector<String> inputTerm= new Vector <String>(); // STORES OUR ORIGINAL INPUT/NUMBERS
static Vector<String> resultingTerms= new Vector <String>(); // STORES RESULTING TERMS FOR EACH SET OF COMPARISON
static int var=0; //NUMBER OF VARIABLE
static int numbers=0; //NUMBER OF INPUTS
final static int maxTerms=1000; //MAXIMUM NUMBER OF TERMS WITH SAME NUMBER OF 1'S
static TextField result = new TextField(" ",50);
static TextField text;
static TextField text1;
static QuineMcCluskey qWindow;
static String finalT = "";
public static void main(String[] args){
qWindow = new QuineMcCluskey("Quine-McCluskey Simulator"); //creates a window
qWindow.setSize(400,250); //sets the size of the window
qWindow.setVisible(true); //makes the window visible
qWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE ); //CLOSES THE WINDOW WHEN CLOSING OR CLICKING THE X BUTTON
JOptionPane.showMessageDialog(null, "Welcome to my Quine-McCluskey Simulator!"); //DISPLAYS MESSAGE
}//end main
public static int count_one(String temp){ //COUNT 1'S FROM EACH TERM
int count=0;
char[] tempArray=temp.toCharArray();
int i=0;
while(i<temp.length()){
if(tempArray[i]=='1'){
count++;
}
i++;
}//end while
return count;
}//end one
public static void getPrimeImplicants(){ // PAIRS TERMS UNTIL NOTHING TO PAIR, END TERMS ARE OUR PRIME IMPLICANTS
table=createTermTable(inputTerm);
printTermTable();
createPairing();
}
public static ArrayList<Term>[][] createTermTable(Vector <String> input){ // CREATE TABLE, ARRANGES TERMS BASED ON THE NUMBER OF 1'S IN
//EACH TERM USING count_one,therefore, row 1 contains terms with 1 1 bit.
Term temp;
int one=0;
int element=0;
ArrayList[][] arrayLists = new ArrayList[var+1][maxTerms+1]; //CREATES AN ARRAY WITH VAR ROWS CORRESPONDING TO POSSIBLE NUMBER OF
// 1 FOR EACH TERM AND 1000 COLUMNS
ArrayList<Term> [][]tempTable = arrayLists;
for(int x=0;x<=var;x++){ //?
for(int y=0;y<=maxTerms;y++){
tempTable[x][y]= new ArrayList<Term>();
}//end y
}//end for x
for(int i=0;i<input.size();i++){
one=count_one(input.get(i)); //COUNT 1'S FROM EACH TERM
temp=initTerm(input.get(i),false); // INITIALIZE PROPERTIES OF THAT TERM
while(!tempTable[one][element].isEmpty()){
element++;
}//end while
tempTable[one][element].add(temp);
element=0;
} //end for
return tempTable;
}//end createTermTable
public static Term initTerm(String n,boolean u){ //INITIALIZE USED and NUM PROPERTY OF THE TERM
Term term=new Term();
term.used=u; // TO INDICATE IF THE TERM IS ALREADY PAIRED
term.num=n; // THE TERM ITSELF
return term;
}//end initTerm
public static void printTermTable(){ // PRINTS THE COMPUTATION/TABLES
System.out.println("\nCOMPUTING:");
for(int i=0;i<var+1;i++){
System.out.print(i);
System.out.println(" --------------------------------------------");
for(int j=0;!table[i][j].isEmpty();j++){ //PRINTS TERM ON EACH ROW WHILE TERM IS NOT EMPTY
System.out.println(table[i][j].get(0).num);
}//end for j
}//end for i
}
public static void createPairing(){ //PAIRS A TERM TO EACH TERM ON THE NEXT ROW
int finalterms=0;
String term_num="";
int found=0;
Vector<String> preResult= new Vector<String>();
for(int x=0;x<=var-1;x++){ // REPEATS PAIRING OF A TERMS OF THE TABLE VAR TIMES TO MAKE SURE WHAT ARE LEFT ARE PRIME IMPLICANTS
preResult=new Vector<String>(); // STORES THE RESULTING TERMS FOR EACH SET OF PAIRING
for(int i=0;i<=var;i++){ //COMPARES A ROW WITH EACH TERMS ON THE NEXT ROW
//Vector <String> rowResult= new Vector<String>(); //STORES RESULTING TERMS ON THAT PARTICULAR TERM OF THE ROW. THIS IS TO AVOID REPETITIONS
for(int j=0;!table[i][j].isEmpty();j++){ // TERM ON THE ROW BEING COMPARED WITH EACH TERM ON NEXT ROW
if(i+1!=var+1) // MAKES SURE THAT THE PROCESS NOT EXCEEDS THE ARRAYBOUND
for(int k=0;!table[i+1][k].isEmpty();k++){ //TERM ON THE NEXT ROW THAT IS BEING COMPARED WITH TERM ON THE CURRENT ROW.
term_num=pair(table[i][j].get(0).num,table[i+1][k].get(0).num); //ASSIGNS RESULT OF PAIRING TO term_num
if(term_num!=null){ // IF PAIRING IS SUCCESSFUL
table[i+1][k].get(0).used=true; // TERM IS PAIRED/USED
/*if(!rowResult.contains(term_num)){ //MAKES SURE THAT TERM IS NOT REPEATE
rowResult.add(term_num);
found=1;
}
*/
if(!preResult.contains(term_num)){ // MAKES SURE THAT TERM IS NOT REPEATED
preResult.add(term_num);
found=1;
finalterms++; // COUNTS THE FINAL/RESULTING TERMS FOR THIS SET OF PAIRING
}//end if !resultingTerms
found=1;
}//end if term_num!=null
}//end for k
if(found==0){ // IF TERM IS NOT SUCCESSFULLY PAIRED/USED, ADD TO THE RESULTING TERMS FOR THIS SET
if(table[i][j].get(0).used!=true){
preResult.add(table[i][j].get(0).num);
}
}
found=0;
}//end for j
}//end for i
table=createTermTable(preResult); // CREATE ANOTHER TABLE FOR NEXT SET. THE NEW TABLE CONTAINS THE RESULTING TERMS OF THIS SET
if(preResult.size()!=0)
resultingTerms=preResult; //IF THE ARE RESULTING TERMS, THEN PRINT AND ASSIGN TO resultingterms. THE END VALUE OF resultingterms WILL BE SIMPLIFIED
printTermTable();
}//end for x
}//end createPairing
public static String pair(String a,String b){
int difference=-1;
char []array1 = new char[a.length()];
char []array2;
for(int i=0;i<var;i++){
array1=a.toCharArray(); //CONVERTS TERMS OF TYPE STRING TO TERMS OF TYPE CHAR
array2=b.toCharArray();
if(array1[i]!=array2[i]){ // IF NOT EQUAL FOR A PARTICULAR CHARACTER FOR THE FIRST TIME, THEN GET THE INDEX CORRESPONDING TO THAT CHARACTER.
if(difference==-1)
difference=i;
else //IF NOT NOT EQUAL FOR THE FIRST TIME, THEN THE TERMS DIFFER IN MORE THAN 1 PLACE
return null;
}//end if
}//end for
if(difference==-1) //THE TERMS ARE INDENTICAL, RETURN NULL, PAIRING UNSUCCESSFUL
return null;
char[] result= a.toCharArray(); //CHARACTER CORRESPONDING TO THE INDEX WHERE TERMS DIFFER ONLY ONCE WILL BE CHANGED TO '-'
result[difference]='-';
String resulTerm= new String(result);
return resulTerm; //RETURNS THE MODIFIED TERM, PAIRING SUCCESSFUL
}//end pair
public static void simplifymore(){ //SIMPLIFY THE RESULTINGTERMS
int primes=resultingTerms.size(); // RESULTING TERMS CORRESPOND TO OUR PRIME IMPLICANTS
int[][] s_table= new int[primes][numbers]; //CREATES A TABLE WITH ROWS EQUAL TO NUMBER OF PRIME IMPLICANTS AND COLUMNS EQUAL TO THE NUMBER OF THE ORIGINAL INPUT
for(int i=0;i<primes;i++){
for(int j=0;j<numbers;j++){
s_table[i][j]=implies(resultingTerms.get(i),inputTerm.get(j));
}//end for j
}//end for i
Vector <String> finalTerms= new Vector<String>(); // STORES THE FINALTERMS
int finished=0;
int index=0;
while(finished==0){ //UNTIL ALL ELEMENTS ARE NOW TURNED TO 0
index=essentialImplicant(s_table);
if(index!=-1)
finalTerms.add(resultingTerms.get(index)); // IF RESULTING TERM IS THE ONLY ONE IMPLYING THE CURRENT ORIGINAL TERM, THEN ADD TO FINAL TERMS
else{ // THOSE THAT HAVE MORE THAN ONE IMPLICATION FOR A PARTICULAR ORIGINAL TERM
index=largestImplicant(s_table);
if(index!=-1)
finalTerms.add(resultingTerms.get(index)); //ADD TO FINAL TERMS IF LARGEST IMPLICANT(ONE WHICH HAS MORE NUMBER OF 1'S. SEE COMMENTS ON largestImplicant.
else
finished=1; //IF INDEX IS -1 THEN ALL ELEMENTS HAVE ALREADY BEEN DELETED OR HAVE MADE VALUE 0
}//end else
}//end while finished
System.out.println("Final Terms :");
for(int x=0;x<finalTerms.size();x++) //PRINTS THE FINAL TERMS IN BINARY FORMAT
System.out.println(finalTerms.get(x));
printSimplified(finalTerms);
}//end simplifymore
public static void printSimplified(Vector <String> finalTerms){
String temp="";
char[] tempArray;
char variables[]= {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'}; //basis for our variables to printed
int index=0;
int i=0;
int j=0;
System.out.print("F = ");
while(i<finalTerms.size()){ //until all final terms are printed in algebraic form.
temp=finalTerms.get(i); //assigns current final term to temp
tempArray=temp.toCharArray(); //CONVERTS TEMP TO ARRAY
while(j<var){
if(tempArray[j]=='-'){ //IGNORES -
index++;
}
else if (tempArray[j]=='0'){
finalT+=variables[26-var+index]+"'"; // PRINTS THE CORRESPONDING LETTER.IF CHARACTER IS 0 THEN APPEND ' AFTER THE VARIABLE
index++;
}
else if (tempArray[j]=='1'){
finalT+=variables[26-var+index]; // PRINTS CORRESPONDING LETTER
index++;
}
else{};
j++;
}//end while
if(i<finalTerms.size()-1)
finalT+=" + "; // APPENDS +
i++;
temp="";
j=0;
index=0;
}//end while
System.out.println(finalT);
}//print simplified
public static int essentialImplicant(int[][] s_table){ // CHECKS EACH RESULTING TERM IMPLYING A PARTICULAR ORIGINAL TERM
for(int i=0;i<s_table[0].length;i++){ //
int lastImplFound=-1;
for(int impl=0;impl<s_table.length;impl++){
if(s_table[impl][i]==1){ //IF RESULTING TERM IMPLIES ORIGINAL TERM
if(lastImplFound==-1){
lastImplFound=impl;
}else{ // IF MORE THAN ONE IMPLICATION,THEN IT IS NOT AN ESSENTIAL PRIME IMPLICANT.GO TO NEXT ORIGINAL TERM
lastImplFound=-1;
break;
}//end else
}
}
if(lastImplFound!=-1){ // ONE IMPLICATION FOR THE ORIGINAL TERM. THIS IS AN ESSENTIAL PRIME IMPLICANT
implicant(s_table,lastImplFound);
return lastImplFound;
}
}//end for impl
return -1;
}
public static void implicant(int [][] s_table,int impA){ // DELETE OR MAKE VALUE 0 THE ROW WHERE THE ESSENTIAL PRIME IMPLICANT IS AND THE COLUMNS OF ALL THE ORIGINAL TERMS IMPLIED BY IT
for(int i=0;i<s_table[0].length;i++){
if(s_table[impA][i]==1)
for(int impB=0;impB<s_table.length;impB++){
s_table[impB][i]=0;
}
}
}//end implicant
public static int largestImplicant(int[][] s_table){
int maxImp=-1;
int max=0;
for(int imp=0;imp<s_table.length;imp++){ // LOCATES WHICH HAS MORE NUMBER OF 1'C IN EACH PRIME
int num=0;
for(int i=0;i<s_table[0].length;i++){
if(s_table[imp][i]==1)
num++;
}//end for i
if(num>max){ // TERM WITH MORE 1'S AT THE END OF THE LOOP WILL BE ADDED TO THE FINAL TERMS
max=num;
maxImp=imp;
}//end if num>max
}//end for imp
if(maxImp!=-1){ // IF WE HAVE SUCCESSFULLY LOCATED A PRIME IMPLICANT
implicant(s_table,maxImp); // DELETE OR MAKE VALUE 0 THE ROW WHERE THE ESSENTIAL PRIME IMPLICANT IS AND THE COLUMNS OF ALL THE ORIGINAL TERMS IMPLIED BY IT
return maxImp;
}//end if maxImp!=-1
return -1;
}
public static int implies(String term1, String term2){ // RETURNS 1 IF RESULTING TERM IMPLIES THE ORIGINAL TERM, 0 OTHERWISE
char[] term1Array=term1.toCharArray();
char[] term2Array=term2.toCharArray();
//EX. ORG TERM IS 100100, RES TERM IS 1--10- ,RESULTING TERM IMPLIES THE ORIGINAL TERM. SINCE - HERE IS TREATED AS 0 OR 1
for(int i=0;i<var;i++){
if(term1Array[i]!=term2Array[i] && term1Array[i]!='-')
return 0;
}
return 1;
}
//end class
public QuineMcCluskey (String name){
super(name); //ASSIGNS LABEL OF THE WINDOW
setLayout(new GridLayout(1, 1)); //SETS THE LAYOUT
setLocation(350,200); //SETS THE LOCATION OF THE WINDOW ON THE SCREEN
GridBagLayout gridbag = new GridBagLayout(); //used to align buttons
GridBagConstraints constraints = new GridBagConstraints();//to specify the size and position for the gridbaglayout
setLayout(gridbag);
constraints.weighty = 1; //distributes spaces among columns
constraints.weightx = 1; //distributes spaces among rows
constraints.gridwidth = GridBagConstraints.REMAINDER; //to specify that the component be the last one in its column
Label label1 = new Label(" How many variables does the function have?"); //CREATES A LABEL
label1.setVisible(true); //MAKES THE LABEL VISIBLE, ASSIGNS NEW FONT AND COLOR THEN ADD TO THE WINDOW
label1.setFont(new Font("Sans Serif", Font.BOLD, 12));
label1.setBackground(Color.CYAN);
add(label1);
text1= new TextField("",10);
gridbag.setConstraints(text1,constraints); //applies constraints to text
text1.setEditable(true); //SO THAT WE COULD STILL HAVE AN UNLIMITED LENGTH OF INPUT
text1.setForeground(Color.black);
text1.setBackground(Color.white);
text1.setVisible(true);
text1.addActionListener(this); //ACTIVATES ACTIONLISTENER FOR THIS FIELD
add(text1);
label1 = new Label(" Please list all the minterms that evaluates to 1:");//CREATES LABEL
gridbag.setConstraints(label1,constraints);
label1.setVisible(true); //MAKES THE LABEL VISIBLE, ASSIGNS NEW FONT AND COLOR THEN ADD TO THE WINDOW
label1.setBackground(Color.green);label1.setFont(new Font("Sans Serif", Font.BOLD, 12));
label1.setBackground(Color.CYAN);
add(label1);
text = new TextField("Enter your numbers here separated by a comma",50);
gridbag.setConstraints(text,constraints); //applies constraints to text
text.setEditable(true); //ENABLES UNLIMITED LENGTH OF INPUT
text.setForeground(Color.black);
text.setBackground(Color.white);
text.setVisible(true);
text.addActionListener(this); //ACTIVATES ACTIONLISTENER FOR THIS FIELD
text.setForeground(Color.blue);
add(text);
JButton enter = new JButton ("Enter"); // CREATES BUTTON NAMED Enter
enter.setVisible(true); //MAKES IT VISIBLE, APPLIES THE CONSTRAINTS, AND ADD TO THE WINDOW
add(enter);
enter.setBackground(Color.green);
enter.addActionListener(this); //ACTIVATES ACTIONLISTENER
gridbag.setConstraints(enter,constraints);
JButton reset = new JButton ("Reset"); // CREATES BUTTON NAMED Reset
reset.setVisible(true); //MAKES IT VISIBLE, APPLIES THE CONSTRAINTS, AND ADD TO THE WINDOW
gridbag.setConstraints(reset,constraints);
reset.setBackground(Color.green);
add(reset);
reset.addActionListener(this);
label1 = new Label(" Result:");
gridbag.setConstraints(label1,constraints);
label1.setVisible(true);
label1.setBackground(Color.cyan);
label1.setFont(new Font("Sans Serif", Font.BOLD, 12));
label1.setBackground(Color.CYAN);
add(label1);
result = new TextField(" ",50);
gridbag.setConstraints(result,constraints); //applies constraints to text
result.setEditable(true);
result.setForeground(Color.black);
result.setBackground(Color.white);
result.setVisible(true);
add(result);
}
public void actionPerformed(ActionEvent e) {
String stringInput="";
String numOfVar="";
String temp="";
String temp1="";
int num=0;
if(e.getActionCommand() == "Enter"){ // IF Enter BUTTON IS CLICKED
stringInput = text.getText(); // GETS STRING INPUT FROM TEXT(MINTERMS)
numOfVar = text1.getText(); //GETS STRING INPUT FROM TEXT1(VARIABLES)
var = Integer.parseInt(numOfVar); //CONVERTS numOfVar TO INTEGER
StringTokenizer token= new StringTokenizer(stringInput," ,"); //TOKENIZE INPUT. ELIMINATE ALL COMMAS AND SPACES
while(token.hasMoreTokens()){ //WHILE THERE ARE MORE TOKENS
temp1=token.nextToken(); //GETS TOKEN
numbers++; //COUNTS THE NUMBER OF INPUTS
num=Integer.parseInt(temp1); //CONVERT INPUT TO INTEGER
temp=Integer.toBinaryString(num); //CONVERTS INTEGER FORM OF INPUT TO BINARY IN ITS PROPER LENGTH BASED ON THE NUMBER OF VARIABLES GIVEN
if(temp.length()!=var){
while(temp.length()!=var){
temp="0"+temp;
}
}
inputTerm.add(temp); //ADDS RESULT(BINARY FORM) TO inputTerm
}//end while
getPrimeImplicants(); //GET PRIMEIMPLICANTS
simplifymore(); // SIMPLIFY MORE
result.setText(finalT); // DISPLAYS THE RESULT (SIMPLIFIED) TO RESULT TEXTFIELD
}//end if
if(e.getActionCommand()== "Reset"){ //RESETS THE VALUES FOR NEXT SET OF INPUTS
var=0;
table=new ArrayList[5][5]; // SERVES AS OUR STORAGE FOR ARRANGING TERMS AND TO OUR RESULTING TERMS THAT ARE BEING COMPARED.
inputTerm= new Vector <String>(); // STORES OUR ORIGINAL INPUT/NUMBERS
resultingTerms= new Vector <String>(); //STORES THE RESULTING TERMS FOR EACH COMPUTATION
finalT=""; //STORES THE FINAL TERMS IN THEIR ALGEBRAIC FORM
numbers=0; //COUNTS THE NUMBER OF INPUTS FROM THE USER
text.setText(""); //ERASE THE TEXTS DISPLAYED ON THE TEXT FIELDS
text1.setText("");
result.setText("");
}
}
public void windowActivated(WindowEvent e) {}
public void windowClosed(WindowEvent e) {qWindow.setVisible(false);} //CLOSES THE WINDOW AFTER PROGRAMS STOPS RUNNING
public void windowClosing(WindowEvent e) {}
public void windowDeactivated(WindowEvent e) {}
public void windowDeiconified(WindowEvent e) {}
public void windowIconified(WindowEvent e) {}
public void windowOpened(WindowEvent e) {}
public class Term {
public String num;
public boolean used;
}
}//end class
I was told that I must remove the keyword static so I did and this one error happened. Can you please help me manipulate the code? I'm practicing OOP and I want to learn more about these static modifiers. Thank you very much!
Upvotes: 1
Views: 668
Answers (3)
user207421
Reputation: 311048
I must remove the keyword static
You must not remove the keyword static on the declaration of serialVersionUID.
You haven't confided in us which line of code gets that compile error, but clearly something around it also must be static.
Never just follow advice blindly. Always ask what it means and whether it really applies to everything you have done. There's a lot of cut-and-paste, programming-by-rote, and cargo-cult programming in this business. Don't be part of it, no matter where it comes from. Sadly a fair proportion of it is going to come from your colleagues and superiors. You have to learn how to deal with that.
Upvotes: 2
Peter Lawrey
Reputation: 533870
When you use static you are saying there is no implied object I am using here. However you have not define Term as static, you you are saying it needs to b in an Object.
In your case the simplest thing to do is to make Term static as it doesn't appear to need to be non-static.
static class Term {
String num;
boolean used;
}
In general I would make nested classes static wherever possible. Partly for performance but mostly for clarity.
Upvotes: 3
Amit Deshpande
Reputation: 19185
Term is inner class so you create instance of inner class like below
Term term = qWindow.new Term();
More help available here
Upvotes: 0
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