#cs106a

again just marveling at the subtle beauty of Prof Sahami’s - Stanford code - it’s simple - minimal & yet very deep (at least 2me)

i have to look again to see other code usage of the ivar - which - stores an object’s state in-between method calls (that’s a mouthful)

ie- instance variable - so named bc it relates to instances - instantiation - a new instance of a class (ie an object)

transl: an ivar stores values & those values persist & aren’t lost at the close of any particular method

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but what i just noticed is: he actually makes use of the ivar & illustrates effective efficient use of it - i have to look carefully at other code - i think in the other code - usually - ivar’s are declared & then used only once

iff: ur only using an ivar once - (i realize) it’s more efficient to make the variable local - to the 1 usage - in a method

I’m looking at his Incrementor - Counter program - which is so simple & yet subtle & profound - perhaps profound just because of its simplicity

But he uses the counter ivar - 4 (technically 5) times - once to declare it - importantly uninitialized (to allow different usages later)

twice in overloaded constructors (that’s 3 times - counting how many times he uses the ‘counter’ ivar)  & 4th inside a method (5th he increments the counter - counter++)

& the program outputs the effect of the different usages of that 1 instance variable (he also lectures in a clever & funny way about - persistence of the primitive variable (ivar) - when he says: it should “bother you” - why should it bother me ? ) - funny that i look at it now & hell yeah it bothered me!

changes to the primitive variable should NOT effect the caller- method - the changes shouldn’t persist - or - should they - what a great lesson

package com.stanfordjava.to.StandardJava; import static java.lang.System.out; import java.util.Arrays;

     public class Iglo0 {          //private static final int SENTINEL = 0;            private static final int MAX_SIZE = 5;

         public static void main(String[] args){              new Iglo0().runMehran();          }          public void runMehran(){

             int keepCount = 0; // int numScores              int[] values = new int[MAX_SIZE];// int[] mid

             int i=0;

                 while(i<MAX_SIZE){                      int random= (int)(Math.random()*10); // int score                          out.print("random value is: " + random);

                // if(random == SENTINEL)                        //break;   // *can't use 'break' outside loop or switch*

                        values[keepCount++] = random;                  out.println("   -and-   keepCount is:  " + keepCount);                         i++;                                                                                               /* ima put BuckyCode here:  ++arrayVar[1+randomVar.nextInt(6) ] - also: enthuware has some vry cool code like this in Sample quest’s - re - forLoop */

                 }                  out.println(Arrays.toString(values)); // Output: [8, 7, 0, 4, 4]           }     }

/*  OUTPUT: random value is: 8   -and-   keepCount is: 1 random value is: 7   -and-   keepCount is: 2 random value is: 0   -and-   keepCount is: 3 random value is: 4   -and-   keepCount is: 4 random value is: 4   -and-   keepCount is: 5

[8, 7, 0, 4, 4] */

//=== *How2 Use SENTINEL & ‘break’ (above) ===//

Surround if statement in a while loop:

     while(true){                     if(userInput.hasNextLine()){                         userInput.nextLine();                     }                 break;                 } {i sort of did do that - but - didn’t work - intervening code}

//Like this:

import static java.lang.System.out; //import static java.lang.Math.random; import java.util.Scanner; import java.util.Arrays;

     public class Stanf_16 implements Runnable{

//Static Field Constants:          private static final int MAX_SIZE = 5;          private static final int SENTINEL = -1;

// readInt equivalent: userInput + hasNextInt() + nextInt()      static Scanner userInput = new Scanner(System.in);

         Stanf_16(){              super();      }      public static void main(String[] argzilla){          Stanf_16 s = new Stanf_16();          s.run();          userInput.close(); //closes resources }//close main      public void run(){          int[] testN = new int[MAX_SIZE];         int numScores = 0; //int x = (int)(random() * 5);      while(true){          out.print("Enter a test score: ");              if(userInput.hasNextInt()){                  int score = userInput.nextInt();          if(score == SENTINEL) break;              testN[numScores++] = score; //Assign each new userInput score to an //index in the array (1st) & then (post) increment the index by 1 (after)

     }//close if    }//close while         out.println(Arrays.toString(testN));   }//close run }//close class

//========== lect16 code snippet:

   public void run(){

        int[] mid= new int[MAX_SIZE];

        int numScores = 0;

    while(true){

       int score = readInt( “ ? “);

            if(score== SENTINEL) break;

       mid[numScores++] = score;

    }

This is number 2 from handout #4 : string processing.

/* * RemoveAllOccurences */

import acm.program.*;

public class RemoveAllOccurences extends ConsoleProgram{ public void run(){ while(true){ // infinite loop String str1 = readLine(“Give…

This stumped me for a while but I was able to get the solution after several days of trial and error. I don’t know if this is the right way to do it. But it seems to work.

/** * ** */ import acm.program.*; import java.awt.*; public class Commas extends…

This is a ridiculous game that I was able to build just by following Stanford’s CS106a. This is almost a complete game. The main part is done .It just needs a little polishing. I am moving on to the next assignment for now.

/* * File: Breakout.java *…

Mouse events with java.

/* * DrawLines.java * draw lines in canvas * ralph @today * */ import acm.graphics.*; import acm.program.*; import java.awt.event.*; public class Drawlines extends GraphicsProgram { public void run(){ /* Tell Java that we're ready…

I am so proud of myself that I figured it out how to fit the circles on the window. I was stuck for a while but I finally figured it out today.

/** * Circle.java - Make random circles * @author rafiks */ import java.awt.Color; import acm.graphics.*;…