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ArrayIndexOutOfBoundsException - Scoreboard with images

I am trying to make a scoreboard with images in processing, with images from 0 to 9, but any number greater than 9 does not make changes
It should be something like this: 10, 11, 12, ..., 99
but it only changes the number on the left, try using a counter, converting it to a String and then to a Char[] to get the first digit of two numbers; for example: 25, it would have to be 2
when passing that number to the array, it sends "ArrayIndexOutOfBoundsException"
char[] digits;
PImage [] prueba = new PImage[10];
int contadorPrueba2 = 0;
int aa = 0;
void setup () {
size (781, 470);
tablero = loadImage("tablero.png");
flechaRight = loadImage("flechaRight.png");
flechaLeft = loadImage("flechaLeft.png");
for (int i = 0; i < prueba.length; i++) {
prueba[i] = loadImage("numero_" + i + ".jpg");
}
}
void draw () {
//flechas
image(flechaRight, x, y);
image(flechaLeft, x2, y);
image(prueba[0], x3, 50);
//cambiar de numeros
image(prueba[contadorPrueba2], x4, 50);
image(prueba[aa], x3, 50);
}
boolean isMouseOver (int x, int y, int w, int h) {
if (mouseX>x && mouseX <x+w && mouseY>y && mouseY <y+h) {
return true;
}
return false;
}
void mousePressed () {
if (isMouseOver (x, y, w, h) == true) {
contadorPrueba2++;
//image(uno, x3, 50);
} else if (isMouseOver (x2, y, w, h) == true) {
contadorPrueba2--;
}
if (contadorPrueba2 >= prueba.length)
contadorPrueba2 = 0;
count = String.valueOf(contadorPrueba2);
digits = count.toCharArray();
for (int i = 0; i < digits.length; i++) {
if (contadorPrueba2 >= 10) {
//aa = digits[0];
println(digits[i]);
aa = digits[i];
//aa = digits[i];
//print("pp" + aa);
if (i == 0) {
print("ksk" + digits[i]);
}
}
}
}

Chars aren't exactly the best way to keep track of a score, which can make for some headache at times. I strongly suggest that you keep track of the score with an integer number unless you really have no choice on the matter.
Now, to translate an integer into a bunch of index numbers associated with images of said numbers, things can also become complicated, but I got your back! In fact, you can use MATH and solve this quite easily. Are you familiar with the modulo operator? If you're not, read about it because it's a programmer's best friend. Long story short, it's a division that returns only the leftover numbers after the division. As an example, if I write:
10 / 3 == 3.333333 // as a division this makes sense
10 % 3 == 1 // modulo only keeps what's left when the division stops being an integer
because: 10 == [3+3+3] + 1
Ok, you probably already knew this, but if you didn't, now you do. Here's how I use this knowledge to simplify your issue with a commented example:
PImage[] digits = new PImage[10];
int score = 4780; // you can change this number for whatever integer number
void setup () {
size(200, 200);
for (int i = 0; i < digits.length; i++) {
digits[i] = loadImage(i + ".png"); // these 10 images are 10x10 pixels for easier handling
}
}
void draw () {
int i=1;
int j = 160; // arbitrary number: this is where i start drawing the score (the rightest number)
// oooh! This is a good opportunity to use a do...while(); loop! I don't have that many of those.
// This is because we have to show at least ONE digit even if the score is zero, but I coded this so you can have a score higher than 99 without issue
do {
i*=10; // using multiples of 10 with the modulo operator
// as we use base 10 in real life, multiples of 10 help isolate digits of interests
image(digits[(score%i)/(i/10)], j, 90); // j is the x coordinate of the current digit, 90 is an arbitrary y coordinate
// 'digits[(score%i)/(i/10)]' deserves an explanation:
// 'score%i' removes every unit besides the current digit of interests, as an example if we're looking for the hundreds digit of 3456 it'll be 400
// '/(i/10)' removes the unwanted zero (in the 3456 example it would leave only the number 4 instead of 400)
j-=10; // updating j for the next digit
} while(i<score);
}
I know I didn't tell you why you get ArrayIndexOutOfBoundsException and it's kinda on purpose: this is a very common error and although I have no trouble guessing why you get it, it's just more efficient to fix by improving the method than by meddling with the code. There are many articles on SO about why this error happens and I encourage you to read at least one, as it'll be something that you'll see again in the future. Yet, for now, you can just avoid it by switching to this method.
I hope this helps. Have fun!

RandomWalk solution issue

PROBLEM
I am working on a code where I am simulating a dog walking in a city - trying to escape the city. The dog makes random choices of which way to go to at each intersection with equal probability.If stuck at a dead end the dog will come directly back to the middle of a big city and start all over again. The dog will do this again and again until it gets out of the city or until it gets tired after T number of trials. But by the time the the dog starts again from the middle(N/2,N/2) on each try, it will have forgotten all the intersections it had visited in the previous attempt.
IDEA
The idea is to mimic a code given in our textbook and come up with the solution. We were given input N, T - where N is the number of north-south and east-west streets in the city and T is the number of times the dog will try to get out of the city before it gives up. We have to draw it out, using StdDraw. We have been given how to make random movements - generate a number between 0 and 4 - up: 0 right: 1 down: 2 left: 3
My Approach
import java.util.Random;
public class RandomWalk {
private static final Random RNG = new Random (Long.getLong ("seed",
System.nanoTime()));
public static void main(String[] args) {
int N = Integer.parseInt(args[0]); // lattice size
int T = Integer.parseInt(args[1]); // number of trials
int deadEnds = 0; // trials resulting in a dead end
StdDraw.setCanvasSize();
StdDraw.setXscale(0,N);
StdDraw.setYscale(0,N);
// simulate T self-avoiding walks
for (int t = 0; t < T; t++) {
StdDraw.clear();
StdDraw.setPenRadius(0.002);
StdDraw.setPenColor(StdDraw.LIGHT_GRAY);
for(int i=0;i<N;i++){
StdDraw.line(i, 0, i, N);
StdDraw.line(0, i, N, i);
}
StdDraw.setPenColor(StdDraw.RED);
StdDraw.setPenRadius(0.01);
boolean[][] a = new boolean[N][N]; // intersections visited
int x = N/2, y = N/2; // current position
// repeatedly take a random step, unless you've already escaped
while (x > 0 && x < N-1 && y > 0 && y < N-1) {
int t_x = x;
int t_y=y;
// dead-end, so break out of loop
if (a[x-1][y] && a[x+1][y] && a[x][y-1] && a[x][y+1]) {
deadEnds++;
break;
}
// mark (x, y) as visited
a[x][y] = true;
// take a random step to unvisited neighbor
int r = RNG.nextInt(4);
if (r ==3) {
//move left
if (!a[x-1][y])
t_x--;
}
else if (r == 1 ) {
//move right
if (!a[x+1][y])
t_x++;
}
else if (r == 2) {
//move down
if (!a[x][y-1])
t_y--;
}
else if (r == 0) {
//move up
if (!a[x][y+1])
t_y++;
}
StdDraw.line(t_x, t_y, x, y);
x = t_x;
y = t_y;
}
System.out.println("T: "+t);
}
System.out.println(100*deadEnds/T + "% dead ends");
}
}
ISSUE
Given N - 15, T - 10, -Dseed=5463786 we should get an output like - http://postimg.org/image/s5iekbkpf/
I am getting - see http://postimg.org/image/nxipit0pp/
I don't know where I am going wrong. I know this is very specific in nature, but I am really confused so as to what I am doing wrong. I tried all 24 permutations of 0,1,2,3 but none of them gave the output desired. So, I conclude that the issue in in my code.

check your StdDraw.java with:
http://introcs.cs.princeton.edu/java/stdlib/StdDraw.java.html
your code should be fine, I got the expected result

Optimizing an algorithm [compile ready code]

Problem from game perspective (Poker)
The player has 2 green chips (5 points) and 1 blue (10 points). This totals 20 points. Now the player want to buy a ingame icon that costs 16 points. The player has enough money to buy the item. So the player pays 16 points, but what points will he give to the shop to pay correctly.
Now I've written a working example with all of the work done.
Code
Program.java
import java.util.Arrays;
public class Program {
public static void main(String[] args) {
// Setting up test environment
Player player = new Player("Borrie", new int[]{0,0,0,0, 230});
int itemCost = 16626;
// Pay for item
System.out.printf("First we check if the player can pay with it's current ChipSet");
if (!player.canPayWithChipSet(player.getChips(), 5)) {
if (player.exchangeChips(5)) {
System.out.printf("\n\nThe players ChipSet:" + Arrays.toString(player.getChips().chips));
System.out.printf("\nThe players ChipSet has been succesfully exchanged.");
} else {
System.out.printf("\n\nThe players ChipSet:" + Arrays.toString(player.getChips().chips));
System.out.printf("\nThe players ChipSet was not able to be exchanged.\n");
}
} else {
System.out.printf("\n\nThe player can pay exact with it's original ChipSet. No need to exchange.");
}
}
}
Player.java
import java.util.ArrayList;
import java.util.Arrays;
public class Player {
private String name;
private ChipSet chips;
private int points = 0;
public Player(String name, int[] chips) {
this.name = name;
this.chips = new ChipSet(chips);
this.points = this.chips.getSum();
}
public boolean exchangeChips(int cost) {
ChipSet newChipSet = exchangePlayerChipSet(this.chips.getChips(), cost);
if (newChipSet == null) {
return false;
}
this.chips = newChipSet;
return true;
}
public ChipSet exchangePlayerChipSet(int[] originalChipValues, int cost) {
ChipSet newChipSet = null;
// Create possible combinations to compare
ArrayList<ChipSet> chipSetCombos = createCombinations(this.chips.getChips());
// Filter the chipset based on if it's able to pay without changing chips
System.out.printf("\n\n---- Filter which of these combinations are able to be payed with without changing chips ----");
ArrayList<ChipSet> filteredCombos = filterCombinations(chipSetCombos, cost);
// Compare the filtered chipsets to determine which one has changed the least
if (!filteredCombos.isEmpty()) {
newChipSet = compareChipSets(originalChipValues, filteredCombos);
}
return newChipSet;
}
private ArrayList<ChipSet> createCombinations(int[] array) {
ArrayList<ChipSet> combos = new ArrayList<>();
int[] startCombo = array;
System.out.printf("Player has " + getTotalPoints(startCombo) + " points in chips.");
System.out.printf("\nPlayer has these chips (WHITE,RED,GREEN,BLUE,BLACK): " + Arrays.toString(startCombo));
while (startCombo[4] != 0) {
startCombo = lowerBlack(startCombo);
if (getTotalPoints(startCombo) == points) {
combos.add(new ChipSet(startCombo));
}
}
while (startCombo[3] != 0) {
startCombo = lowerBlue(startCombo);
if (getTotalPoints(startCombo) == points) {
combos.add(new ChipSet(startCombo));
}
}
while (startCombo[2] != 0) {
startCombo = lowerGreen(startCombo);
if (getTotalPoints(startCombo) == points) {
combos.add(new ChipSet(startCombo));
}
}
while (startCombo[1] != 0) {
startCombo = lowerRed(startCombo);
if (getTotalPoints(startCombo) == points) {
combos.add(new ChipSet(startCombo));
}
}
System.out.printf("\n\n---- Creating variations on the players chips ----");
System.out.printf("\nVariation (all worth " + getTotalPoints(startCombo) + " points):\n");
int counter = 1;
for (ChipSet a : combos) {
System.out.printf("\nCombo " + counter + ": " + Arrays.toString(a.getChips()));
counter++;
}
return combos;
}
private ArrayList<ChipSet> filterCombinations(ArrayList<ChipSet> combinations, int cost) {
ArrayList<ChipSet> filteredChipSet = new ArrayList<>();
combinations.stream().filter((cs) -> (canPayWithChipSet(cs, cost))).forEach((cs) -> {
filteredChipSet.add(cs);
});
return filteredChipSet;
}
// This method has be worked out
public boolean canPayWithChipSet(ChipSet cs, int cost) {
ChipSet csOrig = new ChipSet(cs.chips);
ChipSet csCopy = new ChipSet(cs.chips);
int counterWhite = 0, counterRed = 0, counterGreen = 0, counterBlue = 0, counterBlack = 0;
while (20 <= cost && cost > 0 && csOrig.getChips()[4] != 0) {
csOrig.getChips()[4] -= 1;
cost -= 20;
counterBlack++;
}
while (10 <= cost && cost > 0 && csOrig.getChips()[3] != 0) {
csOrig.getChips()[3] -= 1;
cost -= 10;
counterBlue++;
}
while (5 <= cost && cost > 0 && csOrig.getChips()[2] != 0) {
csOrig.getChips()[2] -= 1;
cost -= 5;
counterGreen++;
}
while (2 <= cost && cost > 0 && csOrig.getChips()[1] != 0) {
csOrig.getChips()[1] -= 1;
cost -= 2;
counterRed++;
}
while (1 <= cost && cost > 0 && csOrig.getChips()[0] != 0) {
csOrig.getChips()[0] -= 1;
cost -= 1;
counterWhite++;
}
if (cost == 0){
System.out.printf("\nCombo: %s can pay exact. With %d white, %d red, %d green, %d blue an %d black chips", Arrays.toString(csCopy.chips),counterWhite,counterRed,counterGreen,counterBlue,counterBlack);
return true;
} else {
System.out.printf("\nCombo: %s cannot pay exact.\n\n\n", Arrays.toString(csCopy.chips));
return false;
}
}
private ChipSet compareChipSets(int[] originalChipValues, ArrayList<ChipSet> chipSetCombos) {
ChipSet newChipSet;
int[] chipSetWaardes = originalChipValues; // originele chipset aantal van kleur
int[] chipSetCombosDifferenceValues = new int[chipSetCombos.size()];
int counter = 1;
System.out.printf("\n\n---- Calculate differences between players stack and it's variations ----");
for (ChipSet cs : chipSetCombos) {
int amountWhite = cs.getChips()[0];
int amountRed = cs.getChips()[1];
int amountGreen = cs.getChips()[2];
int amountBlue = cs.getChips()[3];
int amountBlack = cs.getChips()[4];
int differenceWhite = Math.abs(chipSetWaardes[0] - amountWhite);
int differenceRed = Math.abs(chipSetWaardes[1] - amountRed);
int differenceGreen = Math.abs(chipSetWaardes[2] - amountGreen);
int differenceBlue = Math.abs(chipSetWaardes[3] - amountBlue);
int differenceBlack = Math.abs(chipSetWaardes[4] - amountBlack);
int totalDifference = differenceWhite + differenceRed + differenceGreen + differenceBlue + differenceBlack;
chipSetCombosDifferenceValues[counter - 1] = totalDifference;
System.out.printf("\nCombo " + counter + ": " + Arrays.toString(cs.getChips()) + " = " + totalDifference);
counter++;
}
newChipSet = chipSetCombos.get(smallestValueOfArrayIndex(chipSetCombosDifferenceValues));
System.out.printf("\n\nThe least different ChipSet is: " + Arrays.toString(newChipSet.getChips()) + " ");
return newChipSet;
}
private int smallestValueOfArrayIndex(int[] array) {
int currentValue = array[0];
int smallestIndex = 0;
for (int j = 1; j < array.length; j++) {
if (array[j] < currentValue) {
currentValue = array[j];
smallestIndex = j;
}
}
return smallestIndex;
}
private int[] lowerBlack(int[] array) {
return new int[]{array[0], array[1], array[2], array[3] + 2, array[4] - 1};
}
private int[] lowerBlue(int[] array) {
return new int[]{array[0], array[1], array[2] + 2, array[3] - 1, array[4]};
}
private int[] lowerGreen(int[] array) {
return new int[]{array[0] + 1, array[1] + 2, array[2] - 1, array[3], array[4]};
}
private int[] lowerRed(int[] array) {
return new int[]{array[0] + 2, array[1] - 1, array[2], array[3], array[4]};
}
private int getTotalPoints(int[] array) {
return ((array[0] * 1) + (array[1] * 2) + (array[2] * 5) + (array[3] * 10) + (array[4] * 20));
}
public String getName() {
return this.name;
}
public int getPoints() {
return this.points;
}
public ChipSet getChips() {
return chips;
}
}
ChipSet.java
public class ChipSet {
public static final int WHITE_VALUE = 1;
public static final int RED_VALUE = 2;
public static final int GREEN_VALUE = 5;
public static final int BLUE_VALUE = 10;
public static final int BLACK_VALUE = 20;
public static final int[] VALUES = new int[]{WHITE_VALUE, RED_VALUE, GREEN_VALUE, BLUE_VALUE, BLACK_VALUE};
protected int[] chips;
public ChipSet(int[] chips) {
if (chips == null || chips.length != 5) {
throw new IllegalArgumentException("ChipSets should contain exactly 5 integers!");
}
// store a copy of passed array
this.chips = new int[5];
for (int i = 0; i < this.chips.length; i++) {
this.chips[i] = chips[i];
}
}
public int getSum() {
return chips[0] * WHITE_VALUE
+ chips[1] * RED_VALUE
+ chips[2] * GREEN_VALUE
+ chips[3] * BLUE_VALUE
+ chips[4] * BLACK_VALUE;
}
public int[] getChips() {
return this.chips;
}
}
Some explanation:
Create combinations
We create some submethods the trade a chip in for it's lower chip. So
for example black = 2 blues. Then we create 5 loops in order. The
first ones checks if there are still black chips, if so reduce 1 black
add 2 blues. Save this new combination in a list if the sum of the
chips in the new ChipSet equals the original ChipSets value. Loop
continues until there are no blacks anymore. Then it check if there
are blues and repeats the same process until there are no reds
anymore. Now we have list with all possible variations of X value in
chips.
Filter combinations
You filter the ChipSets based on
if you can pay X points with them without exchanging. We loop over all
possible combinations of ChipSets created in the previous part. If you
can pay with the ChipSet without exchanging add it to the filteredList
of ChipSets. The result is a filered list with only valid ChipSets.
Calculate difference
For each ChipSet we count the number of chips of all colors in a
ChipSet and substract the original chipset number of chips with it.
You take the absolute value of that and make a sum of all those
differences of the original and the combos colors. Now we have a
number that represents the difference from the original. Now all we
have to do is compare all the ChipSets ´difference number´. The one
with the least difference we use to assign to the player.
So what it basically does is: It checks first if the current ChipSet can be used to pay and returns a boolean just like you asked. If it can it doesn't do anything, otherwise it goes through the 3 sub-algorithms and defines the best ChipSet (one to able to use to pay and least different one) and changes the players ChipSet the it
So now what is my question, how would I start to optimize this? I ask this because when there are bigger inputs the algorithm easily uses a few seconds.

Profile the application a few times to see which methods take the most time with accuracy. For example:
Try to optimize those methods which you know are the bottlenecks and reprofile until your bottlenecks are out.

Let me tell you how to find the problem(s). Here's what to do:
Get it running and hit "pause". Display the call stack. Click on each level, and it will show you a line of code where some method/function A calls some B, and the reason why is evident from the context. Put all those reasons together, and you understand completely why that point in time was being spent. Now ask yourself "Is there any way to avoid doing this, at least some of the time?" Now, don't act on that right away. Take a few more pauses and study each one the same way.
Now, if you saw such a thing you could avoid doing, and you saw it on more than just one sample, then you should fix it, and you will see a substantial speedup, guaranteed. Now comes the good news: If you do it all again, you will see that you've exposed something else, that can also give you a speedup. This continues until it stops, and then your code is about as nearly optimal as you can make it. Regarding the picture you posted, I've explained many many times why that does not work.
If you do this, you can find anything profilers can find, and plenty that they can't.
The reason is very simple - it comes down to describing things.
What is inclusive time percent of a function? It is the fraction of call stack samples containing that function.
What is self time percent of a function? It is the fraction of call stack samples containing that function at the end.
What is inclusive time percent of a line of code (as opposed to a function)? It is the fraction of call stack samples containing that line of code.
If you look at a call graph, what is the time percent of a link in the graph between functions A and B? It is the fraction of call stack samples in which A is directly calling B.
What is CPU time? It is the time you get if you ignore any samples taken during I/O, sleep, or any other such blocking?
So, if you are examining stack samples yourself, you can locate anything a profiler can locate, just by looking.
You can also locate things that the profiler cannot, such as:
Seeing that a large fraction of time is spent allocating memory for objects that a short time later are simply deleted.
Seeing that a function is being called multiple times with the same arguments, only because the programmer was too lazy to declare a variable to remember the prior result.
Seeing in a 20-level stack sample that a seemingly innocuous function was being called at the 10th level, that the programmer never imagined would be doing file I/O at the 20th level for some obscure reason that its writer couldn't rule out, but you know is not necessary.
Seeing that there are a dozen different functions all doing the same thing but they are different functions because their owner classes have been templated.
Seeing that there is a frequent pattern of function P calling something but then calling R, where P is called from lots of different places, and R calls down to lots of different places.
You can easily see any of these things, and more, just by examining the samples yourself.
Now, the average number of samples it takes to see them depends on how big they are.
If something takes 50% of time, the average number of samples needed to see it twice is 2/0.5 = 4 samples, so if you take 10 samples you are sure to see it.
Suppose there was another thing taking 25% of time.
Now after fixing the first problem and cutting the time in half, the second one takes 50%, not 25%, so it, too, is easy to find.
This is how fixing one speedup exposes the next one.
But as soon as you fail to find a speedup that's really there, the whole process stops, because you stop exposing the ones that are initially small but become really important when the bigger ones are removed.
Profilers give you precise measurements, but what are they measurements of?
(Actually, that precision is fake. All those measurements have standard errors, which you are not shown.)
What are they measurements of? Only very simple stuff, actually.
There's no way they can recognize the kind of stuff you can recognize, since you know the code.
I have had academic profiler fans insist to me that any problem you can find, you can find with a profiler, but that is not a theorem.
There is no justification for it at all, theoretical or practical.
There are plenty of problems that can escape from profilers.
It's a case of "out of sight - out of mind".
"Gee, I ran the profiler on my code, but I couldn't see any bottlenecks, so I guess there aren't any."
If you're serious about performance, you've got to do better than that.

Pong Paddle. Need to carry through the bottom value of count to the top the next time it is initialized

public void update(){
/*
* Purpose: Called each frame update (i.e. 30 times a second)
* Preconditions: None
* Postconditions: return nothing
*/
int count = 0 ;
int x = 0;
if (checkPaddle() == true){
count++;
}
if (count % 2 == 0) {
x = -7;
}
else {
x = 7;}
paddleLocation.y= paddleLocation.y + x;
}//end update
I want the count that is on the bottom to be the initial value at the top of the method. I can't wrap my head around how to do this.

I suppose you could just make the count a member variable and then you could remove the line int count = 0; to prevent the count from reseting during each update:
int count = 0; // Declare it here or in your constructor
public void update() {
int x = 0;
if (checkPaddle() == true) {
count++;
}
if (count % 2 == 0) {
x = -7;
} else {
x = 7;
}
paddleLocation.y = paddleLocation.y + x;
}

Aye, I think you want to make count a private field for this.
On an unrelated note; there is some room for improvement in your code. I would personally get rid of all the empty lines, they take up screenspace. Also, you named your change variable x, which is kinda ambiguous. Since you are using y to denote the y position of the paddle, one might think you mean the x-position for x, while in fact you mean the deltaY. (Change in y-pos).
Lastly, checkPaddle() already returns a boolean value, you don't need to check if it equals true. It looks convoluted.

Program using loops and random generator (beginning java)

A drunkard in a grid of streets randomly picks one of four directions and stumbles to the next intersection, then again randomly picks one of four directions, and so on. You might think that on average the drunkard doesn't move very far because the choices cancel each other out, but that is not the case. Represent locations as integer pairs (x,y). Implement the drunkard's walk over 100 intersections, starting at (0,0) and print the ending location
Can anyone help? I'm completely lost with using random generators and loops in the same program
Below is what I have. It complies fine but doesn't print anything and I'm not sure if I got the random 100 intersection thing right
import java.util.*;
class Drunkard {
int x, y;
Drunkard(int x, int y) {
this.x = x;
this.y = y;
}
void moveNorth() {
this.y -= 1;
}
void moveEast() {
this.x += 1;
}
void report() {
System.out.println("Hiccup: " + x + ", " + y);
}
}
class Four {
public static void main(String[] args) {
Random generator = new Random();
Drunkard drunkard = new Drunkard(100, 100);
int direction;
for (int i = 0; i < 100; i++) {
direction = Math.abs(generator.nextInt()) % 4;
if (direction == 0) { // N
drunkard.moveNorth();
} else if (direction == 1) { // E
drunkard.moveEast();
} else if (direction == 2) { // S
System.out.println("Should move South.");
} else if (direction == 3) { // W
System.out.println("Should move West.");
} else {
System.out.println("Impossible!");
}
System.out.drunkard.report();
}
}
}

your program will be:
initialization
loop: for 1 to 100, do:
i = random()
if i<=0.25 : go north
if i>0.25 and i<=0.5 : go south
if i>0.5 and i<= 0.75 : go east
if i>0.75 and i<= 1 : go west
end loop
show final point.

I see a variety of problems:
You are initializing your Drunkard's position to 100,100. The assignment said to initialize to 0,0.
System.out.drunkard.report() absolutely does not compile. Just call drunkard.report().
The instructions say to print the final location, so you need to move the call to drunkard.report() down one line, so that it is outside of the for loop.
You haven't written methods for moveSouth or moveWest. Write them and add calls to them in the appropriate place.
The class Four needs to be public in order to run it directly.
Good Java programming practices say that every class should be in its own file, but this probably goes against what your instructor asked you to do.
But, I don't think that's your problem. I think there's a problem with how/where you're trying to run the program. You say it compiles fine but doesn't print any output. You know that after it compiles there is another step to run the program, right?
To be clear, here's what you should be doing. At a command line, make sure you are in the directory where your .java file lives. I'm going to assume it's called Four.java. Type the following, hitting enter after each line. (Don't type the $ prompt)
$ javac *.java
$ java Four
I copied the code you posted above, fixed the problems I highlighted, and followed my own instructions above; it works perfectly.

You can use
int direction = (new Random()).nextInt(4);
And use this direction variable to determine where he walks to. I would use recursion in this case instead of a loop.

This starts at 0,0. Generates a random number to determine location and updates the location.
Not sure about the way you are generating the random number, this seems to work well for me.
Point currentLocation = new Point();
currentLocation.setLocation(0, 0);
Point newLocation = new Point(0,0);
Random random = new Random();
//make 100 moves
for(int i=0; i<100; i++)
{
int k = random.nextInt(4);
if(k == 0)
{
//use your drunkard method here
newLocation.setLocation(currentLocation.getX(), currentLocation.getY() + 5);
}
else if (k == 1)
{
//go south
newLocation.setLocation(currentLocation.getX(), currentLocation.getY() - 5);
}
else if (k == 2)
{
//go east
newLocation.setLocation(currentLocation.getX() + 5, currentLocation.getY());
}
else if(k == 3)
{
//go west
newLocation.setLocation(currentLocation.getX() - 5, currentLocation.getY());
}
currentLocation.setLocation(newLocation);
}
System.out.println(currentLocation);
}

You're not implementing your random generator to its full extent.
Random generator = new Random();
int direction = generator.nextInt(4); // This will return a random int
// between 0 and 3
Some other useful tricks when using Random() are as follows:
int i = generator.nextInt(4)+2; // This will return a random int
// between 2 and 5
I highly recommend you check out this if you'd really like to learn all of the neat tricks that you can do using the Random Class.

All i did for this is create a loop that generated a random number between -1 and 1, and summed the values 100 times. Do that for x and for y.
int x = 0;
int y = 0;
//intial = (0,0)
//North = (0, 1)
//South = (0, -1)
//East = (1, 0)
//West = (-1, 0)
for(int i = 0; i < 100; i++)
{
x += (int) (Math.random() * 3) + (-1);
y += (int) (Math.random() * 3) + (-1);
}
System.out.printf("The Drunkard is now located at: (%d, %d)", x, y);