JAVA
Lesson 4: Loops
While Loops
public void alarm() {
boolen on = checkAlarm();
if(on){
beep();
on=checkAlarm();
}
if(on){
beep();
on=checkAlarm();
}
if(on){
beep();
on=checkAlarm();
}
---//until someone turn off the alarm
}
/*Using While Loop*/
public void alarm(){
boolean on = checkAlarm();
while(on){
beep();
on = checkalarm();
}
}
String googol = '1';
int len = googol.length();
while(len <101){
googol = googol + "0";
len= googol.length();
}
public void raiseAlarm(int numOfWarnings) {
int i = 1;
while(i <= numOfWarnings) {
System.out.println("warning");
i++;
}
}
For Loops
public void raiseAlarm(int numOfWarnings) {
for(int i = 1; i<= numOfWarnings; i++){
System.out.println("Warning #" + i);
}
}
/*
Adds the numbers 15+116+ .. + 20
@return the total sum
*/
public int addNmbers() {
int sum = 0;
for(int i = 15; i <= 20; i++){
sum = sum + i;
}
return sum;
}
/* Counting Down */
for(int i = 3; i >= 1; i--){
System.out.println(i);
}
i = i+1 == i++
i = i + 5 == i += 5
/*Using break;*/
public int martingale() {
int money = 1000;
int target = 1200;
int bet = 10;
while (money > bet) {
boolean win = play();
if (win) {
money += bet;
bet = 10;
} else {
money -= bet;
bet *= 2;
}
// Add the break here:
if(money >= target)
break;
}
return money;
}
Arrays
- cell : value
- index
int [] numbers = {12,1,777,3,4,0,0,121,1,-4,0,-100,2};
System.out.println(number[0]); // answer is 12
System.out.println()
String [] nesOutlet = {"KBS", "MBC", "SBS", "TVN", "JTBC", "BBC", "FOX", "CNN", "ABC"};
double lucky = Math.random();
//Multiply by 10 to get a fractional number between 0 - 10
luckey *= 10;
//cast to integer to get an integer number between 0 - 9
int luckyIndex = int lucky;
System.out.print(newOutlet[luckyIndex]);
Arrays and Loops
prublic double calculateAverage(double [] temperatures) {
int size = temperatures.length;
double total = 0;
for(int i=0; i<size; i++){
total += temperatures[i];
}
double average = total.size;
return average;
}
/* Array Search - find longest name*/
public String findLongestName(String [] names){
int size = names.length;
String longestNames = names[0];
for(int i=0; i<size; i++){
if(names[i].length() > longestNames.length()){
longestNames = names[i];
}
}
return longestNames;
}
2D arrays
public static double englishAverage(int [][] grades, int student) {
int subjects = grades.length;
int total = 0;
for(int i=0;i<subjects;i++) {
total = grade[i][student];
}
double average = total/(double)subjects;
return average;
}
I’m studing a “Java Programming Basics” @Udacity.