Java Exam Cheat Sheet

public class HelloWorld{
    //Main method must take String[] args
    public static void main(String[] args){
        //Main functionality here
    }
}

public class ObjectName{

    //variables that are private to this object
    private *type *variableName;
   
    //Constructor gets called when new method is created --> Multiple constructors 
    //can exist
    public ObjectName(*parameters){
        //Whatever happens in constructor
    }
}

IntegerStack intStack = new IntegerStack();

//Add an element to the stack
intStack.push(int);

//Removing the top element from the stack
intStack.pop();

//checking if empty
intStack.isEmpty();

P = integer array (n+1, V+1)
for(v = 0 ... V)
P(0,v) = 0;
for (i = 1 ... n)
for (v = 0 ... V)
if (volumes(i-1) <= v)
P(i,v) = max(profit(i-1) + P(i-1,v-volumes(i-1)),
P(i-1,v));
else
P(i,v) = P(i-1,v)
return P(n,V);

**If Statem­ent**
if ( expre­ssion ) {
 ­ ­st­ate­ments 
} else if ( expre­ssion ) {
 ­ ­st­ate­ments
} else {
 ­ ­st­ate­ments
}

**While Loop**
while ( expre­ssion ) {
 ­ ­st­ate­ments
}

**Do-While Loop**
do {
 ­ ­st­ate­ments
} while ( expre­ssion );

**For Loop**
for ( int i = 0; i < max; ++i) {
 ­ ­st­ate­ments
}

**For Each Loop**
for ( var : colle­ction ) {
 ­ ­st­ate­ments
}

**Switch Statem­ent**
switch ( expre­ssion ) {
 ­ case value:
 ­ ­ ­ ­st­ate­ments
 ­ ­ ­ ­break;
 ­ case value2:
 ­ ­ ­ ­st­ate­ments
 ­ ­ ­ ­break;
 ­ ­def­ault:
 ­ ­ ­ ­st­ate­ments
}

**Exce­ption Handling**
try {
 ­ ­sta­tem­ents;
} catch (Exce­pti­onType e1) {
 ­ ­sta­tem­ents;
} catch (Exception e2) {
 ­ ­cat­ch-all statem­ents;
} finally {
 ­ ­sta­tem­ents;
}

Insertion Sort:
for (i = 1 ... n-1)
for (j = i ... 1)
if (a(j-1) > a(j))
swap(a(j-1),a(j))
else break;

*type[] *arrayName = new *type[*length]
E.g.
boolean[] visitedNode = new boolean[this.numberOfNodes];

Queue<type> q = new Queue<type>();

//put element in queue
q.enqueue(e);

//remove element in queue
q.dequeue();

//check if empty
q.isEmpty();

//check size
q.length(); or q.size();

public static int GCD (int m, int n){
    int temp;
    while (n%m != 0){
      temp = m;
      m = n%m;
      n = temp;
      if (m==0) return 1;
    }
    return m;
  }