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This website is underconstruction. Author: Martin Sykes Challenge: I have challenged myself to 1 article per day, and framework improvements! Enjoy Challenge end: unknown

Arrays

We have covered a variables, an arrays is multiple variables with the same name, how could this be useful? Imagine you wanted to store the names of everyone who uses your program in memory...

Code:
String name0="martin";
String name1="joe";
String name2="moe";
String name3="";
String name4="";

This way is infeicient you cannot loop through the names their is no way to chance a variable in code, without an if statement eg, adding a name:

Code:
String tmpname="john";
if(name0.compareTo("")==0){

name0=tmpname;

} else if(name1.compareTo("")==0){

name1=tmpname;

} else if(name2.compareTo("")==0){

name2=tmpname;

} else if(name3.compareTo("")==0){

name3=tmpname;

} else if(name4.compareTo("")==0){

name4=tmpname;

} else{

System.out.println("memory full");

}

Their has to be a better way! and ofcourse their is, Arrays!
The sample below does the exact same as above but with Arrays.
Create a new project named 'namecheck' with a class named 'namecheck'
We will be optimising (improving) this in the next tutorial.

Code:
public class namecheck {

public static void main(String[] args) {

// Array declaration, like the sample above 5 different names 0,1,2,3,4 (NOT 5)
String name[] = new String[5];
// setting values
name[0]="martin";
name[1]="joe";
name[2]="moe";
name[3]="";
name[4]="";

String tmpname="john";
int i=0, set_index=-1;

// 0
if(name[i].compareTo("")==0){

set_index=i;

}
// 1
i++;
if(name[i].compareTo("")==0){

set_index=i;

}
// 2
i++;
if(name[i].compareTo("")==0){

set_index=i;

}
// 3
i++;
if(name[i].compareTo("")==0){

set_index=i;

}
// 4
i++;
if(name[i].compareTo("")==0){

set_index=i;

}

if(set_index==-1){

System.out.println("memory full");

} else{

name[set_index]=tmpname

}

}

}

Once again I have shown you a 'better' way and increased the size of the code, I haven't covered loops yet which I am covering in the next tutorial, for now note that with an Array the code repeats itself letter for letter 5 times. Since it allowed me to create an integer 'i' and increment it (add 1) 5 times doing the same check with the same code.

Without knowing loops I cannot go into any more details. Please read the next tutorial

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