Why println doesn't show my array

Question

public static void displayArray(int tab[]){
    int i;
    String choix; // choice


    System.out.println("\n you want to see the values you entred from first position or last ?");
    System.out.println("tape "P" for first , and"D" for last);
    choix=sc1.nextLine(); // sc1 for nextLine , sc for nextInt to avoid buffering problems .

    if(choix=="p"||choix=="P") 
    {    for(i=0;i<k;i++)      //k is the maximum of the array(max index)
        System.out.println("T["+i+"]= "+tab[i]); // why this instruction doesn't work ??

    }

    if(choix=="D"||choix=="d")
    {for(i=k-1;i>=0;i--)
        System.out.println("T["+i+"]= "+tab[i]);// this one too doesn't work

    }}      


     public static void main(String[] args) {
        // TODO Auto-generated method;stub
         int tab[]=new int[4];

         System.out.println(readIntArray(tab));
         displayArray(tab);
    }    
}

I don't understand why displayArray doesn't work, System.out.println should print my array after checking the condition but it doesn't work.

Answer 1

I assume it's in Java. When you compare string use

string.equals(String)

Instead of ==

It should work with :

if(choix.equals("p") || choix.equals("P"))
if(choix.equals("D") || choix.equals("d"))

Answer 2

When you are comparing Object s, == not only compares their value, but compares the given objects as well. For example:

String a = "foo";
String b = "foo";
a == b; //false
a.equals(b); //true

since equals compares whether the objects are similar, == compares whether the objects are the same. Also, if you are using quotes inside a String , you need to escape them with \\" , since if you use just use " then you are closing the String , resulting in errors. So, you should do something like this:

public static void displayArray(int tab[]){
    int i;
    String choix; // choice


    System.out.println("\n you want to see the values you entred from first position or last ?");
    System.out.println("tape \"P\" for first , and\"D\" for last);
    choix=sc1.nextLine(); // sc1 for nextLine , sc for nextInt to avoid buffering problems .

    if(choix.equals("p")||choix.equals("P")) 
    {    for(i=0;i<k;i++)      //k is the maximum of the array(max index)
        System.out.println("T["+i+"]= "+tab[i]); // why this instruction doesn't work ?? 
        //Your code did not even reach this point due to using unescape quotes inside a String and incorrect comparisons in your if

    }

    if(choix.equals("D")||choix.equals("d"))
    {for(i=k-1;i>=0;i--)
        System.out.println("T["+i+"]= "+tab[i]);// this one too doesn't work
        //The reason is the very same as above

    }}      


     public static void main(String[] args) {
        // TODO Auto-generated method;stub
         int tab[]=new int[4];

         System.out.println(readIntArray(tab));
         displayArray(tab);
    }    
}

Also, you need to structure your code, since, as it is, it is difficult to read it.