How to print all values of Vector[]

Question

I have a Vector of Object[] type that stores my data. How to print all it's objects ?

The code:

private static Vector<Object[]> vector = new Vector<Object[]>();


int event=0;
for(int i=0; i<10; i++){
    vector.add( this.addToObject(System.currentTimeMillis(), event , "String") );
    event++;    
}

private Object[] addToObject(long t, int i,String s ){
    Object[] o = new Object[4];
    o[3] = s;
    o[2] = i;
    o[1] = "00000";
    o[0] = t;
    return o;
}

printing

public static void main(String[]args){
    main m = new Main();

    for(int i=0; i< m.vector.size(); i++){

    }

}

And I'd like to get sth like this :

1202393057117 1 OOOOO String
1202393057117 2 OOOOO String
1202393057118 3 OOOOO String
1202393057118 4 OOOOO String
1202393057118 5 OOOOO String

Answer 1

Inside your printing for loop:

Object[] objs = vector.get(i);
for (Object o : objs) {
    System.out.print(o + " ");
}
System.out.println()

Answer 2

Arrays.deepToString(vector.get(i));

Or print them manually, as Lauri Lehtinen suggests.

Answer 3

Within the loop:

Object[] o = m.vector.get(i);
System.out.printf("%d %d %s %s\n", o[0], o[2], o[1], o[3]);

Answer 4

Joshua Bloch, in Effective Java, suggests using the for-each loop whenever possible:

for (Object[] array : vector) {
    for (Object obj : array) {
        System.out.println(obj);
    }
}

But since you are using the Object[] with fixed size of 4, with pre-known set of properties, it is highly advisable to create a new class:

class DataHolder {
    private someProperty;
    private someOtherProperty;
    ... + setters and getters
}

And instead of array[2] = something, you will have dataHolder.setSomeProperty(something) - far more readable and maintainable.

The next step is to override toString() (again as advised by Bloch) and implement it to print the whole internal state of the object.

And then the loop will look like this:

for (DataHolder dataHolder : vector) {
    System.out.println(dataHolder);
}