How To Find Highest Number In Array Java

Coffee Notes

Array Instance - Maximum

To detect the maximum value in an array:

1. Assign the kickoff (or any) array element to the variable that will hold the maximum value.
2. Loop through the remaining assortment elements, starting at the second element (subscript 1). When a larger value is found, that becomes the new maximum.

//===================================================== max public static int max(int[] t) {     int maximum = t[0];   // start with the showtime value     for (int i=1; i<t.length; i++) {         if (t[i] > maximum) {             maximum = t[i];   // new maximum         }     }     return maximum; }//stop method max        

To make this piece of work with object types (eg String), yous will accept to change the type declarations of grade, but you lot will also have to change the comparing to use .compareTo(), which must be defined for that object type.

The minimum can be institute by the same algorithm, simply inverting the exam. It'south also easy to add a test for the minimum to this loop so that both the maximum and minimum are determined inside the aforementioned loop.

There is one common variation on this -- sometimes it isn't the maximum value that is desired, but the index of the maximum value (eg, so information technology can exist changed).

Mutual error -- starting with the wrong initial value

Choosing the starting time value of an array for the maximum (or minimum) e'er works. However, most student programs start with a fixed value, like cypher. This often appears to work because almost test information values are positive. However, it'southward very fragile, and often wrong. If you lot really demand to start with an initial value in some situation (unlikely), and then use the smallest possible value, Integer.MIN_VALUE as the initial value for the maximum.

Non-full arrays - need additional parameter

This method assumes that all the elements of the assortment should be sorted. When your arrays may non be full (a common state of affairs), the method should have an additional parameter which is the number of elements currently in it. Encounter the programming exercises below.

Mistake possibility - no elements

A minor problem with this algorithm is what to do if in that location are absolutely no elements in the assortment -- t.length is zero. There is no maximum value.

Exceptions. This will produce an error, ArrayIndexOutOfBounds, when nosotros endeavour to get that first element. 1 solution is to let this exception to be thrown, which is easiest because it requires no programming. Some other would be to throw IllegalArgumentException with a more than meaningful message. This would be more useful if y'all expected this fault to occur very frequently, simply probably isn't worth the attempt. Zero-length arrays are ordinarily produced as the issue and so an error earlier in the code, and they are encountered occasionally in the process of debugging.

Return index. Another way to bargain with this is to change the way the method works to return the index, and when there are no elements return an impossible index (eg, -1). Many programmers won't worry about this case because it volition exist incommunicable for their programme. However, you should ever remember nearly the possibility of an empty array.

Return illegal value. There is no illegal value for int, only in that location is for double, Double.NaN (NaN = "Non a Number"), and nix can exist used for object types.

Loop backwards?

Very rarely will you find a programmer who prefers to write loops that get from loftier to low. Of course it makes no divergence in this algorithm, nevertheless, at that place are machines in which that can salve a few nanoseconds. Backwards loops are harder to read so it'south mostly considered antisocial to write them without a proficient reason.

Collections max method

If y'all take an array of objects (non primitives), yous tin can utilise the Collections.max(...) method after making the array look like a List. For case,

          String[] names = . . .;     . . .     Cord highest = Collections.max(Arrays.asList(names));

Exercises

1. Comparison? How would the to a higher place method perform differently if the comparison was inverse from > to >= ?
2. Minimum. If you don't start with a value from the bodily data for the initial minimum of an array of ints, what would be the best initial value to utilise?
3. Index. Write a method, indexOfMaximum, which returns the index of the maximum valued element, not the value.
4. Partially full. A very common state of affairs is for arrays to be only partially full. It but takes a slight modification of the code to write a method that takes an additional parameter, size, that specifies the number of elements in the array that have values.

                 public static int max(int[] t, int size)            

5. Strings. Rewrite the maximum method to piece of work with the String type and so that it will sort without regard to case.
6. ( Advanced) Generic. If the elements of a class are going to be compared, the programmer of the form will have implemented the Comparable interface, which means that the class will accept a compareTo(...) method. You could write the following generic method which will work for all Comparable objects.

                 public static <T extends Comparable<T>> T max(T[] a) {

   Oftentimes the hardest office is writing generic methods is the header, but I've written that for you. At present write the torso of the method.

Source: https://perso.ensta-paris.fr/~diam/java/online/notes-java/data/arrays/arrays-ex-max.html

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