Multi-dimensional arrays Java, as with most languages, supports multi-dimensional arrays - 1-dimensional, 2-dimensional, 3-dimensional, ... This discusses 2-dimensional arrays, but the same principles apply to higher dimensions. 2-dimensional arrays 2-dimensional arrays are usually represented in a row-column approach on paper, and the terms "rows" and "columns" are used in computing. Arrays of arrays There are two ways to implement 2-dimensional arrays. Many languages reserve a block of memory large enough to hold all elements of the full, rectangular, array (number of rows times number of columns times the element size). Java doesn't do this. Instead Java builds multi-dimensional arrays from many one-dimensional arrays, the so-called "arrays of arrays" approach. [C++ supports both styles.] There are a couple of interesting consequences of this: Rows may be different sizes. Also, each row is an object (an array) that can be used independently. Declaration Declare a 2-dimensional array as follows: Code: int[][] a2; // Declares, but doesn't allocate, 2-dim array. Allocation As with all arrays, the new keyword must be used to allocate memory for an array. For example, Code: int[][] a2 = new int[10][5]; This allocates an int array with 10 rows and 5 columns. As with all objects, the values are initialized to zero (unlike local variables which are uninitialized). This actually allocates 6 objects: a one-dimensional array of 5 elements for each of the rows, and a one-dimensional array of ten elements, with each element pointing to the appropriate row array. Processing 2-dimensional arrays Often 2-dimensional arrays are processed with nested for loops. Notice in the following example how the rows are handled as separate objects. For example, Code: int[][] a2 = new int[10][5]; // print array in rectangular form for (int r=0; r<a2.length; r++) { for (int c=0; c<a2[r].length; c++) { System.out.print(" " + a2[r][c]); } System.out.println(""); } Uneven rows One consequence of arrays of arrays is that each row can be a different size ("ragged" arrays). For example, we could create a lower triangular array, allocating each row "by hand" as follows. Code: int[][] tri; tri = new int[10][]; // allocate array of rows for (int r=0; r<tri.length; r++) { tri[r] = new int[r+1]; } // print the triangular array (same as above really) for (int r=0; r<tri.length; r++) { for (int c=0; c<tri[r].length; c++) { System.out.print(" " + tri[r][c]); } System.out.println(""); }
hi pradeep! how about if the user will input student information? Label(row 0) Lastname firstname address dou abc malaysia There are method() 1.Assign name 2.Display name 3.Sort name in ascending 4.Search name how to do this pradeep pls........
We will use a multi-dimensional array. Code: String[][] Data; //Assign the values, do it either dynamically or statically //For first fow Data[0][0] = "S"; //lastname Data[0][1] = "Pradeep"; //firstname Data[0][2] = "Kolkata"; //location //Second row Data[1][0] = "Bhimani"; //lastname Data[1][1] = "Shabbir"; //firstname Data[1][2] = "Kolkata"; //location //Add as many rows you want //printing System.out.print("Lastname\tFirstname\tLocation\n"); for(i=0;i<2;i++) { for(j=0;j<3;j++) { System.out.print(Data[i][j]+"\t"); } //move to new line System.out.print("\n"); } This should do the work for you.
thank you pradeep!!! how about sorting and searching? do you have any tutorial in two dimensional array? thanks.....
You can use simple sorting algorithms like Bubble Sort,Selection Sort to sort the array data. Multi-dimensional array concepts can be applied to two-dimensional arrays. You are free to ask any specific questions you have about two-dimensional arrays.
Pradeep please reply soon we have to complete our project and we are stuck only due to this sorting code.......
Can some one help a novice I am kinda teaching myself java and got stuck trying to create a a program to translate 10 words bi-directional from english to spaniah, using two different String Arrays one consist of english words and one consist of spanish words. Can someone help this novice out? import java.io.*;//tell Java we are using java.io libary. import java.util.*;//Java utility package also for Scanner class public class transWords //Naming the program. { public static void main(String[ ]args)throws Exception { //This set-up allow for user to input using keyboard. Scanner input= new Scanner(System.in); //Declaring Array String. String[]englishTrans={"color","white","blue","green","black","purple",}; //Declaring Array String. String[]spanishTrans={"en color","blanco","azul","verde","negro","purpúreo",};
hi Pradeep, For sorting a 1D array we used the simply Bubble sort aLgorithm which worked perfectly fine...but we cant write the code 4 the 2D array as we had written earlier.... thx... Shilpa
sir, i want to show a 2D array corresponding to a .jpg/.gif/.png image file in a separate window. suppose i have... class Image { protected int width,height; // 'samples' stores the image pixel values. protected int[][] samples; // Constructor: Reads the image from the // specified file name. public Image(String filename) throws Exception { read(filename); } // Returns the pixel width of the image. public int getWidth() { return width; } // Returns the pixel height of the image. public int getHeight() { return height; } // Reads the image from the specified file // name into the 'samples' array. Throws an // exception if the image is stored in an // unsupported file format (currently only // .GIF, .JPG, and .PNG are supported by Sun). public void read(String filename) throws Exception { // Extract the file name suffix... ....... ........... ............. from the startup java file like.. import java.awt.*; import javax.imageio.*; class TestImage { public static void main(String args[]) throws Exception { // Create a frame to display the image. Frame frame = new Frame("Test Image"); frame.setSize(1024,768); frame.setVisible(true); Graphics gc = frame.getGraphics(); try { // Read the image from the file. Image img = new Image("Horse.jpg"); ......... I want to access the int [][] samples array then want to disply this array values in a separate windo or applet..How to approach......
i'm trying to create a method that adds an element in an existing string array. Kind of like the arraylist "add()" method. so far, i have this String[] addToArray(String[] strArray1, String s) { return strArray1+s; } but this doesnt work... why? :worried:
Hi! I need to compare 2 words in a given name and see if any part of the name in index [0] (first name and/or surname) matches the rest of the names. For instance, robert smith | robert mathews | john robert | john roberts Basically, only the first and lastname in the first index ("robert smith") needs to be compared with rest of the first and the last names. ' How do I go about this? I'm successful in comparing just 1 word. eg: robert|RoBERT|smith boolean result1= choiceKeys[0].equalsIgnoreCase (choiceKeys[i+1]); What should I do when I have 2 words? Thanks in advance, -new2Java
Hai I am inteested in adding elements to 2D array. So i do like this i have always one input as prod id ; where i get from parameter then the for loop Code: [COLOR=navy][B]int[/B][/COLOR] n = productsid; [COLOR=navy][B]for[/B][/COLOR]( row=0;row<10;row++) [COLOR=navy]{[/COLOR] year2007[n][row] = ([COLOR=navy][B]float[/B][/COLOR]) tot; [COLOR=navy]}[/COLOR] but when i display my array i dont get the prod id?? what ican do ??