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Thread: Java Basic - explanation of for loops

  1. #1
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    Default Java Basic - explanation of for loops

    class GraphPanel extends Panel
    //GraphPanel is being defined as subclass of Panel
        implements Runnable, MouseListener, MouseMotionListener { //runnable
    //using an interface, allows q method from ore than one superclass
        Graph graph; //attribute  or variable
        int nnodes; //attribute  or variable, primitive data type
        Node nodes[] = new Node[100];
        int nedges; //attribute  or variable intial value
        Edge edges[] = new Edge[200];
        Thread relaxer;
        GraphPanel(Graph graph) {
        this.graph = graph;
        int findNode(String lbl) {
        for (int i = 0 ; i < nnodes ; i++) {
    //statement executes if  test returns true

    Just in regards to the for loop, not sure what the i < nnodes is testing. Is it comparing i to the individual value of each nnodes variable, or is it comparing to see whether i is less than the length of nnodes array?
    Last edited by helloworld922; May 24th, 2011 at 06:03 PM.

  2. #2
    Super Moderator helloworld922's Avatar
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    Default Re: Java Basic - explanation of for loops

    nnodes is an integer variable. It's comparing i to the integer value of nnodes.

  3. #3
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    Default Re: Java Basic - explanation of for loops

    The "for" statement does 3 things. First you declare/intantiate something. Then you declare a condition. Finally, you declare an action. In your example, you create an integer 'i', check that the value of 'i' is less than the value of 'nnodes', and if so, add 1 to the value of 'i'. The loop is repeated as long as these conditions are met.

    for(int i=0; i< nnodes; i++)
    //Put code here that you want to be executed every time the conditions of the loop are met.

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