2015-07-27

int farray[]=new int[3];//int specify the type of the element,[] indicate that 'farray' is an array        //*********************************************************************************        String [] stringArray=new String[3];//array can be also defined this way        stringArray[0]="this is my reburn";//the elements which don't be assigned value manually will be null        //****************************************************************        int intArray[];        intArray=new int[3];//this is another way to define an array:declare then assign space        //**********************************************************************        //***************************initialization********************************************        int f2array[]={1,2,3};        String [] string2Array={"string1","string2"};//initialize while declaring,this way is also known as static initailization        int f3array[]=new int[5];        f3array[0]=1;        f3array[2]=4;//***************** it will be 0 where you didnot assign value        Scanner s=new Scanner(System.in);//receive the data from console        while(s.hasNext()){            String line=s.nextLine();            if (line.equals("exit")) {                break;            }            if (line=="exit") {//cannot compare the content of two strings by '==',as for basic data type '==' will compare their values,but for complex the comparasion is address                System.out.println("you choose to exit");            }            System.out.println(line=="exit");        }        for (int i=0;i<f3array.length ; i++) {            System.out.println(f3array[i]);        }        String s1="hello";        String s2="hello";        System.out.println(s1.equals(s2));    //*******************************constants in java*****************    In Java,contants are declared by final keywords not const.    System.out.println(NUM);    //*********************************not changable string************cant change the data where string variables refer to*******        String a="hello";    //*****************************************build  string*******************    StringBuilder builder=new StringBuilder();    String b="java";    builder.append(a);    builder.append(b);    b=builder.toString();    System.out.println(b);    //*****************************************scanner*********        System.out.println("what's your name?\n");    Scanner in=new Scanner(System.in);    System.out.println("your name is "+in.nextInt());    //***************************************************console**********        Console cons=System.console();        String username=cons.readLine("what's your name?");        char [] pwd=cons.readPassword("password:");    //****************************************formatting output*******        double x=100000/3;        System.out.printf("%0f",x);    //**************************************************************