J2SE _ Array

Array Overview

Declaration of a one-dimensional array

、

creation of Array objects

element is an array of reference data types

array Initialization (1)

array Initialization (2)

default initialization of array elements

references to array elements

 Public classTestargs { Public Static voidMain (string[] args) {/*for (int i=0; i<args.length; i++) {System.out.println (args[i]);              } System.out.println ("Usage:java Test \" n1\ "\" Op\ "\" n2\ ""); */    if(args.length<3) {System.out.println ("Usage:java Test \" n1\ "\" Op\ "\" N2\ ""); System.exit (-1); }     DoubleD1 = double.parsedouble (args[0]); DoubleD2 = double.parsedouble (args[2]); Doubled = 0; if(Args[1].equals ("+")) d = d1+D2; Else if(Args[1].equals ("-")) d = d1-D2; Else if(Args[1].equals ("X")) d = d1*D2; Else if(Args[1].equals ("/")) d = d1/D2; Else{System.out.println ("Error operator!"); System.exit (-1);    } System.out.println (d); }}

Testargs.java

 Public classtestarray{ Public Static voidMain (string[] args) {int[] A =New int[Args.length];  for(inti=0; i<args.length; i++) {A[i]=Integer.parseint (Args[i]); } System.out.print ("Before sorting:");        Print (a); System.out.print ("\ n Sort after:"); //Bubble_sort (a);Selectionsort (a);    Print (a); }    //Select Sort    Private Static voidSelectionsort (int[] a) {         for(inti=0;i<a.length;i++){             for(intj=i+1; j<a.length;j++){                if(a[i]>A[j]) {                    intTemp=0; Temp=A[i]; A[i]=A[j]; A[J]=temp; }            }        }    }    //Select Sort Improvements    Private Static voidSelectionsort (int[] a) {        intk, temp;  for(inti=0;i<a.length;i++) {k=i;  for(intj=k+1; j<a.length;j++){                if(a[j]>A[k]) {k=J; }            }            if(k! =i) {Temp=A[i]; A[i]=A[k]; A[K]=temp; }        }    }    //Bubble Sort    Private Static voidBubble_sort (int[] a) {         for(inti=0;i<a.length-1;i++){             for(intj=0; j<a.length-i-1;j++){                if(A[j] > a[j+1]){                    inttemp = 0; Temp=A[j]; A[J]= A[j+1]; A[j+1] =temp; }            }        }    }    //Print one-dimensional array    Private Static voidPrintint[] a) {         for(inti=0; i<a.length;i++) {System.out.print (A[i]+" "); }    }}

Sort.java

Classroom Exercises

 Public classTestdatesort { Public Static voidMain (string[] args) {date[] days=NewDate[5]; days[0] =NewDate (2006, 5, 4); days[1] =NewDate (2006, 7, 4); days[2] =NewDate (2008, 5, 4); days[3] =NewDate (2004, 5, 9); days[4] =NewDate (2004, 5, 4); Date D=NewDate (2006, 7, 4); String Str=string.valueof (d); //str = d.tostring ();Bubblesort (days);  for(inti=0; i<days.length; i++) {System.out.println (days[i]);    } System.out.println (BinarySearch (days, D)); }          Public Staticdate[] Bubblesort (date[] a) {intLen =a.length;  for(inti = len-1;i>=1;i--){             for(intj = 0;j<=i-1;j++){                if(A[j].compare (a[j+1]) > 0) {Date temp=A[j]; A[J]=a[j+1]; A[j+1]=temp; }            }        }        returnA; }         Public Static intBinarySearch (date[] days, Date d) {if(days.length==0)return-1; intstartpos = 0; intEndpos = days.length-1; intm = (startpos + endpos)/2;  while(Startpos <=endpos) {          if(D.compare (days[m]) = = 0)returnm; if(D.compare (days[m]) > 0) {startpos= m + 1; }          if(D.compare (days[m]) < 0) {Endpos= M-1; } m= (startpos + endpos)/2; }        return-1; }}classDate {intYear , month, day; Date (intYintMintd) { year= y; month = m; Day =D; }     Public intCompare (date date) {returnYear > Date.year? 1: Year< date.year? -1: Month> Date.month? 1: Month< Date.month? -1: Day> Date.day? 1: Day< Date.day? -1:0; }     PublicString toString () {return"Year:Month:Day--" + year + "-" + Month + "-" +Day ; }}

Testdatesort.java

Add 3 back 1

 Public classCount3quit { Public Static voidMain (string[] args) {Boolean[] arr =New Boolean[500];  for(inti=0; i<arr.length; i++) {Arr[i]=true; }                intLeftcount =arr.length; intCountnum = 0; intindex = 0;  while(Leftcount > 1) {            if(Arr[index] = =true) {Countnum++; if(Countnum = = 3) {Countnum= 0; Arr[index]=false; Leftcount--; }} Index++; if(Index = =arr.length) {index= 0; }        }                 for(inti=0; i<arr.length; i++) {            if(Arr[i] = =true) {System.out.println (i); }        }    }}

Count3quit.java

J2SE _ Array