编写一个Java程序，它能产生从0~9的十个数字中随机取出4个不重复的数字组成一个字符串 我刚学JAVA（刚学完数组），有没有好的JAVA题库？要有原...
\u6c42\u7f16\u4e2a\u6570\u5b57\u8f6c\u7801\u7684JAVA\u7a0b\u5e8f\uff0c\u53ea\u67099\u4e2a\u89c4\u5219\uff01package testpractice;
import java.util.Scanner;
public class Test
{
/**
* @param args
*/
public static void main(String[] args)
{
Scanner s = new Scanner(System.in);
int number = 0;
while(number >= 0)
{
System.out.println("\u8bf7\u8f93\u51650~9\u5230\u7684\u6574\u6570\uff1a");
number = s.nextInt();
switch(number)
{
case 0:System.out.println("48");
break;
case 1:System.out.println("c8");
break;
case 2:System.out.println("49");
break;
case 3:System.out.println("c9");
break;
case 4:System.out.println("58");
break;
case 5:System.out.println("d8");
break;
case 6:System.out.println("59");
break;
case 7:System.out.println("d9");
break;
case 8:System.out.println("68");
break;
case 9:System.out.println("e8");
break;
default:System.out.println("\u4f60\u8f93\u5165\u7684\u9519\u8bef\uff01");
}
}
}
}
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*\u5728Linux\u4e0b\u7684\u6743\u9650\uff0c\u5206\u4e3a\u8bfb\u3001\u5199\u3001\u6267\u884c\uff0c\u5206\u522b\u5bf9\u5e94421\uff0c\u90a3\u4e48\u4efb\u610f\u7ed9\u4e00\u4e2a0~7\u7684\u6570\u5b57\uff0c\u8ba1\u7b97\u51fa\u8be5\u6570\u5b57\u5177\u6709\u7684\u6743\u9650\u3002\u73b0\u5b9e\u7ed3\u679c\u3002
\u60a8\u7684\u6743\u9650\u4e3a\uff1a5
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\u57fa\u672c\u529f\u7ec3\u4e60\uff08\u6d41\u7a0b\u63a7\u5236\uff09
\u7ed9\u51fa0~100\u5206\u6210\u7ee9\uff0c\u663e\u793a\u4e3a\u201c\u4f18\u79c0\u201d\uff0890 \u5206\u4ee5\u4e0a\uff09\uff0c\u201c\u826f\u597d\u201d\uff0880~89\uff09\uff0c\u201c\u53ca\u683c\u201d\uff0860~79\uff09
\u201c\u4e0d\u53ca\u683c\u201d\uff0860\u4ee5\u4e0b\uff09
\u6253\u5370\u56fe\u5f62\uff08n\u884c\uff09
*
**
***
****
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*
***
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*********
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\u6253\u53701~100\u6240\u6709\u5947\u6570\u7684\u548c
\u6253\u53701~100\u6240\u6709\u7d20\u6570\u7684\u548c\uff08\u9009\u505a\uff09
*\u6253\u5370\u4e00\u4e2a\u4e8c\u8fdb\u5236\u6570\u8868\u793a\u4e2d1\u7684\u4e2a\u6570\uff08\u9762\u8bd5\u9898\uff09
\u6253\u5370\u4e58\u6cd5\u8868
\u65b9\u6cd5
\u5224\u65ad\u8f93\u5165\u662f\u5426\u5927\u4e8e1500
\u5224\u65ad\u8f93\u5165\u662f\u5426\u4e3a\u5947\u6570
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1600\u4ee5\u4e0b\u4e0d\u4ea4\u7a0e
1601~5000 5%
5001~8000 10%
8001~20000 20%
20000~ 50%
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\u751f\u62103\u4e2a\u5b66\u751f\u5b9e\u4f8b\uff0c\u8c03\u7528\u5b66\u751f\u5b9e\u4f8b\u7684showInfo\u65b9\u6cd5
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\u6253\u5370\u5f53\u524d\u65f6\u95f4\uff0c\u5b66\u4e60\u4f7f\u7528Date\u7c7b\u548cCalendar\u7c7b
\u6253\u537050~100\u968f\u673a\u6570
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public class Util{ public static Boolean isLeapYear(BirthDate b)}
\u751f\u6210\u4e24\u4e2a\u5728\u5e73\u9762\u4e2d\u5706\u7684\u5b9e\u4f8b\uff0c\u5224\u65ad\u4e24\u4e2a\u5706\u662f\u5426\u76f8\u4ea4
\u57fa\u672c\u529f\u7ec3\u4e60\uff082\uff09
\u6c42\u4e24\u4e2a\u6574\u6570\u7684\u8f93\u5165\u7684\u6700\u5927\u503c public int max(int x, inty)
\u6c42\u4e09\u4e2a\u6574\u6570\u7684\u6700\u5927\u503c
\u968f\u5373\u4ea7\u751f\u4e00\u4e2a1800~2200\u5e74\u7684\u968f\u5373\u6570\uff0c\u5e76\u5224\u65ad\u662f\u5426\u4e3a\u95f0\u5e74
* \u7f16\u5199\u4e00\u4e2aJava\u7a0b\u5e8f\uff0c\u5b83\u80fd\u4ea7\u751f\u4ece0~9\u7684\u5341\u4e2a\u6570\u5b57\u4e2d\u968f\u673a\u53d6\u51fa4\u4e2a\u4e0d\u91cd\u590d\u7684\u6570\u5b57\u7ec4\u6210\u4e00\u4e2a\u5b57\u7b26\u4e32\uff0c\u4f8b\u5982\uff1a0123\uff0c3657\uff0c4578
* \u7ed9\u51fa\u4e00\u4e2a\u65b9\u6cd5\uff0c\u5f97\u5230\u81ea\u5df1\u7684\u751f\u65e5\u662f\u661f\u671f\u51e0
\u9012\u5f52
\u6c425\u7684\u9636\u4e58
* \u6c42\u6590\u6ce2\u90a3\u5951\u6570\u5217\u7684\u7b2c10\u9879\uff1a1\uff0c1\uff0c2\uff0c3\uff0c5\uff0c8\uff0c13
\u6c42\u4e24\u4e2a\u6570\u7684\u6700\u5927\u516c\u7ea6\u6570\uff1agcd(a,b) = gcd(b,a mod b)
//public int getMax(int a,int b){if(b == 0) return a; return getMax(b,a%b);}
\u6570\u7ec4
\u521b\u5efa\u957f\u5ea6\u4e3a10\u7684\u6570\u7ec4\uff0c\u6570\u7ec4\u4e2d\u7684\u5143\u7d20\u4e3a\u9012\u589e\u7684\u5947\u6570\u3002\u9996\u9879\u4e3a1\u3002
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\u5199\u51fa\u6570\u7ec4\u6c42\u548c\u65b9\u6cd5\u3002
Public static int sum(int [] arr)
\u627e\u5230\u6570\u7ec4\u4e2d\u6700\u5927\u7684\u6570\u6240\u5728\u7684\u5750\u6807
Public static int max(int [] arr)
\u8ba1\u7b97\u6570\u7ec4\u4e2d\u6700\u5927\u6570\u4e0e\u6700\u5c0f\u6570\u7684\u5dee
Public static int range(int [] arr)
\u5bf9\u6570\u7ec4\u8fdb\u884c\u6d17\u724c\u64cd\u4f5c
\u5199\u4e00\u4e2a\u65b9\u6cd5\uff0c\u6c42\u6570\u7ec4\u7684\u8fde\u63a5
Public static int[] concat(int[] a, int[] b)
\u7406\u89e3\u5bf9\u8c61\u6570\u7ec4\uff0c\u521b\u5efaPoint\u6570\u7ec4\uff0c\u8981\u6c42\u6570\u7ec4\u4e2d\u7684\u6bcf\u4e2a\u70b9\u90fd\u5728\u4e0ex,y\u8f74\u5939\u89d2\u4e3a45\u5ea6\u7684\u76f4\u7ebf\u4e0a\u3002
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\u5b66\u4e60\u7f16\u5199Bubble Sort
\u4f7f\u7528sort\uff0c\u6392\u5e8f\u6570\u7ec4\u540e5\u4e2a\u5143\u7d20
public class test{
public static void main(String[] args){
Random ran = new Random();
StringBuffer sb = new StringBuffer();
int i = 0;
while(i < 4){
int t = ran.nextInt(9);
if(sb.indexOf(String.valueOf(t)) == -1){
sb.append(t);
i++;
}
}
System.out.println(sb.toString());
}
}
import java.util.Random;
public class A
{
public static void main(String[] args)
{
int lng=8;//这里是你要定义的总长度，想多少输多少，但是注意：不能超过随机数 间隔的最大值。
Random r = new Random();
String result = "";
String count =String.valueOf(r.nextInt(9));
while (result.length() != lng)
{
count =String.valueOf(r.nextInt(9));
if (result.contains(count)==false)
result += count;
}
System.out.println(result);
}
}
一楼的写得真不错 sb.indexOf(String.valueOf(t)) == -1
可是你这个int t = ran.nextInt(9); t随机取不到9了哦 呵呵 改为10的话就完美了
下面是我写的 比较笨的方法 帮你调试好了 看下吧
import java.util.Random;
public class P {
public static void main(String[] args) {
Random rand = new Random();
int r1, r2, r3, r4;
flag:
while (true) {
r1 = rand.nextInt(10);
r2 = rand.nextInt(10);
r3 = rand.nextInt(10);
r4 = rand.nextInt(10);
if ((r1 != r2) && (r1 != r3) && (r1 != r4) && (r2 != r3)
&& (r2 != r4) && (r3 != r4)) {
System.out.println(r1 + "" + r2 + "" + r3 + "" + r4);
break;
}
continue flag;
}
}
}
其实一楼写的非常好 那个.indexOf(String.valueOf(t)) == -1 用的相当精彩
我思量着
.indexOf(Integer.toString(t)) == -1 .indexOf(new Integer(t).toString()) == -1
也是可行的
为了展示不同的想法 我写个不同的 当然并不是最好的
import java.util.Random;
public class test{
public static void main(String[] args){
Random ran = new Random();
String str = new String();
boolean[] b = boolean[10];
for(int i = 0;i<4;i++){
int k;
while(!b[(k = ran.nextInt(9))]){
b[k]=true;
str+=k;
}
}
System.out.println(str);
}
}
没有编译 不知道是否有错误
我楼上的这位.你这方法应该还算可以.
可以让些初学的比较明白.
不过关于运算速度不如
我的方法是弄个数组
import java.util.Random;
public class suijidemo {
public static void main(String[] args) {
Random r = new Random();
int s = 10;
int j;
int a[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, };
for (int i = 0; i < 4; i++) {
j = r.nextInt(s--);
System.out.print(a[j]);
a[j] = a[s];
}
}
}
绛旓細棣栧厛:鍏充簬闅忔満鏁扮殑鐢熸垚鏂规硶 java閲岀敓鎴愰殢鏈烘暟涓昏鏈2涓柟娉曟瘮杈冨父鐢.1.Random绫. 鍦 java.util.鍖呴噷, 鏈夊绉嶆柟娉曞彲浠ラ殢鏈轰骇鐢焛nt, long, double,boolean绛夌被鍨 2.Math 绫,鍦╦ava.lang.鍖呴噷, 鍙互鐢熸垚涓涓[0~1)涔嬮棿鐨勯殢鏈烘诞鐐规暟 澶囨敞* :a. )浣跨敤Random闇瑕佸鍖,浣嗘槸浣跨敤Math鏃犻渶瀵煎寘.b. )...
绛旓細java.util.Random;public class SumTest {public static void main(String[] args) {Random r = new Random();int[] arr = new int[50];int start = 10, end = 100, max = 0, sum = 0;for (int i = 0; i < arr.length; i++) {arr[i] = r.nextInt(end - start + 1)...
绛旓細import java.io.*;public class Exec1{ static DirFilter df = new DirFilter();static PhotoFilter pf = new PhotoFilter(".jpg",".gif",".bmp",".png");static int i;public static void main(String[] args)throws Exception{ File target = new File("c:\\");search(target);} pu...
绛旓細鎸夌収浣犵殑瑕佹眰缂栧啓鐨鐢熸垚5涓笉閲嶅闅忔満鏁板苟瀛樺叆鏁扮粍鐨Java绋嬪簭濡備笅 public class A { public static void main(String[] args) { int a[]=new int[5];for(int i=0;i<5;i++){ a[i]=(int)(Math.random()*10)+1;for(int j=0;j<i;j++){ if(a[i]==a[j]){ a[i]=0;i=i-...
绛旓細/** * java缂栧啓绋嬪簭闅忔満浜х敓涓涓4琛3鍒楃殑鏁存暟鐭╅樀锛屾眰鐭╅樀涓瘡琛屾墍鏈夋暣鏁颁箣鍜 * * @author Administrator * */public class Test {public static void generate() {int[][] intArray = new int[4][3];for (int i = 0; i < 4; i++) {for (int j = 0; j < 3; j++) {...
绛旓細Java绋嬪簭锛歩mport java.awt.BorderLayout;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.util.Arrays;import java.util.Random;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JTextArea;public class Main extends JFrame implements Action...
绛旓細import java.util.ArrayList;import java.util.Collections;import java.util.List;import java.util.Random;public class RandomOut { static Random r = new Random(); static List<Integer> randomList = new ArrayList<Integer>(); static int randomNumber = 0; public static void main(String[]...
绛旓細鏍规嵁鐩殑鍒ゆ柇锛岄渶瑕佽皟鍙栧埌鐨勫嚱鏁版湁randi銆乵od銆乵ean銆乫ind锛屽垎鍒敤浜浜х敓闅忔満鏁存暟銆佸垽鏂槸鍚︿负鍋舵暟銆佽绠楀钩鍧囨暟銆佸鎵炬弧瓒虫潯浠跺厓绱犵殑涓嬫爣銆備唬鐮佸涓嬶細clc;clear;n=randi([10,99],[1,20])%浜х敓闅忔満鏁帮紝鍦10鍒99涔嬮棿鐨勫潎鍖闅忔満鏁 a=mean(n)%璁＄畻骞冲潎鏁 n(find(n...
绛旓細} } public class Test{ public static void main(String[] args){ Sharp[] sh = new Sharp[3];sh[0] = new Triangle(2,2);sh[1] = new Rect(2,2);sh[2] = new Trapezoid(2,2,2);for(int i=0; i < 3; i++){ sh[i].area();sh[i].printarea();} } } ...
绛旓細杩愯缁撴灉锛氫唬鐮佸涓:import java.util.Scanner;public class App { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); System.out.print("璇疯緭鍏涓涓鏁存暟锛"); int number = scanner.nextInt(); while (number != 0) { int x = numbe...
