Java 尝试计算数组中出现的次数
所以我试图计算这个程序中出现的整数的数量。代码仍然不起作用,但我走对了吗Java 尝试计算数组中出现的次数,java,arrays,count,find-occurrences,Java,Arrays,Count,Find Occurrences,所以我试图计算这个程序中出现的整数的数量。代码仍然不起作用,但我走对了吗 public static void main(String[] args) { Scanner scan = new Scanner(System.in); int userInput = 0; ArrayList<Integer> myList = new ArrayList<Integer>(); int[]
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
int userInput = 0;
ArrayList<Integer> myList = new ArrayList<Integer>();
int[] newArray = new int[myList.size()];
int index1 = -1;
int current;
for (int num = 0; num <= userInput ; num++)
{
System.out.println("Please enter a random number between 0 and 50, enter a negative number to end input: ");
num--;
if(userInput >= 0 || userInput <= 50)
{
userInput++;
userInput = scan.nextInt();
index1++;
myList.add(userInput);
}
if (userInput < 0 || userInput > 50)
{
myList.remove(index1);
index1--;
break;
}
}
for (int num2 = 0; num2 < myList.size(); num2++)
{
current = myList.get(num2);
if(current == myList.get(num2))
{
newArray[current-myList.get(num2)]++;
}
}
for (int number=0; number < newArray.length; number++)
{
System.out.println(number + "1");
System.out.println(" : " + newArray[number]);
}
}
}
publicstaticvoidmain(字符串[]args)
{
扫描仪扫描=新扫描仪(System.in);
int userInput=0;
ArrayList myList=新的ArrayList();
int[]newArray=newint[myList.size()];
int index1=-1;
电流;
对于(int num=0;num=0 | | userInput 50)
{
myList.remove(index1);
指数1--;
打破
}
}
对于(int num2=0;num2
编辑:
我只是想补充一点,我可以运行这个程序,但是当我输入一个超出边界的整数(不是0到50之间)时,我得到了一个错误,我刚刚写完这篇文章,感谢我修改代码时的否决票,并特别声明我正在修改代码。Hashmaps将在这里为您实现这一点
public static void main(String args[]) {
HashMap<Integer, Integer> numbers = new HashMap<Integer, Integer>();
Scanner scan = new Scanner(System.in);
boolean loop = true;
while (loop) {
System.out.println("Number: ");
int current = scan.nextInt();
if (current > 0 && current < 51) {
if (numbers.containsKey(current)) {
numbers.put(current, numbers.get(current)+1);
}else{
numbers.put(current, 1);
}
} else {
if(numbers.isEmpty()){
System.out.println("Nothing inputted");
loop = false;
}else{
for(Entry<Integer,Integer> e : numbers.entrySet()){
System.out.println(e.getKey() + " was entered " + e.getValue() + " times");
}
loop = false;
}
}
}
}
publicstaticvoidmain(字符串参数[]){
HashMap number=新的HashMap();
扫描仪扫描=新扫描仪(System.in);
布尔循环=真;
while(循环){
System.out.println(“编号:”);
int current=scan.nextInt();
如果(电流>0&&电流<51){
if(编号。容器(当前)){
数字.put(当前,数字.get(当前)+1);
}否则{
数字。输入(当前,1);
}
}否则{
if(numbers.isEmpty()){
系统输出打印项次(“无输入”);
循环=假;
}否则{
对于(条目e:numbers.entrySet()){
System.out.println(e.getKey()+“已输入”+e.getValue()+“次”);
}
循环=假;
}
}
}
}
您不需要任何像myList这样的附加集合。
您可以声明数组
int[] occurrences = new int[51];
它可以存储[0,50]范围内元素的出现。当您从扫描仪中读取n作为下一个字符串时,如果n在范围内,则应在readedn的第四个位置增加此数组的元素,否则应停止读取新值
如果statemest始终为true,则此选项为:
current = myList.get(num2);
if(current == myList.get(num2))
代码示例:
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int[] occurrrences = new int[51];
while (true){
int value = scanner.nextInt();
if(value>=0 && value<occurrrences.length){
occurrrences[value]++;
}else{
scanner.close();
break;
}
}
for (int i = 0; i < occurrrences.length; i++) {
if(occurrrences[i]>0){
System.out.println(i + " occured " + occurrrences[i] + " times.");
}
}
}
publicstaticvoidmain(字符串[]args){
扫描仪=新的扫描仪(System.in);
int[]发生率=新int[51];
while(true){
int value=scanner.nextInt();
如果(值>=0&&value0){
System.out.println(i+“发生”+发生次数[i]+“次数”);
}
}
}
问题出在哪里?想想这一行:int[]newArray=newint[myList.size()]代码>-提示:您正在创建一个空数组。甚至不会进入for循环int userInput=0;for(int num=0;num