我想用隨機數填充arrayList然後打印數組。但是,在執行程序時,我會遇到大量的錯誤。任何幫助,將不勝感激。用隨機數填充ArrayList然後打印數組
public class methods {
//variables
int capacity;
private static ArrayList<Double> randomArray;
public methods(int capacity) {
//default constructor to initalize variables and call populateArray to
//populate ArrayList with random numbers
randomArray = new ArrayList<>(capacity);
populateArray();
}
//Method that populates Array with random numbers
private void populateArray()
{
Random rand = new Random();
for (int i=0; i<= capacity; i++)
{
double r = rand.nextInt() % 256;
randomArray.add(i,r);
}
}
//Get Array adds numbers to the string that is called in my main class and printed
public String getArray() {
String result = "";
for (int i=0; i<= capacity; i++)
{
result += String.format("%4d", randomArray);
}
return result;
}
}
//main
public class Benchmarking {
public static void main (String args[]){
Scanner scanner = new Scanner(System.in);
System.out.println("What is the capacity of your Array?");
int capacity = scanner.nextInt();
methods array1 = new methods(capacity);
System.out.println(array1.getArray());
}
當我運行該程序並輸入它的容量崩潰。我只需要創建一個arrayList填充隨機數字並打印它。這裏是我收到的錯誤列表:
Exception in thread "main" java.util.IllegalFormatConversionException: d != java.util.ArrayList
at java.util.Formatter$FormatSpecifier.failConversion(Formatter.java:4302)
at java.util.Formatter$FormatSpecifier.printInteger(Formatter.java:2793)
at java.util.Formatter$FormatSpecifier.print(Formatter.java:2747)
at java.util.Formatter.format(Formatter.java:2520)
at java.util.Formatter.format(Formatter.java:2455)
at java.lang.String.format(String.java:2927)
at Benchmarking.methods.getArray(methods.java:68)
at Benchmarking.Benchmarking.main(Benchmarking.java:27)
我想我正在做一些根本上錯誤的方法。
這將有助於瞭解您所看到的錯誤。 – Jeremy
您不能將ArrayList格式化爲%4d。你是不是指'String.format(「%4d」,randomArray.get(i));'格式化列表中的某個特定元素? –