如果我有一个双精度浮点数数组:
[10.2, 20, 11.1, 21, 31, 12, 22.5, 32, 42, 13.6, 23, 32, 43.3, 53, 14, 24, 34, 44, 54, 64, 15.1, 25, 35, 45, 55, 65.3, 75.4, 16, 26, 17.5,]
我想获取第一个元素和最后一个元素,以便
firstNum = 10.2
lastNum = 17.5
我该怎么做?
如果我有一个双精度浮点数数组:
[10.2, 20, 11.1, 21, 31, 12, 22.5, 32, 42, 13.6, 23, 32, 43.3, 53, 14, 24, 34, 44, 54, 64, 15.1, 25, 35, 45, 55, 65.3, 75.4, 16, 26, 17.5,]
我想获取第一个元素和最后一个元素,以便
firstNum = 10.2
lastNum = 17.5
我该怎么做?
如果你有一个名为numbers
的双重数组,你可以使用:
firstNum = numbers[0];
lastNum = numbers[numbers.length-1];
或者使用 ArrayList
firstNum = numbers.get(0);
lastNum = numbers.get(numbers.size() - 1);
int[] array = {1, 2, 3, 4, 5};
int firstElement = array[0];
int lastElement = array[array.length - 1];
System.out.println("First Element: " + firstElement);
System.out.println("Last Element: " + lastElement);
import java.util.ArrayList;
int[] array = {1, 2, 3, 4, 5};
ArrayList<Integer> arrayList = new ArrayList<>();
// Convert the array to ArrayList
for (int i : array) {
arrayList.add(i);
}
int firstElement = arrayList.get(0);
int lastElement = arrayList.get(arrayList.size() - 1);
System.out.println("First Element: " + firstElement);
System.out.println("Last Element: " + lastElement);
// Array of doubles
double[] array_doubles = {2.5, 6.2, 8.2, 4846.354, 9.6};
// First position
double firstNum = array_doubles[0]; // 2.5
// Last position
double lastNum = array_doubles[array_doubles.length - 1]; // 9.6
这在任何数组中都是相同的。
请检查这个
double[] myarray = ...;
System.out.println(myarray[myarray.length-1]); //last
System.out.println(myarray[0]); //first
double[] numbers = {10.2, 20, 11.1, 21, 31, 12,
22.5, 32, 42, 13.6, 23, 32, 43.3, 53, 14, 24, 34,
44, 54, 64, 15.1, 25, 35, 45, 55, 65.3, 75.4, 16, 26, 17.5,};
double firstNumber= numbers[0];
double lastNumber = numbers[numbers.length-1];
System.out.println("firstNum = "+ firstNumber);
System.out.println("lastNum = "+ lastNumber);
int[] someArray = {1,2,3,4,5};
int first = someArray[0];
int last = someArray[someArray.length - 1];
System.out.println("First: " + first + "\n" + "Last: " + last);
输出:
First: 1
Last: 5
int myIntegerNumbers[] = {1,2,3,4,5,6,7,8,9,10};
int lastNumerOfArray= myIntegerNumbers[9];
Log.i("MyTag", lastNumerOfArray + "");
// 如果你想打印数组中元素的数量。
Log.i("MyTag", "The number of elements inside" +
"the array " +myIntegerNumbers.length);
//打印数组中最后一个元素的第二种方法。
Log.i("MyTag", "The last elements inside " +
"the array " + myIntegerNumbers[myIntegerNumbers.length-1]);
import java.util.Arrays;
import java.util.Optional;
String[] items = {"one", "two", "three"};
Optional<String> first = Arrays.stream(items).findFirst();
Optional<String> last = Arrays.stream(items).reduce((x, y) -> y);
items[0]
,您将会得到一个ArrayIndexOutOfBoundsException
。