极客教程Java ArrayList的size()方法及示例
java.util.ArrayList 类的 size() 方法用于获取该列表中的元素数量。
语法
public int size()Java
返回值： 该方法返回该列表中的 元素数量 。
下面是说明size()方法的例子。
例1 :
// Java program to demonstrate
// size() method
// for Integer value
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
throws Exception
{
try {
// Creating object of ArrayList<Integer>
ArrayList<Integer>
arrlist = new ArrayList<Integer>();
// Populating arrlist1
arrlist.add(1);
arrlist.add(2);
arrlist.add(3);
arrlist.add(4);
arrlist.add(5);
// print arrlist
System.out.println("Before operation: "
+ arrlist);
// getting total size of arrlist
// using size() method
int size = arrlist.size();
// print the size of arrlist
System.out.println("Size of list = "
+ size);
}
catch (IndexOutOfBoundsException e) {
System.out.println("Exception thrown: "
+ e);
}
}
}Java
输出。
Before operation: [1, 2, 3, 4, 5]
Size of list = 5Java
例2 :
// Java program to demonstrate
// size() method
// for String value
import java.util.*;
public class GFG1 {
public static void main(String[] argv)
throws Exception
{
try {
// Creating object of ArrayList<Integer>
ArrayList<String>
arrlist = new ArrayList<String>();
// Populating arrlist1
arrlist.add("A");
arrlist.add("B");
arrlist.add("C");
// print arrlist
System.out.println("Before operation: "
+ arrlist);
// getting total size of arrlist
// using size() method
int size = arrlist.size();
// print the size of arrlist
System.out.println("Size of list = "
+ size);
}
catch (IndexOutOfBoundsException e) {
System.out.println("Exception thrown: "
+ e);
}
}
}Java
输出。
Before operation: [A, B, C]
Size of list = 3Java