该方法包含（obj o）在Java中做什么？
java.util的contains(Object)方法。如果此列表包含指定的元素，则ArrayList类返回true。
示例
import java.util.ArrayList;
public class ArrayListDemo {
public static void main(String[] args) {
ArrayList<Integer> arrlist = new ArrayList<Integer<(8);
arrlist.add(20);
arrlist.add(25);
arrlist.add(10);
arrlist.add(15);
for (Integer number : arrlist) {
System.out.println("Number = " + number);
}
boolean retval = arrlist.contains(10);
if (retval == true) {
System.out.println("element 10 is contained in the list");
} else {
System.out.println("element 10 is not contained in the list");
}
boolean retval2 = arrlist.contains(30);
if (retval2 == true) {
System.out.println("element 30 is contained in the list");
} else {
System.out.println("element 30 is not contained in the list");
}
}
}输出结果
Number = 20 Number = 25 Number = 10 Number = 15 element 10 is contained in the list element 30 is not contained in the list