importjava.util.ArrayList;publicclassMain{publicstaticvoidmain(String[]args){ArrayList<String>cars=newArrayList<String>();cars.add("Volvo");cars.add("BMW");cars.add("Ford");cars.add("Mazda");System.out.println(cars.contains("BMW"));System.out.println(cars.contains("Toyota"));}} ...
public boolean contains(Object o)The contains() method is used to determines whether an element exists in an ArrayList object. Returns true if this list contains the specified element. Package: java.utilJava Platform: Java SE 8 Syntax:contains(Object o)...
We have seen a few methods of the ArrayList class before likeadd(),addAll(),remove(),set(),iterate()andclear(). Today we will see thecontains()method. If we need to check if any element is present in the list or not, we can use thecontains()method from the ArrayList class in Ja...
ArrayList.Contains Method發行項 2011/09/08 本文內容 Syntax Version Information See Also Determines whether a specified object is contained in the ArrayList collection.Namespace: System.Collections Assembly: mscorlib (in mscorlib.dll)SyntaxC# 複製 public virtual bool Contains ( Object item ) ...
第二种是借助一个临时ArrayList,向临时List添加数据,调用arrayList.contains(obj)判断是否存在 了解ArrayList的contains原理:调用obj的equals方法进行判断在ArrayList中的位置是否大于零,进而判断是否存在。 publicbooleancontains(Object o) {returnindexOf(o) >= 0; ...
import java.util.Arrays;publicclassArrayListMethod {publicstaticvoidmain(String[] args) { ArrayList<Integer> list =newArrayList<>();//add(E e) add(int index, E e)list.add(1); list.add(2); list.add(0,0);//下标为0的数值设置为0;list.add(0); ...
boolean contains(Object o) //如果链表包含指定元素,返回true. int indexOf(Object o) //返回元素在链表中**第一次**出现的位置,如果返回-1,表示链表中没有这个元素。 int lastIndexOf(Object o) //返回元素在链表中**最后一次**出现的位置,如果返回-1,表示链表中没有这个元素。
Integer.MAX_VALUE : MAX_ARRAY_SIZE; } //返回ArrayList的大小 public int size() { return size; } // 判断ArrayList是否为空 public boolean isEmpty() { return size == 0; } //判断是否至少包含某一个元素 public boolean contains(Object o) { return indexOf(o) >= 0; } // 返回第一次出现...
/** * The size of the ArrayList (the number of elements it contains). * * @serial */ private int size; 看下ensureCapacityInternal()的源码: private void ensureCapacityInternal(int minCapacity) { ensureExplicitCapacity(calculateCapacity(elementData, minCapacity)); } 先说结论,该方法做了一件事情...
public boolean contains(Object o) { //indexOf()方法:返回此列表中指定元素的首次出现的索引,如果此列表不包含此元素,则为-1 return indexOf(o) >= 0; } /** * 返回此列表中指定元素的首次出现的索引,如果此列表不包含此元素,则为-1 */