In-depth understanding of the---------of the Java Collection Framework ArrayList collection-----Adding methods

ArrayList Collection-----Add method

1, add (e) Adding elements to the collection

　　

/** * Check if the array capacity is sufficient * @param mincapacity */public void ensurecapacity (int mincapacity) {Modcount++;int oldcapacity = Elementda Ta.length;if (Mincapacity > Oldcapacity) {Object olddata[] = elementdata;int newcapacity = (oldcapacity * 3)/2+1;if ( Newcapacity < mincapacity) {newcapacity  = Mincapacity;elementdata = arrays.copyof (Elementdata, newCapacity);}}}

/* (non-javadoc) * add element to ArrayList * @see Java.util.abstractlist#add (Java.lang.Object) */public boolean add (E e) { Ensurecapacity (size+1); elementdata[size++] = E;return true;}

2, add (int index, e e) Adds an element to the collection at the specified index

　　

/**     * Inserts the specified element at the specified position in this     * list. Shifts the element currently at, if any, and * any     subsequent elements to the right (adds one to their I ndices).     *     * @param index index at which the specified element was to being inserted     * @param element element to be Inserted
   * @throws indexoutofboundsexception {@inheritDoc}     *    /public void Add (int index, E element) {if (Index > size || Index < 0)    throw new Indexoutofboundsexception ("Index:" +index+ ", Size:" +size); ensurecapacity (size+1);  Increments modcount!! System.arraycopy (Elementdata, index, Elementdata, index + 1, size-index); Elementdata[index] = element;size++;    }

3, AddAll (collection<? Extends e> c) Add collection

　

  /* * add Element Collection * (non-javadoc) * @see Java.util.abstractcollection#addall (java.util.Collection) */public Boolean AddAll (collection<? extends e> c) {object[] a = C.toarray (); int numnew = A.length;ensurecapacity (size+numnew); System.arraycopy (A, 0, elementdata, size, numnew); Size+=numnew;return numnew!=0;}

4, AddAll (int index, COLLECTION<?) extends e> c); Adds a collection at the specified index

　　

public boolean addall (int index, COLLECTION<? extends e> c) {if (Index > Size | | Index < 0)    throw new Inde Xoutofboundsexception ("index:" + index + ", size:" + size); object[] A = C.toarray (); int numnew = A.length;ensurecapacity (size + numnew);  increments modcountint nummoved = size-index;if (nummoved > 0)    system.arraycopy (elementdata, index, ElementDat A, index + numnew,     nummoved);        System.arraycopy (A, 0, Elementdata, index, numnew); size + numnew;return numnew! = 0;    }

　　

In-depth understanding of the---------of the Java Collection Framework ArrayList collection-----Adding methods