日撸代码300行：第11天

代码来自闵老师”日撸 Java 三百行（11-20天）“，链接：https://blog.csdn.net/minfanphd/article/details/116974461

package datastructure.list;/*** Sequential list* * @author WX873**/public class SequentialList {/*** The maximal length of the list. It is a constant.*/public static final int MAX_LENGTH = 10 ;/*** The actual length not exceeding MAX_LENTH. Attention:length is not only * the member variable of sequential list, but also the member variable of*  Array. In fact, a name can be the member variable of different classes.*/int length;/*** The data stored in an Array.*/int data[];/******************************************************** Construct an empty sequential list* ******************************************************/public SequentialList() {length = 0;data = new int[MAX_LENGTH];}//of the first constructor/******************************************************** Construct a sequential list using an array.* * @param paraArray* The given array. Its length should not exceed MAX_LENGTH* FOR simplicity now we do not check it.* ******************************************************/public SequentialList(int[] paraArray) {length = paraArray.length;data = new int[MAX_LENGTH];//copy datafor (int i = 0; i < paraArray.length; i++) {data[i] = paraArray[i];}//of for i}//of the second constructor/*** *********************************************************************** Overrides the method claimed in object, the superclass of any class.* ***********************************************************************/public String toString() {String resultString = "";if (length == 0) {return "empty";}//of iffor (int i = 0; i < data.length - 1; i++) {resultString += data[i] + ",";}//of for i//resultString += data[length - 1];return resultString;}//of toString/*** **************************************************** Reset to empty.* ****************************************************/public void reset() {length = 0;}//of reset/*** *************************************************** The entrance of the program.* ***************************************************/public static void main(String args[]) {int[] tempArray = {1,4,6,9,5,10};SequentialList tempFirstList = new SequentialList(tempArray);System.out.println("Initialized, the list is: " + tempFirstList.toString());System.out.println("Again, the list is: " + tempFirstList);tempFirstList.reset();System.out.println("After reset, the list is: " + tempFirstList);}//of main}//of SequentialList

1.通过本篇博客，学习了构造函数。构造函数是一种特殊的方法，主要用来在创建对象时初始化对象，即为对象成员变量赋初始值。一个类可以有多个构造函数，根据参数个数和参数类型的不同来区分。
（1）构造函数的功能主要用于在类的对象创建时定义初始化的状态，命名必须和类名相同。构造函数没有返回值，也不能被void修饰。
（2）构造函数不能被直接调用，必须通过new运算符在创建对象时才会调用。
2.第二个是遇到的困惑是tostring（）方法中，后面的resultString += data[length - 1]意义是什么？注释掉之后运行结果如下：

不注释这一句代码，会将tempArray = {1,4,6,9,5,10}的最后一个数附在最后，好像并没有实际价值。运行结果如下：