声明变量占一个空间，声明数组占用多个空间
数据类型 数组名[ ] ;
数据类型[ ] 数组名 ;
平均数计算
<div>int [ ] score = {60, 80, 90, 70, 85};</div><div>double avg;</div><div>avg = (score[0] + score[1] + score[2] + score[3] + score[4])/5; </div>
<div>int [ ] score = {60, 80, 90, 70, 85};</div><div>int sum = 0;</div><div>double avg;</div><div>for(int i = 0; i < score.length; i++){</div><div> sum = sum + score[i];</div><div>}</div><div>avg = sum / score.length; </div>
常见错误：
<div>编译出错，没有写明数组的大小</div>
运行时出错，数组下标越界
编译出错，创建数组并赋值的方式必须在一条语句中完成
<div> int[ ] score = new int[5];</div><div> score = {60, 80, 90, 70, 85};</div>
<div>int[ ] score2;</div><div> score2 = {60, 80, 90, 70, 85}; </div>
逆序：先升序在反序
<div>public static void main (String[] args){</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>char[] chars = new char[]{'a','c','b'};</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>System.out.println("原字符： ")；</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>for(int i= 0;i <ｃｈａｒｓ．ｌｅｎｇｔｈ；ｉ＋＋)｛</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>Ｓｙｓｔｅｍ．ｏｕｔ．ｐｒｉｎｔｌｎ（ｃｈａｒｓ［ｉ］）；</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>｝</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>Ａｒｒａｙｓ．ｓｏｒｔ（ｃｈａｒ）；</div><div> Ｓｙｓｔｅｍ．ｏｕｔ．ｐｒｉｎｔｌｎ（＂升序 ：＂）；</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>ｆｏｒ（ｉｎｔ ｉ ＝ ０； ｉ＜ ｓｈａｒｓ．ｌｅｎｇｌｎ；ｉ＋＋）｛</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>Ｓｙｓｔｅｍ．ｏｕｔ．ｐｒｉｎｔｌｎ（＂ｓｈａｒｓ［ｉ］＋＂＂）；</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>｝</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>Ｓｙｓｔｅｍ．ｏｕｔ．ｐｒｉｎｔｌｎ（＂逆序＂）；</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>ｆｏｒ（ｉｎｔ ｉ ＝ ｃｈａｒｓ．ｌｅｎｇｔｈ－１；ｉ＞＝０；ｉ＋＋）｛</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>Ｓｙｓｔｅｍ．ｏｕｔ．ｐｒｉｎｔｌｎ（ｃｈａｒｓ［ｉ］＋ ＂＂）；</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>｝</div><div>｝</div><div><br></div>
是一组变量，存储相同类型的一组数据（引用型变量）
三种赋值方法：
int[ ] score = {89, 79, 76};
int[ ] score = new int[ ]{89, 79, 76};
<p style="language:zh-CN;margin-top:10.8pt;margin-bottom:0pt;text-align:left;
direction:ltr;unicode-bidi:embed;vertical-align:baseline"><span style="font-family:Arial;mso-ascii-font-family:Arial;mso-fareast-font-family:
宋体;mso-bidi-font-family:Arial;color:#3333FF;mso-font-kerning:12.0pt;language:
en-US;font-weight:bold;mso-style-textfill-type:solid;mso-style-textfill-fill-color:
#3333FF;mso-style-textfill-fill-alpha:100.0%">int</span><span style="font-family:
Arial;mso-ascii-font-family:Arial;mso-fareast-font-family:宋体;mso-bidi-font-family:
Arial;color:black;mso-font-kerning:12.0pt;language:en-US;font-weight:bold;
mso-style-textfill-type:solid;mso-style-textfill-fill-color:black;mso-style-textfill-fill-alpha:
100.0%">[ ] score ;</span><span style="font-family:Arial;mso-ascii-font-family:
Arial;mso-fareast-font-family:宋体;mso-bidi-font-family:Arial;color:black;
mso-font-kerning:12.0pt;language:zh-CN;font-weight:bold;mso-style-textfill-type:
solid;mso-style-textfill-fill-color:black;mso-style-textfill-fill-alpha:100.0%"><br>
</span><span style="font-family:Arial;mso-ascii-font-family:Arial;mso-fareast-font-family:
宋体;mso-bidi-font-family:Arial;color:black;mso-font-kerning:12.0pt;language:
en-US;font-weight:bold;mso-style-textfill-type:solid;mso-style-textfill-fill-color:
black;mso-style-textfill-fill-alpha:100.0%">score = new </span><span style="font-family:Arial;mso-ascii-font-family:Arial;mso-fareast-font-family:
宋体;mso-bidi-font-family:Arial;color:black;mso-font-kerning:12.0pt;language:
en-US;font-weight:bold;mso-style-textfill-type:solid;mso-style-textfill-fill-color:
black;mso-style-textfill-fill-alpha:100.0%">int</span><span style="font-family:
Arial;mso-ascii-font-family:Arial;mso-fareast-font-family:宋体;mso-bidi-font-family:
Arial;color:black;mso-font-kerning:12.0pt;language:en-US;font-weight:bold;
mso-style-textfill-type:solid;mso-style-textfill-fill-color:black;mso-style-textfill-fill-alpha:
100.0%">[]{89,79,76};</span></p>
动态赋值：
<div>Scanner input = new Scanner(System.in);</div><div>for(int i = 0; i < 30; i ++){</div><div> score[i] = input.nextInt();</div><div>}</div>
升序
<div><b>使用java.util.Arrays类</b></div><div>java.util包提供了许多工具类</div><div>Arrays类提供操作数组的方法，例排序、查询</div><div>Arrays类的sort()方法: 对数组进行升序排列</div><div><br></div>
<div>import java.util.*; //导入包</div><div> ……</div><div> int[] scores = new int[5];<span class="Apple-tab-span" style="white-space:pre"> </span>//成绩数组</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>Scanner input = new Scanner(System.in);</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>System.out.println("请输入5位学员的成绩：");</div><div><span class="Apple-tab-span" style="white-space:pre"> </span><b>for(int i = 0; i < scores.length; i++){</b></div><div><b><span class="Apple-tab-span" style="white-space:pre"> </span>scores[i] = input.nextInt();</b></div><div><b><span class="Apple-tab-span" style="white-space:pre"> </span>}</b></div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span><b>Arrays.sort(scores);</b><span class="Apple-tab-span" style="white-space:pre"><b> </b> </span></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>System.out.print("学员成绩按升序排列：");</div><div><span class="Apple-tab-span" style="white-space:pre"> </span><b>for(int i = 0; i < scores.length; i++){</b></div><div><b><span class="Apple-tab-span" style="white-space:pre"> </span>System.out.print(scores[i] + " ");</b></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>}</div>
<b>循环录入学生成绩并存储在数组中</b><br>
<b>数组中的元素被重新排列</b><br>
<p style="margin-top: 0pt; margin-bottom: 0pt; direction: ltr; unicode-bidi: embed; vertical-align: baseline;"><span style="font-family:黑体;mso-ascii-font-family:Arial;mso-fareast-font-family:黑体;
mso-bidi-font-family:Arial;color:black;mso-font-kerning:12.0pt;language:zh-CN;
font-weight:bold;mso-style-textfill-type:solid;mso-style-textfill-fill-color:
black;mso-style-textfill-fill-alpha:100.0%">循环输出数组中的信息</span></p>
<b>按英文排列歌曲（排列字符串）</b>
<div>String[] musics = new String[]{"Island","Ocean","Pretty","Sun"};</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>//插入歌曲后的数组</div><div><span class="Apple-tab-span" style="white-space:pre"> </span><b>String[] newMusics = new String[musics.length+1];<span class="Apple-tab-span" style="white-space:pre"> </span></b></div><div><b><span class="Apple-tab-span" style="white-space:pre"> </span>String music = "";<span class="Apple-tab-span" style="white-space:pre"> </span>//保存用户输入的歌曲名称</b></div><div><b><span class="Apple-tab-span" style="white-space:pre"> </span>int index = musics.length;<span class="Apple-tab-span" style="white-space:pre"> </span>//保存新歌曲插入位置</b></div><div><span class="Apple-tab-span" style="white-space:pre"> </span></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>//输出插入前的结果</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>System.out.print("插入前的数组为：");</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>for(int i = 0; i < musics.length ; i++){<span class="Apple-tab-span" style="white-space:pre"> </span></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>System.out.print(musics[i]+" ");</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>} </div><div><br></div>
<div>//将数组musics中的元素复制到数组newMusics中</div><div><span class="Apple-tab-span" style="white-space:pre"> </span><b>for(int i = 0; i < musics.length; i++){</b></div><div><b><span class="Apple-tab-span" style="white-space:pre"> </span>newMusics[i] = musics[i];</b></div><div><b><span class="Apple-tab-span" style="white-space:pre"> </span>}</b></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>//输入歌曲名称</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>Scanner input = new Scanner(System.in);</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>System.out.print("\n请输入歌曲名称：");</div><div><span class="Apple-tab-span" style="white-space: pre;"> </span>music = input.next();</div><div><br></div>
<div>//找到新元素的插入位置</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>for(int i = 0; i < musics.length; i++){</div><div><span class="Apple-tab-span" style="white-space:pre"> </span><b>if(musics[i].compareToIgnoreCase(music) > 0){</b></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>index = i;</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>break;</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>}</div>
<p style="language:zh-CN;margin-top:10.8pt;margin-bottom:0pt;text-align:left;
direction:ltr;unicode-bidi:embed;vertical-align:baseline"><span style="font-family:Arial;mso-ascii-font-family:Arial;mso-fareast-font-family:
黑体;mso-bidi-font-family:Arial;color:black;mso-font-kerning:12.0pt;language:
zh-CN;font-weight:bold;mso-style-textfill-type:solid;mso-style-textfill-fill-color:
black;mso-style-textfill-fill-alpha:100.0%">//元素后移</span></p>
<p style="language:zh-CN;margin-top:10.8pt;margin-bottom:0pt;text-align:left;
direction:ltr;unicode-bidi:embed;vertical-align:baseline"><span style="font-family:Arial;mso-ascii-font-family:Arial;mso-fareast-font-family:
黑体;mso-bidi-font-family:Arial;color:black;mso-font-kerning:12.0pt;language:
zh-CN;font-weight:bold;mso-style-textfill-type:solid;mso-style-textfill-fill-color:
black;mso-style-textfill-fill-alpha:100.0%"> for(int
i = newMusics.length-1; i > index; i--){</span></p>
<p style="language:zh-CN;margin-top:10.8pt;margin-bottom:0pt;text-align:left;
direction:ltr;unicode-bidi:embed;vertical-align:baseline"><span style="font-family:Arial;mso-ascii-font-family:Arial;mso-fareast-font-family:
黑体;mso-bidi-font-family:Arial;color:black;mso-font-kerning:12.0pt;language:
en-US;font-weight:bold;mso-style-textfill-type:solid;mso-style-textfill-fill-color:
black;mso-style-textfill-fill-alpha:100.0%"> </span><span style="font-family:Arial;mso-ascii-font-family:Arial;mso-fareast-font-family:
黑体;mso-bidi-font-family:Arial;color:black;mso-font-kerning:12.0pt;language:
zh-CN;font-weight:bold;mso-style-textfill-type:solid;mso-style-textfill-fill-color:
black;mso-style-textfill-fill-alpha:100.0%"> //index下标开始的元素后移一个位置</span></p>
<p style="language:zh-CN;margin-top:10.8pt;margin-bottom:0pt;text-align:left;
direction:ltr;unicode-bidi:embed;vertical-align:baseline"><span style="font-family:Arial;mso-ascii-font-family:Arial;mso-fareast-font-family:
黑体;mso-bidi-font-family:Arial;color:black;mso-font-kerning:12.0pt;language:
zh-CN;font-weight:bold;mso-style-textfill-type:solid;mso-style-textfill-fill-color:
black;mso-style-textfill-fill-alpha:100.0%"> </span><span style="font-family:Arial;mso-ascii-font-family:Arial;mso-fareast-font-family:
黑体;mso-bidi-font-family:Arial;color:black;mso-font-kerning:12.0pt;language:
en-US;font-weight:bold;mso-style-textfill-type:solid;mso-style-textfill-fill-color:
black;mso-style-textfill-fill-alpha:100.0%"> </span><span style="font-family:Arial;
mso-ascii-font-family:Arial;mso-fareast-font-family:黑体;mso-bidi-font-family:
Arial;color:black;mso-font-kerning:12.0pt;language:zh-CN;font-weight:bold;
mso-style-textfill-type:solid;mso-style-textfill-fill-color:black;mso-style-textfill-fill-alpha:
100.0%">newMusics[i] = newMusics[i-1]; </span></p>
<p style="language:zh-CN;margin-top:10.8pt;margin-bottom:0pt;text-align:left;
direction:ltr;unicode-bidi:embed;vertical-align:baseline"><span style="font-family:Arial;mso-ascii-font-family:Arial;mso-fareast-font-family:
黑体;mso-bidi-font-family:Arial;color:black;mso-font-kerning:12.0pt;language:
en-US;font-weight:bold;mso-style-textfill-type:solid;mso-style-textfill-fill-color:
black;mso-style-textfill-fill-alpha:100.0%"> </span><span style="font-family:Arial;mso-ascii-font-family:Arial;mso-fareast-font-family:
黑体;mso-bidi-font-family:Arial;color:black;mso-font-kerning:12.0pt;language:
zh-CN;font-weight:bold;mso-style-textfill-type:solid;mso-style-textfill-fill-color:
black;mso-style-textfill-fill-alpha:100.0%">}</span></p>
<p style="language:zh-CN;margin-top:10.8pt;margin-bottom:0pt;text-align:left;
direction:ltr;unicode-bidi:embed;vertical-align:baseline"><span style="font-family:Arial;mso-ascii-font-family:Arial;mso-fareast-font-family:
黑体;mso-bidi-font-family:Arial;color:black;mso-font-kerning:12.0pt;language:
zh-CN;font-weight:bold;mso-style-textfill-type:solid;mso-style-textfill-fill-color:
black;mso-style-textfill-fill-alpha:100.0%"> newMusics[index]
= music; //新元素放在index的位置</span></p>
<div> 元素后移</div><div><span class="Apple-tab-span" style="white-space:pre"> </span></div><div>//输出插入后的结果</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>System.out.print("插入后的数组为：");</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>for(int i = 0; i < newMusics.length; i++){</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>System.out.print(newMusics[i]+" ");</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div><br></div>
<p style="margin-top: 0pt; margin-bottom: 0pt; direction: ltr; unicode-bidi: embed; vertical-align: baseline;"><span style="font-family:黑体;mso-ascii-font-family:Arial;mso-fareast-font-family:黑体;
mso-bidi-font-family:Arial;color:black;mso-font-kerning:12.0pt;language:zh-CN;
font-weight:bold;mso-style-textfill-type:solid;mso-style-textfill-fill-color:
black;mso-style-textfill-fill-alpha:100.0%">注意第二个数组的定义方式以及新歌曲插入位置的变量定义方式</span></p>
<b>复制一个数组</b>
<div><b>字符串比较</b></div><div><b>compareTo( ) ：不忽略大小写</b></div><div><b>compareToIgnoreCase( )：忽略大小写 </b></div>
<b> 元素后移</b><br>
