String

charAT():提取指定字元
codePointAt(): 提取縮印字串轉為數字
codePointBefore(): 提取索引字串的前一個字元轉為數字
codePointCount(a,b): 返回a,b 之間的Unicode 的個數
a.compareTo(b) :比較a,b的大小 a>b:1 a=b:0 a<b:-1 返回int型別 (注：只能是string比較)
compareToIgnoreCase(): 忽略大小寫比較
concat :字串拼接：（不能指定位置）
contains（String ）:判斷是否包含指定字元。 返回bool值 注：只能與string匹配

（b:boolean s:string c:char x:16 o:8 d:10進位制 e：科學計數 %%：% ）

    public static void main(String[] args) {
        String strCom = "i like java";
        String strCom2 = "happy every day ";
        int strLower = strCom.codePointAt(5);
        int strLowerb = strCom.codePointBefore(5);
        int strLowerCount = strCom.codePointCount(2,5);
        System.out.println(strLower);
        System.out.println(strLowerb);
        System.out.println(strLowerCount);
        System.out.println((char)101);
        System.out.println((char)107);
        int  n1 = strCom.compareTo(strCom2);
        System.out.println(n1);
//        cha,int彙報錯
//        int c1 =1 ,c2 =3;
//        System.out.println(c1.compareTo(c2));
        System.out.println(strCom.concat(strCom2));
        System.out.println(strCom.contains("java1"));
        char[] arry = {'i','o','k'};
        String str = String.copyValueOf(arry,1,1);
        System.out.println(str);
        boolean b2 = strCom.equals(n1);
        System.out.println(b2);
        boolean b3 = strCom.equalsIgnoreCase(strCom2);
        String formatDemo = String.format("hello %s,my name is %s,my age is %d","world",             注意寫法：  %d表示數字
                "huluwa",19);
        System.out.println(formatDemo);
        String str1 = String.format("%d",400/2);
        String str2 = String.format("%b",3>4);
 

        System.out.println(str1);
        System.out.println(str2);

}

　String str= String.format(local i , String format,args); %te tb/tB tA/ta tc tY tj tm td ty

 Date date = new Date();
        Locale form = Locale.CHINA;
        String year = String.format(form,"%tY",date);
        String month  = String.format(form,"%tb",date);
        String day = String.format(form,"%td",date);

        System.out.println(year+month+day);

getBytes() str1 = strCom.getBytes("utf-8");注意要catch以下 否則會報錯 str1 = strCom.getBytes(Charset.defaultCharset()); 虛擬機器預設的byte序列

        String strCom = "java";
        byte[]  str= strCom.getBytes();
        System.out.println(str);

        for (int i = 0;i<str.length;i++)
        {
            System.out.println(str[i]);
        }
    }

getChars(str第一個索引 strend索引 陣列 陣列偏移量)

     String strCom = "l Like Java";
        char[] dst = new char[10];
        strCom.getChars(0,10,dst,0);
        for (int i=0;i<dst.length;i++)
        {
            System.out.println(dst[i]);
        }