StringBuilder，String, int轉為String

package com.company.project.builder;

import java.util.Random;

public class StringBuilderDemo {

    public static void main(String[] args) {
        StringBuilder sb = new StringBuilder("政立路477号1号樓");
        //插入，從第三個插入，第三個之後的後移,結果：政立路hehe477号1号樓
        System.out.println(sb.insert(, "hehe"));
        String str = "candsjkfdskgcanfskfdldscan";
        //找不到傳回-1
        System.out.println(str.indexOf("e"));
        //20位之後的第一個can,結果：23
        System.out.println(str.indexOf("can",));
        //是否以cani開始
        System.out.println(str.startsWith("cani"));
        //是否以scan3結尾
        System.out.println(str.endsWith("scan3"));
        //轉為大寫
        System.out.println(str.toUpperCase());
        //區index：3之後的部分
        System.out.println(str.substring());
        str=" zha ng    ";
        System.out.println(str);
        //去除前後的空格和tab
        System.out.println(str.trim());
        System.out.println(str);
        /**
         * 取得8位密碼
         */
        String ran = "";
        Random random = new Random();
        for(int i=;i<;i++){
            int num = random.nextInt();
            switch(num){
            case :
                //随機小字母
                char c = (char)(random.nextInt()+'a');
                ran += c;
                break;
            case :
                //随機大字母
                c = (char)(random.nextInt()+'A');
                ran += c;
            case :
                //随機數字
                int ii = random.nextInt();
                ran += ii;
            }
        }
        System.out.println(ran);//結果：rU4havg6C0

        int i1 = ;
        //int轉為String,以下2個方式
        System.out.println(String.valueOf(i1)+);
        System.out.println(i1+"");
    }

}