自学Java测试代码二String， StringBuffer

2017-08-23 10:38:01

writer：pprp

package test;
import java.util.*;

public class test2 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println("welcome to test2");
        //记住数组初始化应该这样
        int[] d = new int[]{1,2,3,4};
        //字符串的处理
        String str;
        str = "everybody - AI";
        System.out.println(str);

        //自己看了一下Java的输入操作，很麻烦
        Scanner in = new Scanner(System.in);
        int a = in.nextInt();
        System.out.println(a);

        //字符串类型的输入
        String tmp = in.next();
        System.out.println(tmp);

        in.close();

        //字符串相关操作
        String str1 = "very";
        str1 = str1 + " good";
        System.out.println(str1);

        //字符串的处理类String
        String str3 = new String();
        System.out.println(str3);

        //字节参数的构造器
        byte[] b = {97,98,99,100,101,102,103};//分别代表abc
        String str4 = new String(b);
        System.out.println(str4);

        //字符串数组的构造器
        char[] c = {'w','r','i','t','e','r'};
        String str6 = new String(c);
        System.out.println(str6);

        String str7 = new String(c,3,2);
        System.out.println(str7);

        //获取指定字节的构造器,从第三位开始取三位
        String str5 = new String(b,3,3);
        System.out.println(str5);

        //字符串的处理方法
        //1、串链接 用＋号或者用函数concat
        String str2 = "you";
        String str8 = "welcome";
        System.out.println(str8.concat(str2));
        System.out.println(str8);//函数没有改变这个子串本身

        //提取子字符串
        String str9 = "Without tears and sweats ,nothing will come for you";
        System.out.println(str9.substring(0,6));
        System.out.println(str9.substring(8));

        //分解字符
        System.out.println(str9.charAt(0));
        //长度
        System.out.println(str9.length());

        //字符串是否相等
        String s0 = "administrator";
        String s1 = "Administrator";
        if(s0.equals(s1))
        {
            System.out.println("test1: equal");
        }
        if(s0.equalsIgnoreCase(s1))
        {
            System.out.println("test2: equal");
        }

        //查找特定子串
        String s2 = "没有付出汗水和泪水，就什么也不会得到";
        System.out.println(s2.indexOf("和泪水"));
        System.out.println(s2.startsWith("没有"));
        System.out.println(s2.endsWith("得到"));

        //StringBuffer缓冲字符串
        StringBuffer sb1 = new StringBuffer();
        System.out.println(sb1.capacity() + "　　" +sb1.length());

        //StringBuffer的处理
        StringBuffer sb2 = new StringBuffer("I wanna become ");
        sb2.append("a great acmer");
        System.out.println(sb2);
        sb2.setLength(25);
        System.out.println(sb2);
        System.out.println(sb2.charAt(1));
        sb2.setCharAt(1, 'P');
        System.out.println(sb2);

        //指定位置插入字符
        sb2.insert(1," writer:pprp ");
        System.out.println(sb2);

        //从尾部插入子串
        sb2.append("date:2017/8/23");
        System.out.println(sb2);

        //倒置
        System.out.println(sb2.reverse());
    }

}