day13

package com.heima.test;

import java.util.Arrays;
//01-08 Stringbuffer相关
//09    Arrays相关
public class Test13 {
    public static void main(String[] args) {
//        demo01();     length capacity
//        demo02();     append insert
//        demo03();     delete deleteCharAt
//        demo04();     replace reverse
//        demo05();     substring
//        demo06();     字符串转Stringbuffer:append 构造方法
//        demo07();     Stringbuffer转字符串:String构造 直接打印引用 截取方法
//        demo08();     Stringbuffer和Stringbiuder和String的区别

//        具体可看13.11
//        基本数据类型的值传递,不改变其值.
//        引用数据类型的值传递,改变其值.(String虽然是引用数据类型,但是不改变值)

//        demo09();     Arrays的 tostring sort binarysearch

//        基本数据类型的包装类
//        byte=Byte short=Short int=Integer long=Long float=Float double=Double char=Character boolean=Boolean

//        demo10();     Integer包装类
//        demo11();     int转String String转int


    }

    public static void demo11() {
        //int转String 4种方法
        //a
        int i=100;
        String str=i+"";
        System.out.println(str);

        //b
        int i2=200;
        String str2=String.valueOf(i2);
        System.out.println(str2);

        //c
        int i3=300;
        Integer in=new Integer(i3);
        String str3=in.toString();
        System.out.println(str3);

        //d
        int i4=400;
        String str4=Integer.toString(i4);
        System.out.println(str4);

        //String转int两种方法
        //a
        Integer in2=new Integer("500");
        int in3=in2.intValue();
        System.out.println(in3);

        //b
        int in4=Integer.parseInt("600");
        System.out.println(in4);
    }

    public static void demo10() {
        Integer in=new Integer(100);
        System.out.println(in);

        Integer in2=new Integer("100");
        System.out.println(in2);

        System.out.println(Integer.MAX_VALUE);
        System.out.println(Integer.MIN_VALUE);
    }

    public static void demo09() {
        int[] i={11,453,33,9,42,91};

        //Arrays.toString int数组转字符串
        String str= Arrays.toString(i);//[11, 22, 33, 44, 55, 66]
        System.out.println(str);

        //Arrays.sort int数组排序
        Arrays.sort(i);//sort没有返回值
        System.out.println(i);//[I@29ce8c
        String str2=Arrays.toString(i);//[9, 11, 33, 42, 91, 453]
        System.out.println(str2);

        //Arrays.binarySearch int数组二分查找(前提是:需要已经排序好的数组)
        System.out.println(Arrays.binarySearch(i,9));//0
        System.out.println(Arrays.binarySearch(i,33));//2
        System.out.println(Arrays.binarySearch(i,91));//4
        System.out.println(Arrays.binarySearch(i,999));//-7(负的插入点-1)
    }

    public static void demo08() {
        /*
        Stringbuffer和Stringbiuder的区别:
        1.前者为jdk1.0版本的,后者为jdk1.5版本
        2.前者线性安全,后者线性不安全

        String和以上两者的区别:
        1.前者不可变字符序列,后者可变字符序列
        * */
    }

    public static void demo07() {
        //string的构造转换
        StringBuffer sb=new StringBuffer("zhangyan");
        String str=new String(sb);//zhangyan
        System.out.println(str);

        //Stringbuffer的截取转换
        StringBuffer sb2=new StringBuffer("yanjing");
        String str2=sb2.substring(0,sb2.length());//yanjing
        System.out.println(str2);

        //直接打印Stringbuffer的引用
        StringBuffer sb3=new StringBuffer("lisi");//lisi
        System.out.println(sb3);
    }

    public static void demo06() {
        //append 字符串转Stringbuffer
        StringBuffer sb=new StringBuffer();
        sb.append("zhangyan");//zhangyan
        System.out.println(sb);

        //构造方法 字符串转Stringbuffer
        StringBuffer sb2=new StringBuffer("yanjin");
        System.out.println(sb2);//yanjin
    }

    public static void demo05() {
        //substring 截取下表后字符
        StringBuffer sb=new StringBuffer("zhangyan");
        String str=sb.substring(5);//yan
        System.out.println(str);

        //substring 开头截取到指定下标(包含头不包含尾
        StringBuffer sb2=new StringBuffer("zhangyan");
        String str2=sb.substring(0,5);//zhang
        System.out.println(str2);
    }

    public static void demo04() {
        StringBuffer sb=new StringBuffer();
        sb.append("abcde");

        //replace
        sb.replace(0,2,"AA");//AAcde
        System.out.println(sb);

        //reverse
        sb.reverse();//edcAA
        System.out.println(sb);
    }

    public static void demo03() {
        StringBuffer sb=new StringBuffer();
        sb.append("abcde");

        //deleteCharAt
        StringBuffer dsb=sb.deleteCharAt(1);//acde
        System.out.println(dsb);

        //delete
        StringBuffer dasb=sb.delete(0,2);//de
        System.out.println(dasb);

        //delete清空数据区
        StringBuffer dallsb=sb.delete(0,sb.length());
        System.out.println(dallsb);
    }

    public static void demo02() {
        //append
        StringBuffer sb=new StringBuffer();
        StringBuffer sb2=sb.append("abc");
        StringBuffer sb3=sb.append(10);
        StringBuffer sb4=sb.append(true);
        System.out.println(sb);//abc10true

        //inster
        StringBuffer sb5=sb.insert(3,"AAA");
        System.out.println(sb5);//abcAAA10true
    }

    public static void demo01() {
        /*
        * 三种实例化StringBuffer的方法
        * */
        StringBuffer sb=new StringBuffer();
        int i=sb.length();//0   实际字符数
        int i2=sb.capacity();//16  容器初始容量
        System.out.println(i);
        System.out.println(i2);

        StringBuffer sb2=new StringBuffer("zhangsan");
        int i3=sb2.length();//8  实际字符数
        int i4=sb2.capacity();//24  容器初始容量+实际字符数
        System.out.println(i3);
        System.out.println(i4);

        StringBuffer sb3=new StringBuffer(10);
        int i5=sb3.length();//0
        int i6=sb3.capacity();//10
        System.out.println(i5);
        System.out.println(i6);
    }
}