public class Practice {//构建字符串的3+1种方法

    public static void main(String[] args) {

        //第一种

        String one=new String();

        System.out.println("输出的字符串为："+one);

        //第二种

        char str[]={'A','B','C'};

        String two=new String(str);

        System.out.println("输出的字符串为："+two);

        //第三种

        byte []bytes={97,98,99,100};

        String three=new String(bytes);

        System.out.println("输出的字符串为："+three);

        //+1种 直接构造 字符串常量不可改变

        String four="HelloWorld";

        System.out.println("输出的字符串为："+four);

    }

}

public class Practice {

    public static void main(String[] args) {

     String one="Hello";

     System.out.println("字符串的长度为："+one.length());

     String two="say ".concat(one);

     System.out.println("字符串为："+two);

     for(int i=0;i<two.length();i++)

     {

         char ch=two.charAt(i);

         System.out.print(ch+" ");

     }

      String three="o";

      System.out.println("\n"+one.indexOf(three));

      String four="h";

      System.out.println(one.indexOf(four));

    }

}

public class Practice {

    public static void main(String[] args) {

     String one="hellobts";

     String two=one.substring(5);

     System.out.println(two);

     String three=one.substring(0, 5);

     System.out.println(three);

    }

}

public class Practice {

    public static void main(String[] args) {

     String one="hellobts";

     char a[]=one.toCharArray();

     for(int i=0;i<a.length;i++)

     {

         System.out.print(a[i]+" ");

     }

     System.out.println();

     byte []bytes=one.getBytes();

     for(int i=0;i<bytes.length;i++)

     {

         System.out.print(bytes[i]+" ");

     }

     System.out.println();

     String two=one.replace("hello", "love");

     System.out.println(two);

    }

}

public class Students {

     private static int idcounter=0;//每当创建一个对象（new)计数器++

      static String room;

     private String name;

     private int age;

     private int id;

     public Students() {

        this.id=++idcounter;

         }

     public Students(String name, int age) {

        this.name = name;

        this.age = age;

        this.id=++idcounter;

    }

    public int getId() {

        return id;

    }

    public void setId(int id) {

        this.id = id;

    }

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    public int getAge() {

        return age;

    }

    public void setAge(int age) {

        this.age = age;

    }

}

public class Practice {

    public static void main(String[] args) {

    Students one=new Students("田小娟",22);

    one.room="101教室";

    Students two=new Students("徐穗珍",22);

    System.out.println("姓名："+one.getName()+" "+"年龄："+one.getAge()+" 教室："+one.room+
" 学号"+one.getId());

    System.out.println("姓名："+two.getName()+" "+"年龄："+two.getAge()+" 教室："+two.room+
" 学号"+two.getId());

    }

}

import java.util.Arrays;

public class Practice {

    public static void main(String[] args) {

        int []num={3,89,45,235,43,79};

        String str=Arrays.toString(num);

        System.out.println(str);

        Arrays.sort(num);

        for(int i=0;i<num.length;i++)

        {

            System.out.print(num[i]+" ");

        }

    }

}

import java.util.Arrays;

public class Practice {

    public static void main(String[] args) {

        String str="aihfjsdfhuwefwnf";

        //定义一个随机的字符串，并将字符串排序后倒序输出

        //需将字符串先转化为字符数组，才能使用Arrays

        char []chars=str.toCharArray();

        Arrays.sort(chars);

        for(int i=chars.length-1;i>=0;i--)

        {

            System.out.print(chars[i]+" ");//w w u s n j i h h f f f f e d a

        }

    }

}