学习java第40天

1.StringBuilder和StringBuffer用法一致，但是StringBuilder线程不安全，速度较快

2.StringBuilder和String的转换

public class StringBuilderTest1 {
    public static void main(String[] args) {
        StringBuilder strBui = new StringBuilder();
        strBui.append("hello").append("world");

        String str = strBui.toString();
        System.out.println("StringBuilder转换为String输出："+str);

        StringBuilder strBui1 = new StringBuilder(str);
        System.out.println("String转换为StringBuilder输出："+strBui1);
    }
}

//StringBuilder转换为String输出：helloworld

//String转换为StringBuilder输出：helloworld

3.StringBuilder的拼接，反转

public class StringBuilderTest2 {
    public static void main(String[] args) {
        StringBuilder strBui = new StringBuilder();
        strBui.append(hello).append("abc").append(123);   //拼接
        System.out.println(strBui);
        System.out.println(strBui.reverse());                         //反转
    }
}

// helloabc123

//321cbaolleh

4.字符串是否对称

public class StringBuilderTest3 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入一个字符串：");
        String str = sc.nextLine();
        boolean b = isSymmetry(str);
        System.out.println("是否对称："+b);
    }
    public static boolean isSymmetry(String str) {
        StringBuilder strBui = new StringBuilder(str);
        strBui.reverse();
        String strRes = strBui.toString();
        return strRes.equals(str);
    }
}

//请输入一个字符串:abc

//是否对称:false

5.明天学习内容：字符串的编码

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