String API

/**
 * public final class String
 * String 是包装类型，且为final修饰不能被继承
 * 一下提供字符串拼接和字符串反转的方法
 */
public class StringUtils {

    public static void main(String[] args) {
        StringUtils.stringJoin();
        StringUtils.stringReverse();
    }


    public static void stringJoin(){

        //StringBuffer字符串连接 线程安全的
        StringBuffer buffer = new StringBuffer();
        buffer.append("a");
        buffer.append("b");
        buffer.append("c");
        buffer.append("d");
        System.out.println(buffer.toString());

        //StringBuilder字符串连接， 非线程安全的，但是速度快
        StringBuilder builder = new StringBuilder();
        builder.append("a");
        builder.append("b");
        builder.append("c");
        builder.append("d");
        System.out.println(builder.toString());
    }


    //字符串反转
    public static void stringReverse(){
        // StringBuffer reverse
        StringBuffer stringBuffer = new StringBuffer();
        stringBuffer.append("abcdefg");
        System.out.println(stringBuffer.reverse()); // gfedcba

        // StringBuilder reverse
        StringBuilder stringBuilder = new StringBuilder();
        stringBuilder.append("abcdefg");
        System.out.println(stringBuilder.reverse()); // gfedcba
    }
}