StringBuffer 线程安全与StringBuilder 线程非安全

/**
 * StringBuffer 线程安全
 * StringBuilder 线程非安全
 * @author 909974
 *
 */
public class Test1 {
    public static void main(String[] argaa) {
        MyString sb = new MyString();
        StringBuilder sbBuilder = new StringBuilder();
        StringBuffer stringBuffer = new StringBuffer();
        for (int i = 0; i < 1000; i++) {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    for (int j = 0; j < 1000; j++) {
                        sb.append(1);
                        sbBuilder.append("1");
                        stringBuffer.append("1");
                        System.out.println(sb.getNum() + "-" + sbBuilder.length() + "-" + stringBuffer.length());
                    }
                }
            }).start();
        }
    }
}


class MyString {
    private Integer num = 0;

    public Integer getNum() {
        return num;
    }

    public void setNum(Integer num) {
        this.num = num;
    }

    public  synchronized void append(Integer num) {
        this.num = this.num + num;
    }
}