java随机数陷阱

public class RandomTrap {
   static StringBuffer stringBuffer=new StringBuffer('D');//D被作为Int值传入
   static StringBuffer stringBuffer2=new StringBuffer("AB");
    public static void main(String[] args){
        stringBuffer.append('a');
        stringBuffer.append('b');
        stringBuffer2.append('c');
        stringBuffer2.append('d');
        System.out.println(stringBuffer);//输出：ab
        System.out.println(stringBuffer2);//输出：ABcd
    }
}

'D'被当作一个Int值传入

   public StringBuffer(int capacity) {
        super(capacity);
    }





 AbstractStringBuilder(int capacity) {
        value = new char[capacity];
    }

value=new char[capacity];创建一个容量为capacity大小的数组；