如何将值附加到StringBuilder数组

Question

我正在解析十进制格式的网格坐标.我想将模式匹配存储在StringBuilder数组中以便进一步操作.但是,在每个while循环中调用append()时,我得到一个空指针.

String coordinateExample = "N14585928W084144340";
this.parseCoordinate(coordinateExample);
...

public void parseCoordinate(String coordinateString) {

    int i = 0;

    //extract NSEW leading characters
    Pattern pL = Pattern.compile("[A-Z]");
    Matcher m = pL.matcher(coordinateString);        
    StringBuilder[] hemisphere = new StringBuilder[]{};

    while (m.find()) {
        hemisphere[i].append(m.group());
        //System.out.println("m.group(): " + m.group());
        i++;
    }        
    // reset i
    i = 0;

    //extract decimal degree digits
    Pattern pN = Pattern.compile("[0-9]++");
    Matcher n = pN.matcher(coordinateString);
    StringBuilder[] coordinate = new StringBuilder[]{};

    while (n.find()) {            
        coordinate[i].append(n.group());
        //System.out.println("q.group(): " + n.group());
        i++;
    }
}

Answer 1

StringBuilder[] coordinate = new StringBuilder[]{};

这是创建一个空数组,可以包含StringBuilder类型的实例.你最想做的是:

StringBuilder coordinate = new StringBuilder();

它创建了一个可附加到的实际StringBuilder对象.