Question

我正在尝试使用string.format（）构造一个字符串，但它在中途停止工作（刚刚结束）。

private String constructMessage(String messageType, int messageCode,Position location) {
    double lat = location.getLat();
    double lon = location.getLon();
    double ele = location.getEle();
    double speed = 0.0;
    double heading = 0.0;

    String msg = "$PNGVEST," + messageType + "," + VEST_ID + ","
            + System.currentTimeMillis() + "," + lat + "," + lon + "," + ele
            + "," + speed + "," + heading + "," + messageCode;

    String test = String.format("$PNGVEST,%s,%d,%d,%f,%f,%f,$f,$f,$d",
            messageType, VEST_ID, System.currentTimeMillis(), lat, lon, ele,
            speed, heading, messageCode);

    System.out.println(msg);
    System.out.println(test);
    return msg;
}

当我运行上面的代码时，我得到以下输出：

$PNGVEST,LOCATION,1,1439998967553,51.558641765246364,-3.043043462354341,-1.0,0.0,0.0,0
$PNGVEST,LOCATION,1,1439998967553,51.558642,-3.043043,-1.000000,$f,$f,$d
$PNGVEST,LOCATION,1,1439998968553,51.55862560874394,-3.043027770590568,-1.0,0.0,0.0,0
$PNGVEST,LOCATION,1,1439998968553,51.558626,-3.043028,-1.000000,$f,$f,$d

为什么不格式化最后3个变量？

Answer 1

你用最后3个变量做了拼写错误。您注意到$f和$d而不是%f和%d。

应该是：

String test = String.format("$PNGVEST,%s,%d,%d,%f,%f,%f,%f,%f,%d",
        messageType, VEST_ID, System.currentTimeMillis(), lat, lon, ele,
        speed, heading, messageCode);

而不是

String.format("$PNGVEST,%s,%d,%d,%f,%f,%f,$f,$f,$d", ...);

Answer 2

尝试改变，

String test = String.format("$PNGVEST,%s,%d,%d,%f,%f,%f,$f,$f,$d",
        messageType, VEST_ID, System.currentTimeMillis(), lat, lon, ele,
        speed, heading, messageCode);

到

String test = String.format("$PNGVEST,%s,%d,%d,%f,%f,%f,%f,%f,%d",
        messageType, VEST_ID, System.currentTimeMillis(), lat, lon, ele,
        speed, heading, messageCode);

Java string.format（）只有一半工作

2 个答案: