Question

嗨，我有一个文件列表。我想显示每个文件的文件长度。我创建自己的方法来获取文件长度和正确的单位（基值）。

来源

public String getFileLength(long lengthBytes){
    Log.i("", 1 + " -- FILE INFO -- " + lengthBytes);
    String lengthString;
    if(lengthBytes<1024){
        Log.i("", 21 + " -- FILE INFO B -- " + lengthBytes);
        lengthString = lengthBytes + " B";
        Log.i("", 22 + " -- FILE INFO B -- " + lengthString);
    } else if (lengthBytes<(1024^2)){
        Log.i("", 31 + " -- FILE INFO KB -- " + lengthBytes);
        //length = String.valueOf(Math.round(i/1024)) + " KB";
        lengthString = lengthBytes/1024 + " KB";
        Log.i("", 32 + " -- FILE INFO KB -- " + lengthString);
    } else if (lengthBytes<(1024^3)){
        Log.i("", 41 + " -- FILE INFO MB -- " + lengthBytes);
        lengthString = lengthBytes/(1024^2) + " MB";
        Log.i("", 42 + " -- FILE INFO MB -- " + lengthBytes);
    } else if (lengthBytes<(1024^4)){
        Log.i("", 51 + " -- FILE INFO GB -- " + lengthBytes);
        lengthString = lengthBytes / (1024 ^ 3) + " GB";
        Log.i("", 52 + " -- FILE INFO GB -- " + lengthBytes);
    } else lengthString = "ERR";

    return lengthString;
}

它在应用程序ERR中显示了我。我想调试它，所以我添加了很多Log.i. logcat告诉我你可以在这句话下看到。

Logcat向我展示了这个：

06-30 11:50:23.523    1590-1590/info.myapplication15.app I/﹕ 1 -- FILE INFO -- 292303
06-30 11:50:24.253    1590-1590/info.myapplication15.app D/dalvikvm﹕ GC_FOR_ALLOC freed 99K, 5% free 3268K/3436K, paused 58ms, total 65ms
06-30 11:50:24.263    1590-1590/info.myapplication15.app I/dalvikvm-heap﹕ Grow heap (frag case) to 4.330MB for 1127536-byte allocation
06-30 11:50:24.443    1590-1599/info.myapplication15.app D/dalvikvm﹕ GC_FOR_ALLOC freed 6K, 4% free 4362K/4540K, paused 95ms, total 95ms
06-30 11:50:25.503    1590-1590/info.myapplication15.app W/Resources﹕ Converting to string: TypedValue{t=0x12/d=0x0 a=2 r=0x7f070040}
06-30 11:50:25.563    1590-1590/info.myapplication15.app W/Resources﹕ Converting to string: TypedValue{t=0x12/d=0x0 a=2 r=0x7f070041}
06-30 11:50:25.683    1590-1590/info.myapplication15.app W/Resources﹕ Converting to string: TypedValue{t=0x12/d=0x0 a=2 r=0x7f070042}
06-30 11:50:26.103    1590-1590/info.myapplication15.app W/Resources﹕ Converting to string: TypedValue{t=0x12/d=0x0 a=2 r=0x7f070040}
06-30 11:50:26.143    1590-1590/info.myapplication15.app W/Resources﹕ Converting to string: TypedValue{t=0x12/d=0x0 a=2 r=0x7f070041}
06-30 11:50:26.223    1590-1590/info.myapplication15.app W/Resources﹕ Converting to string: TypedValue{t=0x12/d=0x0 a=2 r=0x7f070042}
06-30 11:50:26.753    1590-1590/info.myapplication15.app I/Choreographer﹕ Skipped 180 frames!  The application may be doing too much work on its main thread.

我想用圆号和单位显示字符串。我读到我应该使用Math.round(i/1024)

我希望（文件长度为292303）显示：285.45 KB

Answer 1

只需使用以下代码：

  public String round(long unrounded) {
    BigDecimal bd = new BigDecimal(unrounded);
    BigDecimal rounded = bd.setScale(1, BigDecimal.ROUND_CEILING);
    return String.valueOf(rounded.longValue()) ;
  }

或者只使用Math.ceil()代替round() ..

编辑：只需使用我在下面提供的this link中接受的答案。

public static String humanReadableByteCount(long bytes, boolean si) {
 int unit = si ? 1000 : 1024;
 if (bytes < unit) return bytes + " B";
 int exp = (int) (Math.log(bytes) / Math.log(unit));
 String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp-1) + (si ? "" : "i");
 return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre);
}

如何将长数字舍入并在android中显示为字符串？

1 个答案: