如何将带有空格的双精度数字符串更改为可以使用的双精度数组

Question

我是编码新手，因此我们将不胜感激。我在安卓手机上有一个文本文件，其中包含几个基本上是数字的字符串块 - “553955765.50 272 272 272 200.1 100 7391 22 22 10 53”

我已经设法从手机中读取了文件，但是每次我尝试将这个数字字符串转换为双精度数组时，我都会收到一条错误消息

java.lang.NumberFormatException：无效的双精度：“553955765.50 272 272 272 200.1 100 7391 22 22 10 53”

这是我的代码块；任何帮助将不胜感激 - 我对编码还是很陌生，所以如果你能解释解决方案，我将永远感激不尽！

public class MainActivity extends AppCompatActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    File sdcard = Environment.getExternalStorageDirectory();
    ArrayList aList = new ArrayList();

    //Get the text file
    File file = new File(sdcard, "test.txt");

    //Read text from file
    StringBuilder text = new StringBuilder();

    try {
        BufferedReader br = new BufferedReader(new FileReader(file));
        String line;

        while ((line = br.readLine()) != null) {

            String[] tokens = line.split(" ");
            double[] ary = new double[tokens.length];
            for (int n = 0; n < tokens.length; n++){

                ary[n] = Double.parseDouble(tokens[n]);
            }
        }
        br.close();
    } catch (IOException e) {

    }

    //Find the view by its id
    TextView tv = (TextView) findViewById(R.id.text_view);

//Set the text
    tv.setText(text.toString());
    }
}

这是完整的错误：

FATAL EXCEPTION: main
Process: usd.read_text, PID: 32434                                                          java.lang.RuntimeException: Unable to start activity ComponentInfo{usd.read_text/usd.read_text.MainActivity}: java.lang.NumberFormatException: Invalid double: "553955765.50    272 272 272 200.1   100 7391    22  22  10  53"

at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2521)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2595)
at android.app.ActivityThread.access$800(ActivityThread.java:178)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1470)
at android.os.Handler.dispatchMessage(Handler.java:111)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5631)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:959)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:754)
Caused by: java.lang.NumberFormatException: Invalid double: "553955765.50   272 272 272 200.1   100 7391    22  22  10  53"
at java.lang.StringToReal.invalidReal(StringToReal.java:63)
at java.lang.StringToReal.initialParse(StringToReal.java:164)
at java.lang.StringToReal.parseDouble(StringToReal.java:282)
at java.lang.Double.parseDouble(Double.java:301)
at usd.read_text.MainActivity.onCreate(MainActivity.java:43)
at android.app.Activity.performCreate(Activity.java:6092)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1112)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2468)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2595) 
at android.app.ActivityThread.access$800(ActivityThread.java:178) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1470) 
at android.os.Handler.dispatchMessage(Handler.java:111) 
at android.os.Looper.loop(Looper.java:194) 
at android.app.ActivityThread.main(ActivityThread.java:5631) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 

Answer 1

假设空格后的每个数字都是双精度数，您必须使用split() 分隔字符串数组中的数字。之后，在 split() 生成的数组的每个项目中使用 Double.parseDouble()。