Java从文本文件中读取值

我是 Java 新手。我有一个包含以下内容的文本文件。

`trace` -
structure(
 list(
  "a" = structure(c(0.748701,0.243802,0.227221,0.752231,0.261118,0.263976,1.19737,0.22047,0.222584,0.835411)),
  "b" = structure(c(1.4019,0.486955,-0.127144,0.642778,0.379787,-0.105249,1.0063,0.613083,-0.165703,0.695775))
 )
)
    

现在我想要的是，我需要将“a”和“b”作为两个不同的数组列表。

您需要逐行读取文件。它是用一个完成的BufferedReader像这样 ：

try {
    FileInputStream fstream = new FileInputStream("input.txt");
    BufferedReader br = new BufferedReader(new InputStreamReader(fstream));
    String strLine;         
    int lineNumber = 0;
    double [] a = null;
    double [] b = null;
    // Read File Line By Line
    while ((strLine = br.readLine()) != null) {
        lineNumber++;
        if( lineNumber == 4 ){
            a = getDoubleArray(strLine);
        }else if( lineNumber == 5 ){
            b = getDoubleArray(strLine);
        }               
    }
    // Close the input stream
    in.close();
    //print the contents of a
    for(int i = 0; i < a.length; i++){
        System.out.println("a["+i+"] = "+a[i]);
    }           
} catch (Exception e) {// Catch exception if any
    System.err.println("Error: " + e.getMessage());
}

假设你的"a" and"b"位于文件的第四行和第五行，当满足这些行时，您需要调用一个方法，该方法将返回一个数组double :

private static double[] getDoubleArray(String strLine) {
    double[] a;
    String[] split = strLine.split("[,)]"); //split the line at the ',' and ')' characters
    a = new double[split.length-1];
    for(int i = 0; i < a.length; i++){
        a[i] = Double.parseDouble(split[i+1]); //get the double value of the String
    }
    return a;
}

希望这可以帮助。我仍然强烈推荐阅读 JavaI/O and String教程。