我如何在 exp4j 编译器中定义 Ln java

Question

我正在制作 android 计算器，所以我想在 exp4j 编译器中定义 Ln (2.303*Math.log10(number))：http://www.objecthunter.net/exp4j/

但我不想手动输入数字所有操作都存储在字符串结果中所以我想在你看到Ln做这个操作的时候告诉编译器(2.303*Math.log10(number))

String txt = txt_Screen.getText().toString();


    try {
        // Calculate the result and display
       // if(txt.contains("ln")) {
         //   txt.replace("ln",)
        Expression expression = new ExpressionBuilder(txt).build();
        double result = expression.evaluate();
        if ((result == Math.floor(result)) && !Double.isInfinite(result)) {


            result_Screen.setText((int) result + "");
        }else
            result_Screen.setText(result+"");


       // double result = expression.evaluate();



    } catch (Exception ex) {
        txt_Screen.setText("Syntax Error");

    }

Answer 1

    String txt = txt_Screen.getText().toString();


try {
    // Calculate the result and display
   // if(txt.contains("ln")) {
     //   txt.replace("ln",)

 **Function ln = new Function("ln", 1) {
 @Override
 public double apply(double... args) {
    return 2.303*Math.log10(args[0]);
 }
 };**
    Expression expression = new 
ExpressionBuilder(txt).**function(ln)**.build();
    double result = expression.evaluate();
    if ((result == Math.floor(result)) && !Double.isInfinite(result)) {


        result_Screen.setText((int) result + "");
    }else
        result_Screen.setText(result+"");


   // double result = expression.evaluate();



} catch (Exception ex) {
    txt_Screen.setText("Syntax Error");

}

我如何在 exp4j 编译器中定义 Ln java

How I can define Ln in exp4j compiler java

android

calculator