我想知道如何防止数学运算符重复。
例如，这是我得到的9+++++****----////
有什么办法可以防止手术重复吗？非常感谢你的帮助。
下面是我的代码：

public class MyActivity extends AppCompatActivity implements View.OnClickListener {

    Button button_clear, button_addition, button_dot, button_multiply,button_divide,button_subtract,
    button_one,button_two,button_three,button_four,button_five,button_six,button_seven,button_eight,
            button_nine,
    button_zero,button_equal;

    TextView displayTv, result;

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

        displayTv=findViewById(R.id.displayTV);
        result=findViewById(R.id.answerCalculated);

        asignId(button_clear, R.id.clear);
        asignId(button_addition, R.id.addition);
        asignId(button_subtract, R.id.subtract);
        asignId(button_multiply, R.id.multiplication);
        asignId(button_divide, R.id.divide);
        asignId(button_dot, R.id.dot);
        asignId(button_one, R.id.button_one);
        asignId(button_two, R.id.button_two);
        asignId(button_three, R.id.button_three);
        asignId(button_four, R.id.button_four);
        asignId(button_five, R.id.button_five);
        asignId(button_six, R.id.button_six);
        asignId(button_seven, R.id.button_seven);
        asignId(button_eight, R.id.button_eight);
        asignId(button_nine, R.id.button_nine);
        asignId(button_zero, R.id.button_zero);
        asignId(button_equal,R.id.button_equal);
    }

    private void asignId(Button btn, int id) {
        btn=findViewById(id);
        btn.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {

        //set view to button

        Button button=(Button)view;

        //get buttonText
        String buttonText=button.getText().toString();

        //get DisplayedText
        String displayedText=displayTv.getText().toString();

        //displayed text plus button text
        displayedText=displayedText+buttonText;

        displayTv.setText(displayedText);

        String finalResult=getResult(displayedText);

        switch (view.getId()){

            case R.id.clear:
                displayTv.setText("");
                result.setText("0");
                break;

            case R.id.button_equal:
                if(!finalResult.equals("ERR")){
                    result.setText(finalResult);

                }
        }


        //

    }

    private String getResult(String data) {
        try{
            Context context  = Context.enter();
            context.setOptimizationLevel(-1);
            Scriptable scriptable = context.initStandardObjects();
            String finalResult =  context.evaluateString(scriptable,data,"Javascript",1,null).toString();
            if(finalResult.endsWith(".0")){
                finalResult = finalResult.replace(".0","");
            }
            return finalResult;
        }catch (Exception e){
            return "Err";
        }

    }
}

我发现这个答案与我的相似，但不同的是他们使用Kotlin而我使用Java。