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数字とボタン用に5つのテキスト編集があります。ボタンがクリックされると、アプリは空のままにしたフィールドに基づいて別の方程式を計算します。ただし、複数のフィールドを空のままにしておくと、最初の if ステートメントの最初の double が無効であるというエラーが表示され、アプリがクラッシュし続けます。

コードの考え方

if (first field.getText().toString().equals("")) {...}
else if (second field.getText().toString().equals("")) {...}
else if (third field.getText().toString().equals("")) {...}
else if (fourth field.getText().toString().equals("")) {...}
else if (fifth.getText().toString().equals("")) {...}
else {...}

基本的に、最後のものは、上記のいずれでもない場合に乾杯する必要があります（2〜5個の空、0個の空

実際の構文は次のとおりです。

    calc.setOnClickListener(new OnClickListener() {         
            public void onClick(View v) {
                EditText fv = (EditText) findViewById(R.id.pv_fv);
                EditText pv = (EditText) findViewById(R.id.pv_pv);
                EditText r = (EditText) findViewById(R.id.pv_discountrate);
                EditText n = (EditText) findViewById(R.id.pv_periods);
                EditText t = (EditText) findViewById(R.id.pv_years);



                if (fv.getText().toString().equals("")) {
                    double r1 = Double.parseDouble(r.getText().toString());
                    double n1 = Double.parseDouble(n.getText().toString());
                    double t1 = Double.parseDouble(t.getText().toString());
                    double pv1 = Double.parseDouble(pv.getText().toString());
                    double answer1 = pv1*(Math.pow(1+(r1/n1) ,n1*t1 ));
                    answer1 = (double)(Math.round(answer1*100))/100;
                    TextView answer = (TextView) findViewById(R.id.pv_answer);
                    answer.setText("The Future Value of the cash flow is: "+answer1);
                }

                else if (pv.getText().toString().equals("")) {
                    double fv1 = Double.parseDouble(fv.getText().toString());
                    double r1 = Double.parseDouble(r.getText().toString());
                    double n1 = Double.parseDouble(n.getText().toString());
                    double t1 = Double.parseDouble(t.getText().toString());
                    double answer1 = fv1/(Math.pow(1+(r1/n1) ,n1*t1 ));
                    answer1 = (double)(Math.round(answer1*100))/100;
                    TextView answer = (TextView) findViewById(R.id.pv_answer);
                    answer.setText("The Present Value of the cash flow is: "+answer1);                      
                }

                else if (r.getText().toString().equals("")){
                    double fv1 = Double.parseDouble(fv.getText().toString());
                    double pv1 = Double.parseDouble(pv.getText().toString());
                    double n1 = Double.parseDouble(n.getText().toString());
                    double t1 = Double.parseDouble(t.getText().toString());
                    double answer1 = ( (Math.pow(fv1/pv1, 1/(n1*t1) ) ) -1)*n1 ;
                    answer1 = (double)(Math.round(answer1*100))/100;
                    TextView answer = (TextView) findViewById(R.id.pv_answer);
                    answer.setText("The discount rate / interest rate applied is: "+answer1);
                }

                else if (t.getText().toString().equals("")){
                    double fv1 = Double.parseDouble(fv.getText().toString());
                    double pv1 = Double.parseDouble(pv.getText().toString());
                    double n1 = Double.parseDouble(n.getText().toString());
                    double r1 = Double.parseDouble(r.getText().toString());
                    double answer1 = Math.log(fv1/pv1) / (n1* Math.log(1+(r1/n1) ) ) ;
                    answer1 = (double)(Math.round(answer1*100))/100;
                    TextView answer = (TextView) findViewById(R.id.pv_answer);
                    answer.setText("The number of years is: "+answer1);
                }

                else if(n.getText().toString().equals("")){
                    Toast errormsg = Toast.makeText(PresentValue.this, "Sorry but Number of Periods cannot be computed.", 5000);
                    errormsg.setGravity(Gravity.CENTER, 0, 0);
                    errormsg.show();
                }

                else {
                    Toast errormsg = Toast.makeText(PresentValue.this, "You either left too many fields empty or filled all of them.", 5000);
                    errormsg.setGravity(Gravity.CENTER, 0, 0);
                    errormsg.show();
                }

            }           
        });

これの何が問題なのですか？

4

3 に答える 3

1

Assuming you have only these five fields - the else statement is reachable only if none of the fields are empty.

If only one is empty, it will be caught by the relevant if statement - it works fine in this aspect.
If two ore more are empty - it will be caught only once, in the first if condition that applies - which seems not to be what you want.
If none are empty - the else statement will be reached, though none are empty - this is obviously what you meant for.

An alternative approach could be not using the else if statements, but only ifs, and count the number of faults. If it is higher then 1 - multiple fields are empty. If it is 0 - no fields are empty. If it can be applied is of course dependent on the actual content of the blocks for each statement.

于 2012-05-10T20:17:58.523 に答える
0

これが私がそれを解決した方法です。しかし、それは本当に...息苦しいようです。それをもっと見苦しくする方法はありますか？

//clickhandler
        calc.setOnClickListener(new OnClickListener() {         
            public void onClick(View v) {
                EditText fv = (EditText) findViewById(R.id.pv_fv);
                EditText pv = (EditText) findViewById(R.id.pv_pv);
                EditText r = (EditText) findViewById(R.id.pv_discountrate);
                EditText n = (EditText) findViewById(R.id.pv_periods);
                EditText t = (EditText) findViewById(R.id.pv_years);
                TextView answer = (TextView) findViewById(R.id.pv_answer);
                int filledfields = 0;

                if (fv.getText().toString().equals("")){
                    filledfields ++;
                }
                if (pv.getText().toString().equals("")) {
                    filledfields ++;
                }
                if (r.getText().toString().equals("")) {
                    filledfields ++;
                }
                if (t.getText().toString().equals("")) {
                    filledfields ++;
                }
                if (n.getText().toString().equals("")) {
                    filledfields ++;
                }

                if (filledfields > 1){
                    Toast errormsg = Toast.makeText(PresentValue.this, "Sorry but you left more than one field empty.", 5000);
                    errormsg.setGravity(Gravity.CENTER, 0, 0);
                    errormsg.show();
                }

                else if (fv.getText().toString().equals("")) {
                    double r1 = Double.parseDouble(r.getText().toString());
                    double n1 = Double.parseDouble(n.getText().toString());
                    double t1 = Double.parseDouble(t.getText().toString());
                    double pv1 = Double.parseDouble(pv.getText().toString());
                    double answer1 = pv1*(Math.pow(1+(r1/n1) ,n1*t1 ));
                    answer1 = (double)(Math.round(answer1*100))/100;

                    answer.setText("The Future Value of the cash flow is: "+answer1);
                }

                else if (pv.getText().toString().equals("")) {
                    double fv1 = Double.parseDouble(fv.getText().toString());
                    double r1 = Double.parseDouble(r.getText().toString());
                    double n1 = Double.parseDouble(n.getText().toString());
                    double t1 = Double.parseDouble(t.getText().toString());
                    double answer1 = fv1/(Math.pow(1+(r1/n1) ,n1*t1 ));
                    answer1 = (double)(Math.round(answer1*100))/100;

                    answer.setText("The Present Value of the cash flow is: "+answer1);                      
                }

                else if (r.getText().toString().equals("")){
                    double fv1 = Double.parseDouble(fv.getText().toString());
                    double pv1 = Double.parseDouble(pv.getText().toString());
                    double n1 = Double.parseDouble(n.getText().toString());
                    double t1 = Double.parseDouble(t.getText().toString());
                    double answer1 = ( (Math.pow(fv1/pv1, 1/(n1*t1) ) ) -1)*n1 ;
                    answer1 = (double)(Math.round(answer1*100))/100;

                    answer.setText("The discount rate / interest rate applied is: "+answer1);
                }

                else if (t.getText().toString().equals("")){
                    double fv1 = Double.parseDouble(fv.getText().toString());
                    double pv1 = Double.parseDouble(pv.getText().toString());
                    double n1 = Double.parseDouble(n.getText().toString());
                    double r1 = Double.parseDouble(r.getText().toString());
                    double answer1 = Math.log(fv1/pv1) / (n1* Math.log(1+(r1/n1) ) ) ;
                    answer1 = (double)(Math.round(answer1*100))/100;

                    answer.setText("The number of years is: "+answer1);
                }

                else if(n.getText().toString().equals("")){
                    Toast errormsg = Toast.makeText(PresentValue.this, "Sorry but Number of Periods cannot be computed.", 5000);
                    errormsg.setGravity(Gravity.CENTER, 0, 0);
                    errormsg.show();
                }

                else {
                    Toast errormsg = Toast.makeText(PresentValue.this, "You either left too many fields empty or filled all of them.", 5000);
                    errormsg.setGravity(Gravity.CENTER, 0, 0);
                    errormsg.show();
                }

            }           
        });
        //clickhandler end
于 2012-05-14T01:23:52.867 に答える
0

フィールドへの名前または参照をまたはに入れListますSet。その後、必要な空のものを簡単に取得できます。

と

if (emptyFieldSet.size() > 1) {
    toast that says "error multiples are empty"
}

elsesの落書きの後の最後のステートメントよりもはるかに読みやすくなっていifます。

于 2012-05-10T20:31:18.030 に答える