AlertDialog用EditText強制關閉

Question

我得到了錯誤：

E/AndroidRuntime: FATAL EXCEPTION: main
              Process: com.crmdev.circuitorlcparalelo, PID: 6778
              java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.Integer.intValue()' on a null object reference
                  at com.crmdev.circuitorlcparalelo.MainActivity$3.onClick(MainActivity.java:70)
                  at android.support.v7.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)
                  at android.os.Handler.dispatchMessage(Handler.java:106)
                  at android.os.Looper.loop(Looper.java:164)
                  at android.app.ActivityThread.main(ActivityThread.java:6626)
                  at java.lang.reflect.Method.invoke(Native Method)
                  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:811)

對於帶有AlertDialog的以下代碼：

AlertDialog.Builder result = new AlertDialog.Builder(MainActivity.this);
        result.setTitle("Iterações");
        result.setMessage("Digite o número de iterações desejadas: ");
        final EditText iteracoes = new EditText(this);
        iteracoes.setInputType(InputType.TYPE_CLASS_NUMBER);
        iteracoes.setGravity(9);
        iteracoes.setPadding(10,10,10,10);
        result.setView(iteracoes);
        result.setPositiveButton("Calcular", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                if(iteracoes.getText().equals("")){
                    Toast.makeText(getApplicationContext(), "Digite algum valor para as iterações!", Toast.LENGTH_LONG).show();
                    iteracoes.setText("");
                }
                else{
                    //Pega o numero de iterações
                    iteracao = Integer.getInteger(iteracoes.getText().toString());

                    tensaof = onCalculo(iteracao);

                    Bundle dad = new Bundle();
                    dad.putDouble("resultado", tensaof);
                    Intent intent = new Intent(MainActivity.this, ResultActivity.class);
                    intent.putExtras(dad);
                    startActivity(intent);
                }
            }
        });
        result.show();

每次我按一下Calcular申請人的“強制關閉”按鈕時，我都會更改onCalculo函數，但會以相同的方式繼續。 當函數onCalculo僅更改TextView時 ，應用程序沒有此問題。 我看不到出了什么問題。 謝謝。

Answer 1

因為您使用錯誤的方法將String解析為Integer 。 你應該

iteracao = Integer.parseInt(iteracoes.getText().toString());

代替

iteracao = Integer.getInteger(iteracoes.getText().toString());

順便說一句， parseInt方法可能會引發NumberFormatException因此您應該放入try/catch塊中，以防止應用程序崩潰。

Integer iteracao = null;
try {
    iteracao = Integer.parseInt(iteracoes.getText().toString());
} catch (NumberFormatException e) {
    // TODO: Show a toast to let users know the input value is not valid
}