java - 我该如何解决这个 "Method invocation ' bundle.getString ("Ans_age").equals(R.string.age2 )' may produce ' java.lang.NullPointerException'"

Question

为什么我总是在 if else 语句中收到此消息:方法调用 'bundle.getString("Ans_phy").equals(R.string.active)' 可能会产生 'java.lang.NullPointerException'

我的提交按钮也不起作用，因为它假设在我单击提交按钮后在下一个 Activity 中显示“新体重”和“卡路里”。

评论.java

public void setBtnSubmit()
{
    //Create a bundle object to store the bundle added to the intent
    final Bundle bundle = getIntent().getExtras();

    //Get the values out by key
    final String umur = bundle.getString("Ans_age");
    final String textBMI = bundle.getString("Ans_bmi");
    final String aktiviti = bundle.getString("Ans_phy");

final String textCategory = bundle.getString("Ans_category");

    final String txtcf = bundle.getString("cfDisease");

    //Get the textview controls
    final TextView txtage = (TextView) findViewById(R.id.textView5);
    final TextView txtbmi = (TextView) findViewById(R.id.textView7);
    final TextView txtphy = (TextView) findViewById(R.id.textView6);

final TextView txtcategory = (TextView) findViewById(R.id.result);

    //final TextView cf_result = (TextView) findViewById(R.id.result);

    //Button buttonSend = (Button) findViewById(R.id.btnsend);

    //Set the text values of the text controls
    txtage.setText(umur);
    txtbmi.setText(textBMI);
    txtphy.setText(aktiviti);

txtcategory.setText(textCategory);

    //cf_result.setText(txtcf);

    Button btnsubmit = (Button) findViewById(R.id.btnsubmit);
    //Intent intentsubmit = new Intent();

    //intentsubmit.setClass(Review.this, Result.class);
    btnsubmit.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            //startActivity(intentsubmit);

            Integer calories;
            double weight1, weight2, weight3;
            double newWeight;

            // AGE 41 - 45
            if (bundle.getString("Ans_age").equals(R.string.age1)) // 41 - 45
            {
                weight1 = 0.7;
                if (bundle.getString("Ans_phy").equals(R.string.moderate)) //Sedentary Active
                {
                    weight2 = 0.8;
                    if ((txtcategory.equals("Underweight"))) //Underweight
                    {
                        weight3 = 0.6;
                        newWeight = 0.8 * weight2;
                        calories = 1600;

                        String cf = Double.toString(newWeight);
                        String cal = Integer.toString(calories);


                        Intent intent = new Intent(Review.this, Result.class);
                        Bundle bundle = new Bundle();

                        bundle.putString("Ans_calories", cal);
                        bundle.putString("cfCalories", cf);

                        intent.putExtras(bundle);
                        startActivity(intent);
                    }
                }
            }
            else
            if (bundle.getString("Ans_age").equals(R.string.age2)) // 46 - 50
            {
                weight1 = 0.7;
                if (bundle.getString("Ans_phy").equals(R.string.active)) // Moderately Active
                {
                    weight2 = 0.7;
                    if ((txtcategory.equals("Normal"))) // Underweight
                    {
                        weight3 = 0.8;
                        newWeight = 0.9 * weight1;
                        calories = 1800;

                        String cf = Double.toString(newWeight);
                        String cal = Integer.toString(calories);


                        Intent intent = new Intent(Review.this, Result.class);
                        Bundle bundle = new Bundle();

                        bundle.putString("Ans_calories", cal);
                        bundle.putString("cfCalories", cf);

                        intent.putExtras(bundle);
                        startActivity(intent);
                    }
                }
            }
            else
            if (bundle.getString("Ans_age").equals(R.string.age2)) // 41 - 45
            {
                weight1 = 0.8;
                if (bundle.getString("Ans_phy").equals(R.string.moderate)) // Active
                {
                    weight2 = 0.8;
                    if ((txtcategory.equals("Obese"))) // Underweight
                    {
                        weight3 = 0.8;
                        newWeight = 0.9 * weight3;
                        calories = 2000;

                        String cf = Double.toString(newWeight);
                        String cal = Integer.toString(calories);


                        Intent intent = new Intent(Review.this, Result.class);
                        Bundle bundle = new Bundle();

                        bundle.putString("Ans_calories", cal);
                        bundle.putString("cfCalories", cf);

                        intent.putExtras(bundle);
                        startActivity(intent);
                    }
                }
            }

        }
    });
}

结果.java

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

    Intent intent = getIntent();
    final String cal = intent.getStringExtra("Ans_calories");
    final String cf = intent.getStringExtra("cfCalories");

    final TextView kalori = (TextView) findViewById(R.id.show_calories);
    final TextView keputusan = (TextView) findViewById(R.id.show_result);

    kalori.setText(cal);
    keputusan.setText(cf);
}

Answer 1

您可以执行以下操作以从 Intent 获取数据:

Bundle extras = getIntent().getExtras();
        if (extras != null) {
            String yourStirng = extras.getString("yourKeyString");
        }

当尝试将数据用于 Intent 时，您也可以这样做:

 Intent intent = new Intent(getActivity() / this ,YourActivity.class);
        intent.putExtra("YOURKEyString", "Your value string");
        startActivity(intent);

试试这个，希望对你有帮助