单击按钮时，应用程序崩溃，Android Studio（Java）

-4

Hello fellow programmers! 
I have a very disturbing situation here...I'm developing an Android App with several activities.In them I have buttons.The app itself is for measuring calories and other sports releated stuff. 
I have a calorie calculator which I have built in the app,spread across 2 activities.In activity 1,the calculator measures the Basal Metabolic Rate and In the second activity,the app calculates the calories needed,when clicking a button for the desired activity level.My app crashes in the second activity,when clicking "Sedentary" button and I have no clue why,because these buttons are built just like the buttons in my first activity.I'll post photos and my code so you can get orientation. 
Btw,the app crashes also when clicking "Null Data" in the first activity with the BMR...The button doesn't have any coding on it and does nothing.I'm not calling calculate() method in the second activity,instead I tried doing the button click in the main method,but it still didn't work.

您好同事！我有一个非常令人不安的情况在这里...我正在开发一个Android应用程序与几个活动。在他们我有按钮。该应用程序本身是测量卡路里和其他运动相关的东西。我有一个卡路里计算器，我已经在应用程序中构建，分布在2个活动中。在活动1中，计算器测量基础代谢率，在第二个活动中，应用程序计算需要的卡路里，单击所需的按钮活动水平。我的应用程序在第二项活动中崩溃，点击“久坐”按钮时，我不知道为什么，因为这些按钮的内容与我第一次活动中的按钮一样。我会发布照片和代码，以便您可以获得方向。顺便说一句，应用程序也崩溃时，第一个活动与BMR中单击“空数据”...该按钮没有任何编码，并且什么都不做。我没有在第二个活动中调用calculate（）方法，而是我尝试在主方法中按下按钮，但它仍然无法工作。 First Activity Second Activity 单击按钮时，应用程序崩溃，Android Studio（Java）

`package com.petartonkov.foodandsportsinfo; 

import android.content.Intent; 
import android.os.Bundle; 
import android.os.Parcelable; 
import android.support.v7.app.AppCompatActivity; 
import android.support.v7.widget.Toolbar; 
import android.view.View; 
import android.widget.Button; 
import android.widget.CheckBox; 
import android.widget.EditText; 
import android.widget.TextView; 

public class CalorieCalculator extends AppCompatActivity { 

    public Button nextstepbtn; 
    public TextView BMR; 
    public EditText height; 
    public EditText weight; 
    public EditText age; 

    public void calculate() { 
     final Button calculateBMR = (Button) findViewById(R.id.CalcBtn); 
     final TextView BMR = (TextView) findViewById(R.id.textView_BMR); 
     final EditText weight = (EditText) findViewById(R.id.editText_weight); 
     final EditText height = (EditText) findViewById(R.id.editText_height); 
     final EditText age = (EditText) findViewById(R.id.editText_age); 
     assert calculateBMR != null; 
     calculateBMR.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       assert weight != null; 
       float weight1 = Float.parseFloat(weight.getText().toString()); 
       assert height != null; 
       float height1 = Float.parseFloat(height.getText().toString()); 
       assert age != null; 
       float age1 = Float.parseFloat(age.getText().toString()); 
       float BMR1 = (13.75f * weight1 + 5.003f * height1 - 6.755f * age1) + 66.75f; 
       assert BMR != null; 
       BMR.setText(Float.toString(BMR1)); 
      } 
     }); 
    } 
    public void calculate1() { 
     final Button calculateBMR = (Button) findViewById(R.id.CalcBtnFemale); 
     final TextView BMR = (TextView) findViewById(R.id.textView_BMR); 
     final EditText weight = (EditText) findViewById(R.id.editText_weight); 
     final EditText height = (EditText) findViewById(R.id.editText_height); 
     final EditText age = (EditText) findViewById(R.id.editText_age); 
     assert calculateBMR != null; 
     calculateBMR.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       assert weight != null; 
       float weight1 = Float.parseFloat(weight.getText().toString()); 
       assert height != null; 
       float height1 = Float.parseFloat(height.getText().toString()); 
       assert age != null; 
       float age1 = Float.parseFloat(age.getText().toString()); 
       float BMR1 = (9.563f * weight1 + 1.85f * height1 - 4.676f * age1) + 655.1f; 
       assert BMR != null; 
       BMR.setText(Float.toString(BMR1)); 
      } 
     }); 
    } 
    public void init4(){ 
     nextstepbtn = (Button)findViewById(R.id.NextStepBtn); 
     nextstepbtn.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       Intent intent1 = new Intent(getBaseContext(), CalorieCalculatorSecondActivity.class); 
       intent1.putExtra("BMR", (Parcelable) BMR); 
       startActivity(intent1); 
      } 
     }); 


    } 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_calorie_calculator); 
     Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
     setSupportActionBar(toolbar); 
      init4(); 
calculate(); 
     calculate1(); 
    } 

} 
` 

     ` package com.petartonkov.foodandsportsinfo; 

    import android.os.Bundle; 
    import android.support.design.widget.FloatingActionButton; 
    import android.support.design.widget.Snackbar; 
    import android.support.v7.app.AppCompatActivity; 
    import android.support.v7.widget.Toolbar; 
    import android.view.View; 
    import android.widget.Button; 
    import android.widget.TextView; 

    public class CalorieCalculatorSecondActivity extends CalorieCalculator { 

    public void totalcalories() { 
     final Button calculateBtn = (Button) findViewById(R.id.button_sedentary); 
     final TextView totalcalories = (TextView) findViewById(R.id.textView_totalcalories); 
     final TextView BMR = (TextView) findViewById(R.id.textView_BMR); 
     assert calculateBtn != null; 
     calculateBtn.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       assert BMR != null; 
       float BMR2 = Float.parseFloat(BMR.getText().toString()); 
       float totalcalories1 = BMR2 * 1.2f; 
       assert totalcalories != null; 
       totalcalories.setText(Float.toString(totalcalories1)); 
      } 
     }); 
    } 
     public void onCreate(Bundle savedInstanceState) { 
      super.onCreate(savedInstanceState); 
      setContentView(R.layout.activity_calorie_calculator_second); 
      Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
      setSupportActionBar(toolbar); 
      Bundle extras = getIntent().getExtras(); 
    final Button calcBtn = (Button)findViewById(R.id.button_sedentary); 
      final TextView totalcalories2 = (TextView)findViewById(R.id.textView_totalcalories); 
      final TextView BMR1 = (TextView) findViewById(R.id.textView_BMR); 
      assert calcBtn != null; 
      calcBtn.setOnClickListener(new View.OnClickListener() { 
       @Override 
       public void onClick(View v) { 
        assert BMR1 != null; 
        float BMR3 = Float.parseFloat(BMR1.getText().toString()); 
        float totalcalories4 = BMR3 * 1.2f; 
        assert totalcalories2 != null; 
        totalcalories2.setText(Float.toString(totalcalories4)); 
       } 
      }); 
     } 
    } 
`

<TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:textAppearance="?android:attr/textAppearanceMedium" 
     android:text="Enter your data below to calculate your BMR(Basal Metabolic Rate) and then enter your level of physical activity to determine your daily calorie needs.BMR-this number is the calories needed from the body to maintain basic living functions." 
     android:id="@+id/textView2" 
     android:textColor="#040404" 
     android:layout_alignParentTop="true" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" 
     android:layout_marginTop="30dp" /> 

    <Button 
     style="?android:attr/buttonStyleSmall" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="go to next step" 
     android:id="@+id/NextStepBtn" 
     android:layout_alignParentBottom="true" 
     android:layout_centerHorizontal="true" /> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:textAppearance="?android:attr/textAppearanceMedium" 
     android:text="BMR:" 
     android:id="@+id/textView11" 
     android:textColor="#070707" 
     android:layout_below="@+id/CalcBtn" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" 
     android:layout_marginTop="26dp" /> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:textAppearance="?android:attr/textAppearanceMedium" 
     android:text="CAL" 
     android:id="@+id/textView13" 
     android:layout_alignTop="@+id/textView_BMR" 
     android:layout_centerHorizontal="true" 
     android:textColor="#980606" /> 

    <Button 
     style="?android:attr/buttonStyleSmall" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="NULL DATA" 
     android:id="@+id/btn_nulldata" 
     android:layout_alignBaseline="@+id/NextStepBtn" 
     android:layout_alignBottom="@+id/NextStepBtn" 
     android:layout_alignRight="@+id/textView2" 
     android:layout_alignEnd="@+id/textView2" 
     android:onClick="onCheckboxClicked"/> 


    <EditText 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:inputType="numberDecimal" 
     android:ems="10" 
     android:id="@+id/editText_age" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" 
     android:layout_marginTop="27dp" 
     android:hint="Enter age" 
     android:layout_below="@+id/textView2" /> 

    <EditText 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:inputType="numberDecimal" 
     android:ems="10" 
     android:id="@+id/editText_weight" 
     android:layout_below="@+id/editText_age" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" 
     android:hint="Enter weight(In KG)" 
     android:layout_alignRight="@+id/NextStepBtn" 
     android:layout_alignEnd="@+id/NextStepBtn" /> 

    <EditText 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:inputType="numberDecimal" 
     android:ems="10" 
     android:id="@+id/editText_height" 
     android:layout_below="@+id/editText_weight" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" 
     android:hint="Enter height(In CM)" /> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:textAppearance="?android:attr/textAppearanceMedium" 
     android:id="@+id/textView_BMR" 
     android:layout_alignTop="@+id/textView11" 
     android:layout_toLeftOf="@+id/NextStepBtn" 
     android:layout_toStartOf="@+id/NextStepBtn" 
     android:textColor="#980606" /> 

    <Button 
     style="?android:attr/buttonStyleSmall" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="CALCULATE BMR-MALE" 
     android:id="@+id/CalcBtn" 
     android:background="?attr/colorPrimary" 
     android:textColor="#ffffff" 
     android:layout_marginTop="31dp" 
     android:layout_below="@+id/editText_height" 
     android:layout_toLeftOf="@+id/textView13" 
     android:layout_toStartOf="@+id/textView13" /> 

    <Button 
     style="?android:attr/buttonStyleSmall" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="CALCULATE BMR-FEMALE" 
     android:id="@+id/CalcBtnFemale" 
     android:background="?attr/colorPrimary" 
     android:textColor="#ffffff" 
     android:layout_alignBottom="@+id/CalcBtn" 
     android:layout_toRightOf="@+id/textView13" 
     android:layout_toEndOf="@+id/textView13" /> 


</RelativeLayout>`

<TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:textAppearance="?android:attr/textAppearanceMedium" 
     android:text="SELECT YOUR LEVEL OF PHYSICAL ACTIVITY:" 
     android:id="@+id/textView10" 
     android:layout_alignParentTop="true" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" /> 

    <Button 
     style="?android:attr/buttonStyleSmall" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="sedentary" 
     android:id="@+id/button_sedentary" 
     android:layout_below="@+id/textView10" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" 
     android:clickable="true" 
     android:enabled="true" 
     android:onClick="setContentView" /> 

    <Button 
     style="?android:attr/buttonStyleSmall" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="moderately active" 
     android:id="@+id/button_moderatelyactive" 
     android:layout_alignTop="@+id/button_sedentary" 
     android:layout_alignRight="@+id/textView14" 
     android:layout_alignEnd="@+id/textView14" /> 

    <Button 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="Very active" 
     android:id="@+id/button_veryactive" 
     android:layout_below="@+id/button_sedentary" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" /> 

    <Button 
     style="?android:attr/buttonStyleSmall" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="Extremely active" 
     android:id="@+id/button_extremelyactive" 
     android:layout_alignBottom="@+id/button_veryactive" 
     android:layout_alignLeft="@+id/button_moderatelyactive" 
     android:layout_alignStart="@+id/button_moderatelyactive" /> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:textAppearance="?android:attr/textAppearanceSmall" 
     android:text="Sedentary - Little or no exercise,little walking" 
     android:id="@+id/textView14" 
     android:layout_below="@+id/button_veryactive" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" 
     android:textColor="#e10e0e" /> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:textAppearance="?android:attr/textAppearanceSmall" 
     android:text="Lighty active - light exercise 1-3 times/week + walking" 
     android:id="@+id/textView15" 
     android:layout_below="@+id/textView14" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" 
     android:textColor="#e10e0e" /> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:textAppearance="?android:attr/textAppearanceSmall" 
     android:text="Moderately active - exercise 3-5 times/week + walking" 
     android:id="@+id/textView16" 
     android:layout_below="@+id/textView15" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" 
     android:textColor="#e10e0e" /> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:textAppearance="?android:attr/textAppearanceSmall" 
     android:text="Very active - hard exercise 5-7 times/week + walking" 
     android:id="@+id/textView17" 
     android:textColor="#e10e0e" 
     android:layout_below="@+id/textView16" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" /> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:textAppearance="?android:attr/textAppearanceMedium" 
     android:text="TOTAL CALORIES NEEDED:" 
     android:id="@+id/textView18" 
     android:layout_centerVertical="true" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" 
     android:textColor="#080808" /> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:textAppearance="?android:attr/textAppearanceMedium" 
     android:id="@+id/textView_totalcalories" 
     android:layout_alignTop="@+id/textView18" 
     android:layout_toRightOf="@+id/textView18" 
     android:layout_toEndOf="@+id/textView18" 
     android:editable="false" 
     android:enabled="false" 
     android:text="0" /> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:textAppearance="?android:attr/textAppearanceMedium" 
     android:text="CAL" 
     android:id="@+id/textView20" 
     android:layout_alignBottom="@+id/textView_totalcalories" 
     android:layout_alignParentRight="true" 
     android:layout_alignParentEnd="true" 
     android:textColor="#090909" /> 

    <Button 
     style="?android:attr/buttonStyleSmall" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="NULL DATA" 
     android:id="@+id/btn_nulldata2" 
     android:layout_marginBottom="48dp" 
     android:layout_alignParentBottom="true" 
     android:layout_alignRight="@+id/button_sedentary" 
     android:layout_alignEnd="@+id/button_sedentary" /> 

    <TextView 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:textAppearance="?android:attr/textAppearanceSmall" 
     android:text="Extra active - hard exercise 5-7 times/week + physical job + walking" 
     android:id="@+id/textView3" 
     android:textColor="#e10e0e" 
     android:layout_below="@+id/textView17" 
     android:layout_alignParentLeft="true" 
     android:layout_alignParentStart="true" /> 

    <Button 
     style="?android:attr/buttonStyleSmall" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="Lightly active" 
     android:id="@+id/button" 
     android:layout_alignBottom="@+id/button_extremelyactive" 
     android:layout_alignParentRight="true" 
     android:layout_alignParentEnd="true" 
     android:layout_toRightOf="@+id/button_extremelyactive" 
     android:layout_toEndOf="@+id/button_extremelyactive" /> 

</RelativeLayout>`

                    --------- beginning of crash 
06-14 06:10:35.167 2481-2481/com.petartonkov.foodandsportsinfo E/AndroidRuntime: FATAL EXCEPTION: main 
                       Process: com.petartonkov.foodandsportsinfo, PID: 2481 
                       java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.CharSequence android.widget.TextView.getText()' on a null object reference 
                        at com.petartonkov.foodandsportsinfo.CalorieCalculatorSecondActivity$2.onClick(CalorieCalculatorSecondActivity.java:44) 
                        at android.view.View.performClick(View.java:5198) 
                        at android.view.View$PerformClick.run(View.java:21147) 
                        at android.os.Handler.handleCallback(Handler.java:739) 
                        at android.os.Handler.dispatchMessage(Handler.java:95) 
                        at android.os.Looper.loop(Looper.java:148) 
                        at android.app.ActivityThread.main(ActivityThread.java:5417) 
                        at java.lang.reflect.Method.invoke(Native Method) 
                        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
                        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

来源

2016-06-13 П. Т.

发布你的logcat，并为将来的问题阅读[this]（http://stackoverflow.com/help/formatting）和[this]（http://stackoverflow.com/help/how-to-ask） –

我会记住它的.logcat是在崩溃时发布的。 –

哪个班正在使用1st布局和2nd布局？哪一个是activity_calorie_calculator_second – NehaK

这梅托德抛出

 calcBtn.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       assert BMR1 != null; 
       float BMR3 = Float.parseFloat(BMR1.getText().toString()); 
       float totalcalories4 = BMR3 * 1.2f; 
       assert totalcalories2 != null; 
       totalcalories2.setText(Float.toString(totalcalories4)); 
      } 
     });

你没有的TextView（BMR1）与textView_BMR的ID在你secondActivity布局

来源

2016-06-14 07:06:21

错误是，当我在第二个activity中调用我的对象时，它是null。它告诉我它是null。但是在第一个activity中它不是null，而是它显示你的BMR的Textview。如何在第二个活动中获得它，所以它不是null？ –

您是否想要从第二项活动中访问第一项活动中的视图？ –

Yes.But Android Studio允许我这样做，例如。访问第二个活动中的所有文字浏览。 –

从一个活动传递值到另一个可以使用意图额外

意图额外是您想要从一个活动传递到另一个活动的一系列附加信息。您可以创建额外这样

//First Activity 
Intent i = new Intent(FirstActiviy.this, SecondActivity.class); 
String value = "some string you want to put in the extra"; 
int value2 = 14 

//put extra as key-value pairs 
i.putExtra("KEY", value); 
i.putExtra("KEY2", value2); 

startActivity(i); 


//Second activity 

//Get the values from previous Activity by keys you set 
String stringValueFromPreviousActivity = getIntent().getStringExtra("key"); 

//Note: when you getting integer as the second parameter pass the default value if there is no passed integer 
int intValueFromPreviousActiviy = getIntent().getIntExtra("key",4);

来源

2016-06-15 10:48:23

我试图在一个活动设置计算器......我rearanged按钮和猜测什么......？我从浮TextView的BMR为NULL，g虽然我在BMR字符串TextView.Why是否发生这种情况？我在第一个活动中用另一种方法编写了总卡路里的代码。

public void calculatetotalcalories() 
    { 
     final Button calcbtn_sedentary = (Button)findViewById(R.id.button_sedentary); 
     final TextView totalcalories = (TextView)findViewById(R.id.textView_totalcalories); 
     calcbtn_sedentary.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       float BMRconverted= Float.parseFloat(String.valueOf(BMR)); 
       float totalcalories1 =BMRconverted*1.2f; 
       totalcalories.setText(Float.toString(totalcalories1)); 
      } 
     });

来源

2016-06-15 20:06:52

我解决了这个问题。它在活动开始时是一个空对象引用。现在所有的东西都可以工作！

来源

2016-06-20 19:33:51

单击按钮时，应用程序崩溃，Android Studio（Java）

回答

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