Question

我是Android开发新手。这是给我的一项任务。我必须转换值，转换后的值必须显示在下一个活动中。但是当我按下提交按钮时，它崩溃了。我不知道是什么问题。我的RadioButtons有问题吗？请帮帮我......

这是第二个活动（ConvertActivity）

package com.gihan.temperatureconverter;

import android.content.Intent;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.RadioButton;




public class ConvertActivity extends ActionBarActivity {

//RadioButton cel=(RadioButton) findViewById(R.id.rCel);
//RadioButton fah=(RadioButton) findViewById(R.id.rFah);

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

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_convert, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

public void calculation(View view) {

    EditText val=(EditText) findViewById(R.id.editText);
    int value = Integer.valueOf(val.getText().toString()).intValue();
    int ans=0;
    int fahval=0;
    int celval=0;

    boolean checked = ((RadioButton) view).isChecked();

    switch(view.getId()) {
        case R.id.rCel:
            if (checked){
                ans=((value-32)*5/9);
                fahval=value;
                celval=ans;}
            break;
        case R.id.rFah:
            if (checked){
                ans=((value*9)/5)+32;
                celval=value;
                fahval=ans;}
            break;
    }


    /*if (cel.isChecked()){
        ans=((value-32)*5/9);
        fahval=value;
        celval=ans;
    }
    if (fah.isChecked()){
        ans=((value*9)/5)+32;
        celval=value;
        fahval=ans;
    }*/

    Intent intent = new Intent(ConvertActivity.this, LastActivity.class);
    intent.putExtra("celval", getText(celval));
    intent.putExtra("fahval", getText(fahval));
    ConvertActivity.this.startActivity(intent);

}
}

这是第二个XML（activity_convert）

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context="com.gihan.temperatureconverter.ConvertActivity"
android:background="@drawable/ic_background">

<EditText
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:inputType="numberDecimal"
    android:ems="10"
    android:id="@+id/editText"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_marginTop="50dp"
    android:hint="Enter Value"
    android:textSize="20dp"/>

<RadioGroup
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/radioGroup"
    android:layout_below="@+id/editText"
    android:layout_centerHorizontal="true">

    <RadioButton
        android:layout_width="200dp"
        android:layout_height="wrap_content"
        android:text="To Celsius"
        android:id="@+id/rCel"
        android:layout_below="@+id/editText"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="50dp"
        android:checked="false"
        android:gravity="fill_horizontal"
        android:textColor="#ffc80301"
        android:textSize="25sp"/>

    <RadioButton
        android:layout_width="200dp"
        android:layout_height="wrap_content"
        android:text="To Fahrenheit"
        android:id="@+id/rFah"
        android:checked="false"
        android:gravity="fill_horizontal"
        android:textColor="#ffc80301"
        android:textSize="25sp"
        android:layout_below="@+id/rCel"
        android:layout_alignLeft="@+id/rCel"
        android:layout_alignStart="@+id/rCel" />

</RadioGroup>

<Button
    android:layout_width="200dp"
    android:layout_height="wrap_content"
    android:text="Submit"
    android:id="@+id/sub"
    android:onClick="calculation"
    android:layout_below="@+id/radioGroup"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="80dp" />

</RelativeLayout>

这是第3项活动（LastActivity）

package com.gihan.temperatureconverter;


import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;


public class LastActivity extends ActionBarActivity {

TextView vFah=(TextView)findViewById(R.id.vFah);
TextView vCel=(TextView)findViewById(R.id.vCel);


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_last);//use whatever layout you want.

    Bundle extras = getIntent().getExtras();
    int celval=extras.getInt("celval");
    int fahval=extras.getInt("fahval");
    //String cel=String.valueOf(celval);
    //String fah=String.valueOf(fahval);
    vCel.setText(Integer.toString(celval));
    vFah.setText(Integer.toString(fahval));

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_convert, menu);
    return true;



}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

public void again(View view) {
    Intent intent = new Intent(LastActivity.this, ConvertActivity.class);
    LastActivity.this.startActivity(intent);
}

public void home(View view) {
    Intent intent = new Intent(LastActivity.this, MainActivity.class);
    LastActivity.this.startActivity(intent);
}
}

这是第3个XML（activity_last）

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/ic_background"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context="com.gihan.temperatureconverter.LastActivity">

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="Successfully Converted"
    android:id="@+id/textView2"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="30dp"
    android:textColor="#ffff0004"
    android:textSize="30sp"/>

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Home"
    android:id="@+id/button2"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true"
    android:layout_marginBottom="70dp"
    android:gravity="center_horizontal"
    android:textSize="25sp"
    android:onClick="home"/>

<Button
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Calculate again"
    android:id="@+id/button3"
    android:layout_marginBottom="45dp"
    android:gravity="center_horizontal"
    android:layout_above="@+id/button2"
    android:layout_centerHorizontal="true"
    android:textSize="25sp"
    android:onClick="again"/>

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="Fahrenheit"
    android:id="@+id/textView3"
    android:layout_below="@+id/textView2"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="30dp"
    android:textColor="#ff0010ff" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="Celsius"
    android:id="@+id/textView4"
    android:layout_below="@+id/textView3"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="52dp"
    android:textColor="#ff0010ff" />

<TextView
    android:layout_width="wrap_content"
    android:layout_height="20sp"
    android:id="@+id/vFah"
    android:layout_below="@+id/textView3"
    android:layout_centerHorizontal="true"
    android:textColor="#ff9300ff"/>

<TextView
    android:layout_width="wrap_content"
    android:layout_height="20sp"
    android:id="@+id/vCel"
    android:layout_below="@+id/textView4"
    android:layout_centerHorizontal="true"
    android:textColor="#ff9300ff"/>
</RelativeLayout>

的AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.gihan.temperatureconverter" >

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name=".MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity
        android:name=".ConvertActivity"
        android:label="@string/app_name">
    </activity>
    <activity
        android:name=".LastActivity"
        android:label="@string/app_name">
    </activity>
</application>

</manifest>

logcat的

 --------- beginning of crash
06-09 21:05:58.413    2381-2381/? E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.gihan.temperatureconverter, PID: 2381
java.lang.IllegalStateException: Could not execute method of the activity
        at android.view.View$1.onClick(View.java:4020)
        at android.view.View.performClick(View.java:4780)
        at android.view.View$PerformClick.run(View.java:19866)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5257)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
 Caused by: java.lang.reflect.InvocationTargetException
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at android.view.View$1.onClick(View.java:4015)
        at android.view.View.performClick(View.java:4780)
        at android.view.View$PerformClick.run(View.java:19866)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5257)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.ClassCastException: android.support.v7.widget.AppCompatButton cannot be cast to android.widget.RadioButton
        at com.gihan.temperatureconverter.ConvertActivity.calculation(ConvertActivity.java:56)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at android.view.View$1.onClick(View.java:4015)
        at android.view.View.performClick(View.java:4780)
        at android.view.View$PerformClick.run(View.java:19866)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5257)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

我尝试了一些评论。它也失败了。这也是Android Studio Project。

Answer 1

您的错误已解决检查此代码

mainactivity.java

public class MainActivity extends ActionBarActivity {

     EditText val;

       public static int ans;
       public static String fahval="";
       public static String celval="";

        RadioButton Box1,Box2;

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

        val =(EditText) findViewById(R.id.editText);   
    }



        public void calculation(View v)
        {


          //get value from edit text box and convert into double
          double a=Double.parseDouble(String.valueOf(val.getText()));

            Box1 = (RadioButton) findViewById(R.id.rCel);
            Box2 = (RadioButton) findViewById(R.id.rFah);


          //check which radio button is checked
          if(Box1.isChecked())
          {

          //display conversion

         celval = String.valueOf(f2c(a));
        // Toast.makeText(getApplicationContext(), celval,Toast.LENGTH_LONG).show();
          Box1.setChecked(true);
          }
          else
          {
                fahval = String.valueOf(c2f(a));
            //    Toast.makeText(getApplicationContext(), fahval,Toast.LENGTH_LONG).show();
                Box2.setChecked(true);
          }


           Intent intent = new Intent(this, LastActivity.class);
            intent.putExtra("celval", celval);
            intent.putExtra("fahval", fahval);

          startActivity(intent);

        } 


       //Celcius to Fahrenhiet method 
       private double c2f(double c)
       {
             return (c*9)/5+32;
       }
       //Fahrenhiet to Celcius method
       private double f2c(double f)
       {
             return (f-32)*5/9;
       }  


    }

LastActivity.java

public class LastActivity extends ActionBarActivity {

    TextView vFah;
    TextView vCel;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.last);//use whatever layout you want.

        vFah=(TextView)findViewById(R.id.vFah);
        vCel=(TextView)findViewById(R.id.vCel);

        Bundle extras = getIntent().getExtras();
        String  celval=extras.getString("celval");
        String fahval=extras.getString("fahval");
        //String cel=String.valueOf(celval);
        //String fah=String.valueOf(fahval);
        vCel.setText(celval);
        vFah.setText(fahval);

    }



    public void again(View view) {
        Intent intent = new Intent(LastActivity.this, MainActivity.class);
        LastActivity.this.startActivity(intent);
    }

    public void home(View view) {
        Intent intent = new Intent(LastActivity.this, MainActivity.class);
        LastActivity.this.startActivity(intent);
    }
}

Answer 2

本周我在构建一些应用程序，无法弄清楚为什么我无法从主要活动导航到第二个活动，再也无法从那里导航到第三级活动（该活动会弹出到第二个活动），我添加第三个时一直崩溃。最后，查看Logcat以找出问题所在，然后阅读“无法从'第二个活动'导航...。此视图将不接受导航”。搜索代码以查找错误，但从没想过要在那里查看。

应用程序不幸从第2次活动到第3次活动时停止

2 个答案: