当我运行我的应用程序时，它崩溃但我不知道为什么。 log cat正在给出致命的错误。
Logcat
09-30 07:09:38.380: D/AndroidRuntime(1361): Shutting down VM
09-30 07:09:38.380: W/dalvikvm(1361): threadid=1: thread exiting with uncaught exception (group=0xb4b06b90)
09-30 07:09:38.410: E/AndroidRuntime(1361): FATAL EXCEPTION: main
09-30 07:09:38.410: E/AndroidRuntime(1361): Process: shibli.sendDarood, PID: 1361
09-30 07:09:38.410: E/AndroidRuntime(1361): java.lang.RuntimeException: Unable to start activity ComponentInfo{shibli.sendDarood/shibli.sendDarood.MainActivity}: java.lang.NullPointerException
09-30 07:09:38.410: E/AndroidRuntime(1361): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2176)
09-30 07:09:38.410: E/AndroidRuntime(1361): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2226)
09-30 07:09:38.410: E/AndroidRuntime(1361): at android.app.ActivityThread.access$700(ActivityThread.java:135)
09-30 07:09:38.410: E/AndroidRuntime(1361): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1397)
09-30 07:09:38.410: E/AndroidRuntime(1361): at android.os.Handler.dispatchMessage(Handler.java:102)
09-30 07:09:38.410: E/AndroidRuntime(1361): at android.os.Looper.loop(Looper.java:137)
09-30 07:09:38.410: E/AndroidRuntime(1361): at android.app.ActivityThread.main(ActivityThread.java:4998)
09-30 07:09:38.410: E/AndroidRuntime(1361): at java.lang.reflect.Method.invokeNative(Native Method)
09-30 07:09:38.410: E/AndroidRuntime(1361): at java.lang.reflect.Method.invoke(Method.java:515)
09-30 07:09:38.410: E/AndroidRuntime(1361): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
09-30 07:09:38.410: E/AndroidRuntime(1361): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
09-30 07:09:38.410: E/AndroidRuntime(1361): at dalvik.system.NativeStart.main(Native Method)
09-30 07:09:38.410: E/AndroidRuntime(1361): Caused by: java.lang.NullPointerException
09-30 07:09:38.410: E/AndroidRuntime(1361): at shibli.sendDarood.MainActivity.onCreate(MainActivity.java:143)
09-30 07:09:38.410: E/AndroidRuntime(1361): at android.app.Activity.performCreate(Activity.java:5243)
09-30 07:09:38.410: E/AndroidRuntime(1361): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
09-30 07:09:38.410: E/AndroidRuntime(1361): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2140)
09-30 07:09:38.410: E/AndroidRuntime(1361): ... 11 more
09-30 07:14:39.150: I/Process(1361): Sending signal. PID: 1361 SIG: 9
码
package shibli.sendDarood;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.content.SharedPreferences;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends Activity {
EditText dAmnt;
TextView finmsg;
Button enter, msg, bt3;
int counter = 0;
long total = 0;
@Override
protected void onSaveInstanceState(Bundle outState) {
// TODO Auto-generated method stub
super.onSaveInstanceState(outState);
outState.putLong("Value", total);
}
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onRestoreInstanceState(savedInstanceState);
total=savedInstanceState.getLong("Value");
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
SharedPreferences ob=getSharedPreferences("mydata", Context.MODE_PRIVATE);
total=ob.getLong("Total", total);
setContentView(R.layout.activity_main);
finmsg = (TextView) findViewById(R.id.finalmsg);
dAmnt = (EditText) findViewById(R.id.editText1);
enter = (Button) findViewById(R.id.button1);
msg = (Button) findViewById(R.id.button2);
enter.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (dAmnt.getText().toString().equalsIgnoreCase("")) {
} else {
if (dAmnt.getText() != null
&& Integer.parseInt(dAmnt.getText().toString()) <= 1000) {
counter = Integer.parseInt(dAmnt.getText().toString());
total += counter;
dAmnt.getText().clear();
} else if (Integer.parseInt(dAmnt.getText().toString()) > 1000) {
finmsg.setText("hey Dude Plz Enter value Less than 1000");
dAmnt.getText().clear();
total += 0;
}
}
}
});
msg.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (total < 1) {
finmsg.setText("No Darood you have Recited Yet :" + total);
}
else if (total >= 1 && total <= 1000) {
finmsg.setText("Total Darood Shareef Recited :" + total);
}
else if (total > 1000) {
finmsg.setText("SubhanAllah !!SubhanAllah!!SubhanAllah!! ..Total Number of Darood you have Recited is: "+ total);
}
}
});
bt3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
total=0;
}
});
}
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
SharedPreferences ob=getSharedPreferences("mydata", Context.MODE_PRIVATE);
SharedPreferences.Editor ed= ob.edit();
ed.putLong("Total",total);
ed.commit();
}
}
xml代码
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/tvArabicText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:layout_margin="7dp"
android:gravity="center"
android:text="@string/arabicText"
android:textColor="#FF0707"
android:textStyle="bold"
/>
<TextView
android:id="@+id/tvEngText"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_below="@+id/tvArabicText"
android:layout_margin="7dp"
android:background="#00E00E"
android:gravity="center"
android:text="@string/engText"
/>
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_below="@+id/editText1"
android:layout_margin="7dp"
android:text="@string/submit" />
<TextView
android:id="@+id/finalmsg"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_below="@+id/button2"
android:layout_margin="7dp"
android:text="@string/FinalMsg"
android:textColor="#FF940A"
android:textSize="15sp" />
<EditText
android:id="@+id/editText1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:layout_margin="7dp"
android:ems="10"
android:hint="@string/hin"
android:inputType="number"
android:maxLength="7" >
</EditText>
<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_below="@+id/button1"
android:layout_margin="7dp"
android:text="@string/Button" />
<TextView
android:id="@+id/textView1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/tvEngText"
android:layout_below="@+id/tvEngText"
android:layout_margin="7dp"
android:background="#00E00E"
android:gravity="center"
android:text="@string/msg" />
</RelativeLayout>
我的清单文件是
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="shibli.sendDarood"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="19" />
<application
android:allowBackup="true"
android:icon="@drawable/gumbad_ekhizra"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="shibli.sendDarood.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>
</application>
</manifest>
答案 0 :(得分：3)
您需要在调用方法之前初始化bt3。
答案 1 :(得分：3)
由于以下原因，您的代码将崩溃：
此异常代码位于143行代码的MainActivity.java中。
快速修复：
Button bt3 = (Button) findViewById(R.id.button3);
您忘记在xml文件中设置此按钮。
<Button
android:id="@+id/button3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_below="@+id/button2"
android:layout_margin="7dp"
android:text="@string/Button" />
答案 2 :(得分：2)
我只能在布局文件中看到两个按钮。
但你已经宣布了三个按钮
public class MainActivity extends Activity {
EditText dAmnt;
TextView finmsg;
Button enter, msg, bt3; // three buttons
int counter = 0;
long total = 0;
setContentView(R.layout.activity_main);
finmsg = (TextView) findViewById(R.id.finalmsg);
dAmnt = (EditText) findViewById(R.id.editText1);
enter = (Button) findViewById(R.id.button1);
msg = (Button) findViewById(R.id.button2);
bt3 = (Button) findViewById(R.id.id_of_your_button) //Add this line
enter.setOnClickListener(new View.OnClickListener() {
答案 3 :(得分：0)
布局中只有2个按钮，首先在布局中创建第三个按钮然后 像其他人一样初始化该按钮。如果你没有初始化NPE来
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
SharedPreferences ob=getSharedPreferences("mydata", Context.MODE_PRIVATE);
total=ob.getLong("Total", total);
setContentView(R.layout.activity_main);
bt3=(Button)findViewById(R.id.xyz_button); //Here you find the new button
finmsg = (TextView) findViewById(R.id.finalmsg);
dAmnt = (EditText) findViewById(R.id.editText1);
enter = (Button) findViewById(R.id.button1);
msg = (Button) findViewById(R.id.button2);
enter.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (dAmnt.getText().toString().equalsIgnoreCase("")) {
} else {
if (dAmnt.getText() != null
&& Integer.parseInt(dAmnt.getText().toString()) <= 1000) {
counter = Integer.parseInt(dAmnt.getText().toString());
total += counter;
dAmnt.getText().clear();
} else if (Integer.parseInt(dAmnt.getText().toString()) > 1000) {
finmsg.setText("hey Dude Plz Enter value Less than 1000");
dAmnt.getText().clear();
total += 0;
}
}
}
});
msg.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (total < 1) {
finmsg.setText("No Darood you have Recited Yet :" + total);
}
else if (total >= 1 && total <= 1000) {
finmsg.setText("Total Darood Shareef Recited :" + total);
}
else if (total > 1000) {
finmsg.setText("SubhanAllah !!SubhanAllah!!SubhanAllah!! ..Total Number of Darood you have Recited is: "+ total);
}
}
});
bt3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
total=0;
}
});
}