我从eclipse切换到android studio，我正在尝试向我的清单文件添加一个活动，我不知道我应该使用的代码，我的应用程序一直在崩溃继承我的清单中的代码
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="penis.jason.payday" >
<application
android:allowBackup="true"
android:icon="@drawable/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="settings"
android:label="Pay Day!!">
</activity>
<activity android:name="statistics"
android:label="Pay Day!!">
</activity>
</application>
我所做的是当用户按下设置按钮而不是该类和新的xml时。下面是我用来发送意图的代码
Settings.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent GoToSettings = new Intent(getApplicationContext(), settings.class);
startActivity(GoToSettings);
finish();
}
});
继承我的logcat
08-24 10:41:52.098 21750-21750/penis.jason.payday E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: penis.jason.payday, PID: 21750
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{penis.jason.payday/penis.jason.payday.settings}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2259)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2392)
at android.app.ActivityThread.access$900(ActivityThread.java:169)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1280)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:146)
at android.app.ActivityThread.main(ActivityThread.java:5487)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1283)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1099)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at android.app.Activity.findViewById(Activity.java:1986)
at penis.jason.payday.settings.<init>(settings.java:23)
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1208)
at android.app.Instrumentation.newActivity(Instrumentation.java:1067)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2250)
这是整个设置类
package penis.jason.payday;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.CheckBox;
import java.util.Calendar;
@SuppressWarnings("unused")
public class settings extends Activity {
boolean FullScreen;
Button SaveAndExit = (Button) findViewById(R.id.SaveAndExit);
Button Save = (Button) findViewById(R.id.Save);
Button Cls = (Button) findViewById(R.id.Cls);
CheckBox FullScreenOnOff = (CheckBox) findViewById(R.id.fullScreen);
CheckBox SaveWarningOnOff = (CheckBox) findViewById(R.id.SaveWarningOnOff);
Calendar cal = Calendar.getInstance();
int year = cal.get(Calendar.YEAR);
int month= cal.get(Calendar.MONTH)+1;
int day = cal.get(Calendar.DATE);
String FullDate = (" "+month+"/"+day+"/"+year);
String Date=(String.valueOf(FullDate));
@Override
protected void onCreate(Bundle saveInstanceState){
super.onCreate(saveInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.settings);
FullScreen = getSharedPreferences("Settings",MODE_PRIVATE).getBoolean("FullScreen",false);
if(FullScreen==true){
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.settings);
}
SaveAndExit.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent GoToMain = new Intent(getApplicationContext(), MainActivity.class);
startActivity(GoToMain);
finish();
}
});
Save.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
}
});
Cls.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
}
});
if(FullScreenOnOff.isChecked()){
FullScreen = true;
SharedPreferences FullScreenSave = getSharedPreferences("Settings", Context.MODE_PRIVATE);
SharedPreferences.Editor FullScreenE = FullScreenSave.edit();
FullScreenE.putBoolean("FullScreen", FullScreen);
FullScreenE.commit();
}
}
}
_______ UPDATE ______ 我发现了问题！
我不得不改变我宣布按钮变换的方式
boolean FullScreen;
Button SaveAndExit,Save,Cls;
CheckBox FullScreenOnOff,SaveWarningOnOff;
Calendar cal = Calendar.getInstance();
int year = cal.get(Calendar.YEAR);
int month= cal.get(Calendar.MONTH)+1;
int day = cal.get(Calendar.DATE);
String FullDate = (" "+month+"/"+day+"/"+year);
String Date=(String.valueOf(FullDate));
@Override
protected void onCreate(Bundle saveInstanceState){
super.onCreate(saveInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.settings);
FullScreen = getSharedPreferences("Settings",MODE_PRIVATE).getBoolean("FullScreen",false);
if(FullScreen==true){
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.settings);
}
SaveAndExit = (Button) findViewById(R.id.SaveAndExit);
Save = (Button) findViewById(R.id.Save);
Cls = (Button) findViewById(R.id.Cls);
FullScreenOnOff = (CheckBox) findViewById(R.id.fullScreen);
SaveWarningOnOff = (CheckBox) findViewById(R.id.SaveWarningOnOff);
}
答案 0 :(得分：1)
从类名的外观来看，它应该如下所示，大小写非常重要。
<activity android:name=".Settings"
android:label="Pay Day!!">
</activity>
<activity android:name=".Statistics"
android:label="Pay Day!!">
</activity>
答案 1 :(得分：0)
在清单中声明<uses-sdk android:minSdkVersion="minimum_integer_value" android:targetSdkVersion="your_target_integer_value" />。可能是您尝试使用较高级别的API