E/AndroidRuntime(15518): FATAL EXCEPTION: main
E/AndroidRuntime(15518): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.cydeon.plasmamodz/com.cydeon.plasmamodz.Boots}: java.lang.NullPointerException
E/AndroidRuntime(15518): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2224)
E/AndroidRuntime(15518): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2358)
E/AndroidRuntime(15518): at android.app.ActivityThread.access$600(ActivityThread.java:154)
E/AndroidRuntime(15518): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1248)
E/AndroidRuntime(15518): at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(15518): at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime(15518): at android.app.ActivityThread.main(ActivityThread.java:5235)
E/AndroidRuntime(15518): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(15518): at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime(15518): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795)
E/AndroidRuntime(15518): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562)
E/AndroidRuntime(15518): at dalvik.system.NativeStart.main(Native Method)
E/AndroidRuntime(15518): Caused by: java.lang.NullPointerException
E/AndroidRuntime(15518): at android.app.Activity.findViewById(Activity.java:1839)
E/AndroidRuntime(15518): at com.cydeon.plasmamodz.Boots.<init>(Boots.java:47)
E/AndroidRuntime(15518): at java.lang.Class.newInstanceImpl(Native Method)
E/AndroidRuntime(15518): at java.lang.Class.newInstance(Class.java:1319)
E/AndroidRuntime(15518): at android.app.Instrumentation.newActivity(Instrumentation.java:1054)
E/AndroidRuntime(15518): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2215)
E/AndroidRuntime(15518): ... 11 more
这个话题很困惑。让我解释。在我的应用程序中，仅一个部分就有 70 多个按钮。我有很多不同的部分。现在，每个按钮都使用相同的布局，因此每个按钮都会启动相同的 Activity ，这样我就不会创建 70 个单独的类。现在，在这个新类中，它必须显示与所选 bugton 相对应的图像并下载文件(当单击某个按钮时)。所以，基本上，我需要某种方法来识别另一个类中的这些按钮，并说“如果按下按钮 x，则显示图像 y，如果按下按钮 y，则显示图像 x。类似地，如果按下按钮 x，则下载文件y，如果按下按钮 y，则下载文件 x，等等。我只是不知道如何判断在上一个类中按下了哪个按钮。我真的需要这方面的帮助。我已经工作了 2 周，这已经让我停下来，我找不到答案。这并不是真正依赖于代码，我将在整个应用程序中多次使用此方法，所以我认为不需要发布任何代码。再次，重申我的问题，多个按钮启动同一个 Activity 。在该 Activity 中，我需要根据上一课中按下的按钮执行操作。谢谢。:)
编辑:这是一些代码...
BootFragment.java:
package com.cydeon.plasmamodz;
import java.io.File;
import java.io.IOException;
import java.util.concurrent.TimeoutException;
import com.stericson.RootTools.RootTools;
import com.stericson.RootTools.exceptions.RootDeniedException;
import com.stericson.RootTools.execution.CommandCapture;
import android.app.Fragment;
import android.content.Intent;
import android.os.Bundle;
import android.os.Environment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
public class BootFragment extends Fragment {{
//Defining File Directory
File directory = new File(Environment.getExternalStorageDirectory() + "/plasma/boot");
if(directory.exists() && directory.isDirectory()){
//Do nothing. Directory is existent
}else{
//Directory does not exist. Make directory (First time app users)
directory.mkdirs();
}
File bkup = new File(Environment.getExternalStorageDirectory() + "/plasma/boot/bkup");
if(bkup.exists() && bkup.isDirectory()){
//Do nothing. Directory is existent
}else{
//Directory does not exist. Make directory (First time app users)
bkup.mkdirs();
}}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.boot_frag,
container, false);
Button Ablue = (Button) view.findViewById(R.id.bABlue);
Button AblueR = (Button) view.findViewById(R.id.bABlueR);
Button Abokeh = (Button) view.findViewById(R.id.bAbokeh);
Ablue.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
Intent b = new Intent(getActivity(), Boots.class);
b.putExtra("Dragon", R.id.bABlue);
BootFragment.this.startActivity(b);
}
});
AblueR.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
Intent c = new Intent(getActivity(), Boots.class);
c.putExtra("Xbox", R.id.bABlueR);
BootFragment.this.startActivity(c);
}
});
Abokeh.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
Intent d = new Intent(getActivity(), Boots.class);
d.putExtra("GameB", R.id.bAbokeh);
BootFragment.this.startActivity(d);
}
});
return view;
}}
Boots.java:
package com.cydeon.plasmamodz;
import com.stericson.RootTools.*;
import com.stericson.RootTools.exceptions.RootDeniedException;
import com.stericson.RootTools.execution.CommandCapture;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.Reader;
import java.net.URL;
import java.net.URLConnection;
import java.util.List;
import java.util.concurrent.TimeoutException;
import com.cydeon.plasmamodz.R;
import android.app.ActionBar;
import android.app.Activity;
import android.app.DownloadManager;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
//Class for Boot Animation Blue Kindle
public class Boots extends Activity {
public static String TAG = "Boots";
Process process;
private class DownloadFile extends AsyncTask<String, Integer, String>{
@Override
protected String doInBackground(String... sURL) {
try{
URL url = new URL(sURL[0]);
URLConnection connection = url.openConnection();
connection.connect();
//Shows 0-100% progress bar
int fileLength = connection.getContentLength();
//Download the file
InputStream input = new BufferedInputStream(url.openStream());
OutputStream output = new FileOutputStream("/sdcard/plasma/boot/b..ootanimation.zip");
byte data[] = new byte[1024];
long total = 0;
int count;
while ((count = input.read(data)) != -1) {
total += count;
//Publish the Progress
publishProgress((int) (total * 100/fileLength));
output.write(data, 0, count);
}
output.flush();
output.close();
input.close();
} catch (Exception e) {
}
return null;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
mProgressDialog.show();
}
@Override
protected void onProgressUpdate(Integer... progress){
super.onProgressUpdate(progress);
mProgressDialog.setProgress(progress[0]);
}
@Override
protected void onPostExecute(String result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
mProgressDialog.dismiss();
Context context = getApplicationContext();
CharSequence text = "Installing. Please Wait";
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
if (RootTools.isBusyboxAvailable()){
RootTools.remount("/system", "rw");
CommandCapture command = new CommandCapture(0, "su", "sh /sdcard/plasma/scripts/boots.sh");
try {
RootTools.getShell(true).add(command).waitForFinish();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (TimeoutException e) {
e.printStackTrace();
} catch (RootDeniedException e) {
e.printStackTrace();
}
} else {
RootTools.offerBusyBox(Boots.this);
}
}
}
ProgressDialog mProgressDialog;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.boots);
ActionBar actionBar = getActionBar();
actionBar.hide();
ImageView img = (ImageView) findViewById(R.id.iv2);
img.setImageResource(R.drawable.boot1);
Button install = (Button) findViewById(R.id.bAInstall);
Button rtrn = (Button) findViewById(R.id.bAReturn);
mProgressDialog = new ProgressDialog(Boots.this);
mProgressDialog.setMessage("Downloading..." );
mProgressDialog.setIndeterminate(false);
mProgressDialog.setMax(100);
mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
install.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
TextView creator = (TextView) findViewById(R.id.tvCreate);
Intent bootI = getIntent();
int dball = getIntent().getExtras().getInt("Dragon", -1);
int xbox = getIntent().getExtras().getInt("Xbox", -1);
int GameB = getIntent().getExtras().getInt("GameB", 1);
if (dball != -1){
DownloadFile downloadFile = new DownloadFile();
downloadFile.execute("http:\\correspondingurl");
creator.setText("Dragon Ball");
}if (xbox != -1){
DownloadFile downloadFile = new DownloadFile();
downloadFile.execute("http:\\correspondingurl");
creator.setText("Xbox");
}if (GameB != -1){
DownloadFile downloadFile = new DownloadFile();
downloadFile.execute("http:\\correspondingurl");
creator.setText("GameBoy");
}
}
}
);
rtrn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
finish();
}
});
}
}
我尝试过很多不同的方法。这是我的最新尝试。它们都不起作用。
猫日志:看顶部...
最佳答案
通过 Intent.putExtra() 将所需信息传递给 Intent 中的新 Activity (参见http://developer.android.com/reference/android/content/Intent.html)
关于java - Android - 按钮 : Receiving through data through intents/other methods，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/15214139/