自定义对话框 Android 的问题

Question

我的应用中有一个自定义对话框，但在实现所需行为时遇到了问题。我的对话框有 4 个按钮。 （返回、有效、修改和恢复）。当用户单击修改或有效时，我想调用另一个活动。所以我正在使用 Intent 但它崩溃了。

错误日志：

05-19 13:29:21.495: 错误/调试标签（974）： java.lang.NullPointerException 05-19 13:29:21.495：错误/调试标签（974）：
在 android.content.ComponentName.(ComponentName.java:75) 05-19 13:29:21.495: 错误/调试标签（974）：在 android.content.Intent.(Intent.java:2551) 05-19 13:29:21.495: 错误/调试标签（974）：在 com.android.booztermobile.activity.HeaderMailDisplayActivity.onClick(HeaderMailDisplayActivity.java:571) 05-19 13:29:21.495: 错误/调试标签（974）：在 android.view.View.performClick(View.java:2364) 05-19 13:29:21.495: 错误/调试标签（974）：在 android.view.View.onTouchEvent(View.java:4179) 05-19 13:29:21.495: 错误/调试标签（974）：在 android.widget.TextView.onTouchEvent(TextView.java:6540) 05-19 13:29:21.495: 错误/调试标签（974）：在 android.view.View.dispatchTouchEvent(View.java:3709) 05-19 13:29:21.495: 错误/调试标签（974）：在 android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 05-19 13:29:21.495: 错误/调试标签（974）：在 android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 05-19 13:29:21.495: 错误/调试标签（974）：在 android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 05-19 13:29:21.495: 错误/调试标签（974）：在 android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 05-19 13:29:21.495: 错误/调试标签（974）：在 android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 05-19 13:29:21.495: 错误/调试标签（974）：在 android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884) 05-19 13:29:21.495: 错误/调试标签（974）：在 com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1659) 05-19 13:29:21.495: 错误/调试标签（974）：在 com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1107) 05-19 13:29:21.495: 错误/调试标签（974）：在 android.app.Dialog.dispatchTouchEvent(Dialog.java:643) 05-19 13:29:21.495: 错误/调试标签（974）：在 com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1643) 05-19 13:29:21.495: 错误/调试标签（974）：在 android.view.ViewRoot.handleMessage(ViewRoot.java:1691) 05-19 13:29:21.495: 错误/调试标签（974）：在 android.os.Handler.dispatchMessage(Handler.java:99) 05-19 13:29:21.495: 错误/调试标签（974）：在 android.os.Looper.loop(Looper.java:123) 05-19 13:29:21.495: 错误/调试标签（974）：在 android.app.ActivityThread.main(ActivityThread.java:4363) 05-19 13:29:21.495: 错误/调试标签（974）：在 java.lang.reflect.Method.invokeNative(Native 方法) 05-19 13:29:21.495: 错误/调试标签（974）：在 java.lang.reflect.Method.invoke(Method.java:521) 05-19 13:29:21.495: 错误/调试标签（974）：在 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 05-19 13:29:21.495: 错误/调试标签（974）：在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 05-19 13:29:21.495: 错误/调试标签（974）：在 dalvik.system.NativeStart.main(Native 方法）

我的自定义对话框：

package com.android.booztermobile.services;

import com.android.booztermobile.R;

import android.app.Dialog;
import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.widget.Button;


public class MailDialog extends Dialog {

    private Button btnValid;
    private Button btnBack;
    private Button btnRestore;
    private Button btnModify;
    private Context context;


    public MailDialog(Context cont) {
        super(cont);
        context = cont;
        }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.d("TestApp", "Dialog created");
            setContentView(R.layout.dialog_classement);     

            btnValid = (Button) findViewById(R.id.btnValidClassement);
            btnBack = (Button) findViewById(R.id.btnBackClassement);    
            btnRestore = (Button) findViewById(R.id.btnRestoreClassement);
            btnModify = (Button) findViewById(R.id.btnModifyClassement);

    }
}

和活动（因为太长而被剪掉）：

        //create dialog
 public void getMailInformations(View v, Context context){

  currentMail = (MailHeader) v.getTag();

  dial = new MailDialog(context);

  dial.setTitle("Classement");
  dial.show();

  btnValidClassement = (Button) dial.findViewById(R.id.btnValidClassement);
  btnValidClassement.setOnClickListener(this);

 }

/** Onclick : */

    public void onClick(View view) {

//THIS WORKS (Activity Button)
    if (view == lblPreviousMails) {

            positionList -= 20;
            // create Intent
            Intent defineIntentDisplayPreviousMails = new Intent(HeaderMailDisplayActivity.this, HeaderMailDisplayActivity.class);

            //Create bundle to pass informations to the other activity
            Bundle objetbundle = new Bundle();
            objetbundle.putString("positionList", String.valueOf(positionList));
            objetbundle.putStringArrayList("currentMails", seqnumList);
            objetbundle.putString("uidh", uidh);
            defineIntentDisplayPreviousMails.putExtras(objetbundle);

            // call headermailDisplayActivity
            HeaderMailDisplayActivity.this.startActivity(defineIntentDisplayPreviousMails);

        }

//THIS DOESN'T WORKS (Dialog Button)
    if(view == btnValidClassement){

   try{

    ClassementHandlerCall classement = new               ClassementHandlerCall();
       boolean mailClassify = classement.classifyMail(AuthentificationActivity.uidh, 
         String.valueOf(currentMail.getSeqnum()), null, null);

       dial.dismiss();

       if (mailClassify == true){

                //create Intent 
                Intent defineIntentClassifyMails = new Intent(MailClassificationActivity.this, HeaderMailDisplayActivity.class);

                // Object that allows to pass person's uidh and positionList onto HeaderMailDisplayActivity
                Bundle objetbundle = new Bundle();
                objetbundle.putString("uidh",uidh);
                objetbundle.putString("positionList", String.valueOf(positionList));
                defineIntentClassifyMails.putExtras(objetbundle);

                // call HeaderMailDisplayActivity 
                MailClassificationActivity.this.startActivity(defineIntentClassifyMails);


       }

   }catch(Exception e){
    // TODO Auto-generated catch block
    Log.e("DEBUGTAG","Error occured", e);
    e.printStackTrace();
   }



  }

}

Answer 1

根据堆栈跟踪，您似乎正在使用一些格式错误的参数调用 Intent 构造函数。

Answer 2

要从意图开始活动，您需要在清单 xml 文件中添加带有此代码的活动

<activity android:name=".youractivityname"
          android:configChanges="keyboardHidden|orientation"
          android:label="@string/app_name">
</activity>

将代码放在清单中的应用程序关闭标记之前。
而按钮点击事件中的代码是：

Intent myIntent = new Intent(v.getContext(), youractivity.class);
startActivityForResult(myIntent, 1);