复选框和AlerDialog

Question

我必须在Java警报中弹出一个对话框，以通知用户是否要删除广告，必须购买该应用程序的付费版本……我做了两个Java文件，还有一个叫做“对话”的文件，从中可以回忆起上面的内容文件和布局xml中定义的其他元素...问题是如果我放新对话框（this）会给我错误...而是当前通过单击复选框运行应用程序导致应用崩溃。崩溃后的复选框已经检查了，应该有......的复选框不能是可检查的。

package com.X.XX.XXX;


import android.app.AlertDialog;
import android.content.Context;

public class Dialogo {

    public static final int BUY = 1000;
    AlertDialog.Builder builder;

    public void mostra(int Id) {
        // TODO Auto-generated method stub
        switch(Id)
        {
        case BUY:
            builder.setTitle("Title");
            builder.setMessage("TEXT ");
            builder.setNegativeButton("CLOSE", null);
            builder.setPositiveButton("BUY", null);
            break;
        }
        builder.create().show();
    }

}

---

package com.X.XX;

import com.X.XX.XXX.Dialog;

import android.content.Intent;
import android.os.Bundle;
import android.preference.CheckBoxPreference;
import android.preference.Preference;
import android.preference.Preference.OnPreferenceClickListener;
import android.preference.PreferenceActivity;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.Toast;

public class Settings extends PreferenceActivity{

    CheckBoxPreference no_ads;
    Dialogo dialogo;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        this.addPreferencesFromResource(R.xml.settings);
        dialogo = new Dialogo(); 

        no_ads = (CheckBoxPreference) this.findPreference("no_ads");
        no_ads.setOnPreferenceClickListener(new OnPreferenceClickListener(){

            @Override
            public boolean onPreferenceClick(Preference preference) {
                // TODO Auto-generated method stub
                dialogo.mostra(Dialogo.BUY);
                ((CheckBoxPreference)preference).setChecked(false);
                return false;
            }});

    }

Answer 1

您必须先初始化构建器变量，然后再使用它。 因此，请确保将上下文也传递给您的函数，首先像这样声明它：

public void mostra(Context context, int Id) {
    builder = new AlertDialog.Builder(context);

然后这样称呼它：

dialogo.mostra(Settings.this, Dialogo.BUY);

完整的工作示例：

package com.X.XX.XXX;

import android.app.AlertDialog;
import android.content.Context;

public class Dialogo {
    public static final int BUY = 1000;

    public void mostra(Context context, int Id) {
        AlertDialog.Builder builder = new AlertDialog.Builder(context);
        // TODO Auto-generated method stub
        switch(Id)
        {
        case BUY:
            builder.setTitle("Title");
            builder.setMessage("TEXT ");
            builder.setNegativeButton("CLOSE", null);
            builder.setPositiveButton("BUY", null);
            break;
        }
        builder.create().show();
    }
}


package com.X.XX;
import com.X.XX.XXX.Dialog;
import android.content.Intent;
import android.os.Bundle;
import android.preference.CheckBoxPreference;
import android.preference.Preference;
import android.preference.Preference.OnPreferenceClickListener;
import android.preference.PreferenceActivity;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.Toast;

public class Settings extends PreferenceActivity{
    CheckBoxPreference no_ads;
    Dialogo dialogo;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        this.addPreferencesFromResource(R.xml.settings);
        dialogo = new Dialogo(); 

        no_ads = (CheckBoxPreference) this.findPreference("no_ads");
        no_ads.setOnPreferenceClickListener(new OnPreferenceClickListener(){
            @Override
            public boolean onPreferenceClick(Preference preference) {
                // TODO Auto-generated method stub
                dialogo.mostra(Settings.this, Dialogo.BUY);
                ((CheckBoxPreference)preference).setChecked(false);
                return false;
            }
        });
    }
}