我正在使用gridI，onItemClickListener打开一个对话框，但是我在对话框中得到了一个NPE，我无法弄清楚如何解决它。非常感谢！
这是我的Galerie.java：
package com.descoper.rom;
import java.util.ArrayList;
import android.os.Bundle;
import android.app.Activity;
import android.app.Dialog;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.GridView;
import android.widget.ListAdapter;
import android.widget.TextView;
import android.widget.Toast;
public class Galerie extends Activity {
GridView gridView;
ArrayList<Item> gridArray = new ArrayList<Item>();
GalerieAdapter customGridAdapter;
private Dialog dialog;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.galerie);
//set grid view item
Bitmap homeIcon = BitmapFactory.decodeResource(this.getResources(), R.drawable.ro);
Bitmap userIcon = BitmapFactory.decodeResource(this.getResources(), R.drawable.ro);
gridArray.add(new Item(homeIcon,"Home"));
gridArray.add(new Item(userIcon,"User"));
gridArray.add(new Item(homeIcon,"House"));
gridArray.add(new Item(userIcon,"Friend"));
gridArray.add(new Item(homeIcon,"Home"));
gridArray.add(new Item(userIcon,"Personal"));
gridArray.add(new Item(homeIcon,"Home"));
gridArray.add(new Item(userIcon,"User"));
gridArray.add(new Item(homeIcon,"Building"));
gridArray.add(new Item(userIcon,"User"));
gridArray.add(new Item(homeIcon,"Home"));
gridArray.add(new Item(userIcon,"xyz"));
gridView = (GridView) findViewById(R.id.gridView1);
customGridAdapter = new GalerieAdapter(this, R.layout.galerie_row, gridArray);
gridView.setAdapter((ListAdapter) customGridAdapter);
gridView.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
if(position == 0){
dialog = new Dialog(getApplicationContext());
dialog.setContentView(R.layout.dialog1);
dialog.setTitle(position);
TextView text = (TextView) dialog.findViewById(R.id.textView1);
Button btnSave = (Button) dialog.findViewById(R.id.button1);
btnSave.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
dialog.dismiss();
}
});
dialog.show();
}
if(position == 1){
Toast.makeText(Galerie.this, "APASATAAAAAAA" + position, Toast.LENGTH_SHORT).show();
}
if(position ==2){
Toast.makeText(Galerie.this, "APASATAAAAAAA" + position, Toast.LENGTH_SHORT).show();
}
}
});
}
}
dialog1.xml：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="TextView" />
<Button
android:id="@+id/button1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Button" />
</LinearLayout>
logcat的：
04-29 15:38:59.614: E/AndroidRuntime(1272): FATAL EXCEPTION: main
04-29 15:38:59.614: E/AndroidRuntime(1272): Process: com.descoper.rom, PID: 1272
04-29 15:38:59.614: E/AndroidRuntime(1272): java.lang.NullPointerException
04-29 15:38:59.614: E/AndroidRuntime(1272): at android.app.Dialog.<init>(Dialog.java:156)
04-29 15:38:59.614: E/AndroidRuntime(1272): at android.app.Dialog.<init>(Dialog.java:133)
04-29 15:38:59.614: E/AndroidRuntime(1272): at com.descoper.rom.Galerie$1.onItemClick(Galerie.java:61)
04-29 15:38:59.614: E/AndroidRuntime(1272): at android.widget.AdapterView.performItemClick(AdapterView.java:299)
04-29 15:38:59.614: E/AndroidRuntime(1272): at android.widget.AbsListView.performItemClick(AbsListView.java:1113)
04-29 15:38:59.614: E/AndroidRuntime(1272): at android.widget.AbsListView$PerformClick.run(AbsListView.java:2904)
04-29 15:38:59.614: E/AndroidRuntime(1272): at android.widget.AbsListView$3.run(AbsListView.java:3638)
04-29 15:38:59.614: E/AndroidRuntime(1272): at android.os.Handler.handleCallback(Handler.java:733)
04-29 15:38:59.614: E/AndroidRuntime(1272): at android.os.Handler.dispatchMessage(Handler.java:95)
04-29 15:38:59.614: E/AndroidRuntime(1272): at android.os.Looper.loop(Looper.java:136)
04-29 15:38:59.614: E/AndroidRuntime(1272): at android.app.ActivityThread.main(ActivityThread.java:5017)
04-29 15:38:59.614: E/AndroidRuntime(1272): at java.lang.reflect.Method.invokeNative(Native Method)
04-29 15:38:59.614: E/AndroidRuntime(1272): at java.lang.reflect.Method.invoke(Method.java:515)
04-29 15:38:59.614: E/AndroidRuntime(1272): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-29 15:38:59.614: E/AndroidRuntime(1272): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-29 15:38:59.614: E/AndroidRuntime(1272): at dalvik.system.NativeStart.main(Native Method)
Galerie.java第61行：
dialog = new Dialog(getApplicationContext());
答案 0 :(得分：2)
您应该使用Activity上下文来显示对话框，而不是getApplicationContext。
更改
dialog = new Dialog(getApplicationContext());
到
dialog = new Dialog(Galerie.this);
当您使用上下文来修改UI时，您应该使用Activity上下文，因为对话框由Activity拥有。即Galerie.this
当您使用上下文执行非活动时，您应该使用应用程序上下文。
答案 1 :(得分：0)
尝试移动
dialog = new Dialog(getApplicationContext());
dialog.setContentView(R.layout.dialog1);
在onItemClick之外。
另外，使用 dialog = new Dialog(this); 代替dialog = new Dialog(getApplicationContext())。