[英]App crash when i tried to go to the second activity with a image button
[英]App Crash when I Add a Button - has both the Button AND a listview in Activity
我的應用程序有一個活動,其相應的Java代碼擴展了活動。 XML內部有一個按鈕和一個列表視圖。 可以單擊每個按鈕以轉到另一個活動(我尚未完成該部分)。
我的代碼有99%可以正常工作,除了當我“ findViewById”我的按鈕時,應用程序完全崩潰。 如果我刪除此行,則該應用程序可以正常工作(除了我的按鈕將無用的事實外)。
我的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" >
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:orientation="horizontal">
<ImageButton
android:id="@+id/bAddLexicon"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/new_pic"
android:contentDescription="New Lexicon"/>
</LinearLayout>
<ListView
android:id="@android:id/list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="15dp"></ListView>
</LinearLayout>
我的Java代碼:
package com.example.lexicav1;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.app.ListActivity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
public class ListLexica extends Activity {
ListView listview;
Button createLexicon;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.listlexica);
listview = (ListView) findViewById(android.R.id.list);
//THE FOLLOWING LINE MAKES MY APP CRASH,
//IF I ERASED THIS ONE LINE IT WOULD WORK BUT THEN
//I WOULD NOT BE ABLE TO DO ANYTHING WITH THE BUTTON???
createLexicon = (Button) findViewById(R.id.bAddLexicon);
List<String> items = new ArrayList<String>();
items.add("Lexicon 1");
items.add("Lexicon 2");
items.add("Lexicon 3");
ArrayAdapter<String> adapter =
new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, items);
listview.setAdapter(adapter);
listview.setOnItemClickListener(new OnItemClickListener()
{
@Override
public void onItemClick(AdapterView<?> arg0, View arg1,int position, long arg3)
{
//to change later
Intent intent = new Intent("android.intent.action.booklistactivity");
startActivity(intent);
}
});
}
}
將類型轉換按鈕鍵入ImageButton
當前您正在投射到Button
你有一個ImageButton
而不是一個Button
因此,也將其聲明為ImageButton
:
package com.example.lexicav1;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.app.ListActivity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
public class ListLexica extends Activity {
ListView listview;
ImageButton createLexicon;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.listlexica);
listview = (ListView) findViewById(android.R.id.list);
//THE FOLLOWING LINE MAKES MY APP CRASH,
//IF I ERASED THIS ONE LINE IT WOULD WORK BUT THEN
//I WOULD NOT BE ABLE TO DO ANYTHING WITH THE BUTTON???
createLexicon = (ImageButton) findViewById(R.id.bAddLexicon);
List<String> items = new ArrayList<String>();
items.add("Lexicon 1");
items.add("Lexicon 2");
items.add("Lexicon 3");
ArrayAdapter<String> adapter =
new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, items);
listview.setAdapter(adapter);
listview.setOnItemClickListener(new OnItemClickListener()
{
@Override
public void onItemClick(AdapterView<?> arg0, View arg1,int position, long arg3)
{
//to change later
Intent intent = new Intent("android.intent.action.booklistactivity");
startActivity(intent);
}
});
}
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.