02-27 22:53:13.047: E/AndroidRuntime(11744): FATAL EXCEPTION: main
02-27 22:53:13.047: E/AndroidRuntime(11744): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.itcuties.android.reader/com.itcuties.android.reader.ItemDescriptionActivity}: java.lang.NullPointerException
02-27 22:53:13.047: E/AndroidRuntime(11744): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
02-27 22:53:13.047: E/AndroidRuntime(11744): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
02-27 22:53:13.047: E/AndroidRuntime(11744): at android.app.ActivityThread.access$600(ActivityThread.java:141)
02-27 22:53:13.047: E/AndroidRuntime(11744): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
02-27 22:53:13.047: E/AndroidRuntime(11744): at android.os.Handler.dispatchMessage(Handler.java:99)
02-27 22:53:13.047: E/AndroidRuntime(11744): at android.os.Looper.loop(Looper.java:137)
02-27 22:53:13.047: E/AndroidRuntime(11744): at android.app.ActivityThread.main(ActivityThread.java:5041)
02-27 22:53:13.047: E/AndroidRuntime(11744): at java.lang.reflect.Method.invokeNative(Native Method)
02-27 22:53:13.047: E/AndroidRuntime(11744): at java.lang.reflect.Method.invoke(Method.java:511)
02-27 22:53:13.047: E/AndroidRuntime(11744): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
02-27 22:53:13.047: E/AndroidRuntime(11744): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
02-27 22:53:13.047: E/AndroidRuntime(11744): at dalvik.system.NativeStart.main(Native Method)
02-27 22:53:13.047: E/AndroidRuntime(11744): Caused by: java.lang.NullPointerException
02-27 22:53:13.047: E/AndroidRuntime(11744): at com.itcuties.android.reader.ItemDescriptionActivity.onCreate(ItemDescriptionActivity.java:18)
02-27 22:53:13.047: E/AndroidRuntime(11744): at android.app.Activity.performCreate(Activity.java:5104)
02-27 22:53:13.047: E/AndroidRuntime(11744): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
02-27 22:53:13.047: E/AndroidRuntime(11744): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
02-27 22:53:13.047: E/AndroidRuntime(11744): ... 11 more
和ItemDescriptionActivity.java
package com.itcuties.android.reader;
import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
import com.itcuties.android.reader.R;
public class ItemDescriptionActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.item);
Bundle bundle = getIntent().getExtras();
String item_description = bundle.getString("description");
TextView desc = (TextView) findViewById(R.layout.item);
desc.setText(item_description);
}
}
应用正在获取 rss 数据,在 ListView 中显示标题。我试图在点击时添加显示说明,但应用程序在点击时崩溃。什么会导致这些错误?
最佳答案
您需要将 id
传递给 findViewById()
,也许您打算使用 findViewById(R.id.item);
。如果您仍然遇到相同的 LogCat 错误,请确保布局 item.xml
实际上有一个 id 为 @+id/item
的 TextView。
也不是每个 Activity 都是从一个 Intent 开始的,也不是每个 Intent 都有额外的,在使用它们之前你应该确保这些值都不是 null
。
添加另一个 RSS 值
让我们将链接与描述一起传递:
public void onItemClick(AdapterView<?> parent, View view, int pos, long id) {
Intent intent = new Intent(activity, ItemDescriptionActivity.class);
RSSItem item = listItems.get(pos);
intent.putExtra("description", item.getDescription());
intent.putExtra("link", item.getLink());
activity.startActivity(intent);
}
接下来我们将在 ItemDescriptionActivity
中创建一个新的类变量:
String item_link;
最后设置按钮以在网页中打开链接:
item_link = bundle.getString("link");
Button link = (Button) findViewById(R.id.button1);
link.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
Intent browse = new Intent(Intent.ACTION_VIEW, Uri.parse(item_link));
startActivity(browse);
}
}
关于android activitythread settext错误,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/15122746/