Java 开始新活动的自定义列表?
我构建了一个定制的列表项,通过膨胀每个列表项来替换android的简单列表项。自定义列表正在工作,它由Java 开始新活动的自定义列表?,java,android,eclipse,listview,android-activity,Java,Android,Eclipse,Listview,Android Activity,我构建了一个定制的列表项,通过膨胀每个列表项来替换android的简单列表项。自定义列表正在工作,它由图像视图和文本视图组成 我的问题是,当我尝试在单击列表项后启动一个新的活动时,什么都没有发生,即使应用程序不会崩溃。那么,有没有一种方法可以使用列表视图启动活动 public class activityone extends ListActivity { @Override public void onCreate(Bundle savedInstanceState) {
图像视图
和文本视图
组成
我的问题是,当我尝试在单击列表项后启动一个新的活动时,什么都没有发生,即使应用程序不会崩溃。那么,有没有一种方法可以使用列表视图启动活动
public class activityone extends ListActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activitylayout);
setListAdapter(new MyAdapter(this, android.R.layout.simple_list_item_1, R.id.textView1,
getResources().getStringArray(R.array.names)));
}
public void onListItemClick(ListView l, View v, int position,
long id) {
// TODO Auto-generated method stub
super.onListItemClick(l, v, position, id);
Object o = this.getListAdapter().getItem(position);
if(getSelectedItemPosition() == 0){
Intent intent = new Intent(activityone.this,no1.class);
startActivity(intent);
}
.
.
.
.
}
private class MyAdapter extends ArrayAdapter<String>{
public MyAdapter(Context context, int resource, int textViewResourceId,
String[] strings) {
super(context, textViewResourceId, strings);
// TODO Auto-generated constructor stub
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View row = inflater.inflate(R.layout.list_item, parent, false);
String[] items = getResources().getStringArray(R.array.names);
ImageView iv = (ImageView) row.findViewById(R.id.imageView1);
TextView tv = (TextView) row.findViewById(R.id.textView1);
tv.setText(items[position]);
if(items[position].equals("john")){
iv.setImageResource(R.drawable.john);
}
.
.
.
.
return row;
}
}
}
是的,我的活动
被添加到清单xml文件
谢谢你的帮助
@Vineet Shukla我不知道怎么做我设置了一个断点但我无法调试我是eclipse环境的新手你能解释一下吗
@迪维耶什
我编辑了代码,现在当我按下一个列表项时应用程序崩溃了这里是Logcat跟踪
09-17 10:10:57.686: ERROR/AndroidRuntime(365): FATAL EXCEPTION: main
09-17 10:10:57.686: ERROR/AndroidRuntime(365): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.abc.act/com.abc.act.no1}: java.lang.NullPointerException
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.os.Handler.dispatchMessage(Handler.java:99)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.os.Looper.loop(Looper.java:123)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.app.ActivityThread.main(ActivityThread.java:4627)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at java.lang.reflect.Method.invokeNative(Native Method)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at java.lang.reflect.Method.invoke(Method.java:521)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at dalvik.system.NativeStart.main(Native Method)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): Caused by: java.lang.NullPointerException
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at com.abc.act.no1.onCreate(no1.java:31)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): ... 11 more
如果没有有效地使用此API,则应切换到SimpleAdapter,因为它可以处理更复杂的列表项布局和数据绑定。您需要有效地使用列表的底层数据,而不是创建难以处理的分支语句。调试并检查是否正在接收调用:if(getSelectEditePosition()==0){Intent Intent=new Intent(activityone.this,no1.class);startActivity(Intent);}你为什么不使用?@Dan S你能解释一下吗?我看不出有什么不同!有人是空的,请正确检查您的代码,空指针异常也给出了类的行号,其中为空值……。我不理解您所问的内容,但如果您询问的是no1类,则如上所示,我认为空指针异常位于iv.setImageResource(R.drawable.john);
09-17 10:10:57.686: ERROR/AndroidRuntime(365): FATAL EXCEPTION: main
09-17 10:10:57.686: ERROR/AndroidRuntime(365): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.abc.act/com.abc.act.no1}: java.lang.NullPointerException
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.os.Handler.dispatchMessage(Handler.java:99)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.os.Looper.loop(Looper.java:123)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.app.ActivityThread.main(ActivityThread.java:4627)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at java.lang.reflect.Method.invokeNative(Native Method)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at java.lang.reflect.Method.invoke(Method.java:521)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at dalvik.system.NativeStart.main(Native Method)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): Caused by: java.lang.NullPointerException
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at com.abc.act.no1.onCreate(no1.java:31)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
09-17 10:10:57.686: ERROR/AndroidRuntime(365): ... 11 more