Java 我如何从一个活动中访问一个方法并将其用于Android中的另一个活动?
我有一个名为的班级,我有Java 我如何从一个活动中访问一个方法并将其用于Android中的另一个活动?,java,android,android-activity,Java,Android,Android Activity,我有一个名为的班级,我有 public class iHave extends ActionBarActivity { //below is the instance for calling the method from the other activity. (The name of the other activity is **iThank**) **iThank thankYou = new iThank();** @Override protected void onC
public class iHave extends ActionBarActivity
{
//below is the instance for calling the method from the other activity.
(The name of the other activity is **iThank**)
**iThank thankYou = new iThank();**
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_i_have);
Button button = (Button) findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener()
{
@Override
public void onClick(View v)
{
**//this is the method I want to access from iThank class** **strong text**
thankYou.display();
}
});
}
//下一节课是“iThank”
我如何将iTank活动的“public void display()
”方法用于“iHave”活动?它总是给我一个NullPointerException
错误。请帮忙。多谢各位
如何从一个活动访问一个方法并将其用于另一个活动
Android中的活动
通过创建对象让其他人从活动中访问方法是正确的方法
用于在应用程序组件之间进行通信
1.从i发送广播在按钮上单击:
@Override
public void onClick(View v)
{
Intent intent = new Intent("DISPLAY_EVENT");
LocalBroadcastManager.getInstance(v.getContext()).sendBroadcast(intent);
}
2.在iTank
活动中注册LocalBroadcastManager
:
@Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
LocalBroadcastManager.getInstance(this).registerReceiver(ReceiveMessage,
new IntentFilter("DISPLAY_EVENT"));
}
private BroadcastReceiver ReceiveMessage = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
// TODO Auto-generated method stub
display();
}
};
3.在iThank
活动中创建BroadcastReceiver
对象和调用display()方法:
@Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
LocalBroadcastManager.getInstance(this).registerReceiver(ReceiveMessage,
new IntentFilter("DISPLAY_EVENT"));
}
private BroadcastReceiver ReceiveMessage = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
// TODO Auto-generated method stub
display();
}
};
还为TextView添加空签入显示方法:
public void display()
{
if(txtThank !=null)
txtThank.setText ("Shine");
}
请不要这样做,这不是活动的目的。您可能需要先看一看,然后开始。如果您想从当前前台活动(例如,iHave
)启动新活动(例如,iTank
),则从不直接自己实例化类,并且始终。如果您有数据要传递(例如要显示的消息),则需要将其作为额外的目的捆绑在一起(请参见相同的链接)
活动不应该直接调用彼此的方法,因为这需要它们相互引用。该框架独立地管理每个活动的生命周期,这些引用可能导致泄漏