我可以在oncreate方法之外使用setContentView吗？

Question

我见过很多人告诉你可以在oncreate方法之外设置setContentView,但我没有找到任何例子.现在,当我尝试使用setContentView时,我的应用程序崩溃了.这是我的源代码:

AlarmActivity.java:

package com.alarm.example;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.RelativeLayout;

public class AlarmActivity extends Activity{
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Button buton = new Button(this);
        buton.setId(101);
        buton.setText("New alarm");
        buton.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,LayoutParams.WRAP_CONTENT));
        RelativeLayout layout1 = new RelativeLayout(this);  
        layout1.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));  
    layout1.addView(buton);  
    setContentView(layout1); 

    Button nou =(Button)findViewById(101);
    nou.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v){
            New_ala nou1=new New_ala();
            nou1.nou_alarma();
            }
        });
    }
}

New_ala.java:

package com.alarm.example;

public class New_ala extends AlarmActivity{
public void nou_alarma() {
setContentView(R.layout.timepicker);        
}
}

TimePicker.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >


    <TimePicker
        android:id="@+id/timePicker"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />

    <LinearLayout 
        android:layout_height="wrap_content" 
        android:layout_width="fill_parent" 
        android:layout_alignParentBottom="true">

        <Button 
        android:id="@+id/picker_save" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:layout_weight="1" 
        android:text="Save">
        </Button>

        <Button 
        android:id="@+id/picker_cancel" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content"
        android:layout_weight="1" 
        android:text="Cancel">
        </Button>
</LinearLayout>

</LinearLayout>

更详细的说,我可以在oncreate方法中使用setContentView(R.layout.timepicker)而不会出现任何问题,因此问题是setContentView在New_ala.java类中无法正常工作.谁能帮我？

设置意图后的代码:AlarmActivity:

package com.alarm.example;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
public class AlarmActivity extends Activity{
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        startActivity(new Intent(this, NewAlarmActivity.class));
        }
    }

NewAlarmActivity:

package com.alarm.example;
import android.os.Bundle;
public class NewAlarmActivity extends AlarmActivity{

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.timepicker);
}
    }

Answer 1

您可以在事件(UI)线程上运行时调用setContentView.请注意,执行此操作时,findViewById需要重置通过调用初始化的任何字段.

Answer 2

最好的方法是拥有多个活动：而不是nou1.nou_alarma();创建一个意图并使用新布局启动一个新活动。

startActivity(new Intent(this, NewAlarmActivity.class));

并在onCreate的方法中NewAlarmActivity，将内容视图设置为R.layout.timepicker