我的问题是如果有可能在主Activity
的onCreate()
方法setContentView()
之前编写代码。在下面的代码中,我想在setContentView()
之前调用setVariables()
,但这会导致我的应用程序崩溃。如果我在setContentView()
之后拨打setVariables()
,它可以正常工作。为什么是这样?setContentView故障之前的代码
package com.oxinos.android.moc;
import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.content.res.Resources;
import android.os.Bundle;
import android.view.View;
import android.widget.CheckBox;
public class mocActivity extends Activity {
/** Called when the activity is first created. */
public static String prefsFile = "mocPrefs";
SharedPreferences mocPrefs;
public Resources res;
public CheckBox cafesCB, barsRestCB, clothingCB, groceriesCB, miscCB;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setVariables();
setContentView(R.layout.main);
mocPrefs = getSharedPreferences(prefsFile,0);
}
private void setVariables(){
res = getResources();
cafesCB = (CheckBox) findViewById(R.id.cafesCheckBox);
barsRestCB = (CheckBox) findViewById(R.id.barsRestCheckBox);
clothingCB = (CheckBox) findViewById(R.id.clothingCheckBox);
groceriesCB = (CheckBox) findViewById(R.id.groceriesCheckBox);
miscCB = (CheckBox) findViewById(R.id.miscCheckBox);
}
public void submitHandler(View view){
switch (view.getId()) {
case R.id.submitButton:
boolean cafes = cafesCB.isChecked();
boolean barsRest = barsRestCB.isChecked();
boolean clothing = clothingCB.isChecked();
boolean groceries = groceriesCB.isChecked();
boolean misc = miscCB.isChecked();
SharedPreferences.Editor editor = mocPrefs.edit();
editor.putBoolean(res.getString(R.string.cafesBool), cafes);
editor.putBoolean(res.getString(R.string.barsRestBool), barsRest);
editor.putBoolean(res.getString(R.string.clothingBool), clothing);
editor.putBoolean(res.getString(R.string.groceriesBool), groceries);
editor.putBoolean(res.getString(R.string.miscBool), misc);
editor.commit();
startActivity(new Intent(this, mocActivity2.class));
break;
}
}
}
尽管这个问题已经得到了充分的回答,只是为了解释'setContentView(...)'执行了一种叫'布局通货膨胀'的事情。这意味着它会解析相关文件中的XML(在您的案例中为main.xml),并创建其中所有UI元素的实例。然后它将该观点附加到该活动。当你调用'findViewById(...)'时,它不会直接引用main.xml,而是引用附加到Activity的内容视图,换句话说就是'setContentView(...)'夸大的内容视图。 – Squonk 2012-04-14 12:13:46