Android 始终将开关值设置为null

目前，我的一个XML文件中有两个开关。以下是该文件的代码，以防万一：

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

<Switch
    android:id="@+id/switch1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Countdown Sound Effects"
    android:checked="true" />

<Switch
    android:id="@+id/switch2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Ding Sound Effect when Correct"
    android:checked = "true" />


</LinearLayout>

有什么我真的错过的小东西吗？我似乎不明白。谢谢

试试这段代码

XML

---

试试这种方法，希望这能帮助你解决问题。

选项activity.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical">
   <Switch
       android:id="@+id/switch1"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:checked="true"/>

    <Switch
        android:id="@+id/switch2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:checked="true"/>

    <TextView
        android:id="@+id/textSwitch1Value"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"/>

    <TextView
        android:id="@+id/textSwitch2Value"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"/>

</LinearLayout>

---

为什么不使用切换按钮？同时检查：我已经试过了，你的代码运行得很好，你能告诉我这两种方法在哪里吗？

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:padding="5dp">

    <Switch
        android:id="@+id/mySwitch"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="20dp"
        android:text="Play with the Switch" />

    <TextView
        android:id="@+id/switchStatus"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_below="@+id/mySwitch"
        android:layout_marginTop="22dp"
        android:text="Medium Text"
        android:textAppearance="?android:attr/textAppearanceMedium" />

</RelativeLayout>

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.Switch;
import android.widget.TextView;

public class MainActivity extends Activity {

 private TextView switchStatus;
 private Switch mySwitch;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);

  switchStatus = (TextView) findViewById(R.id.switchStatus);
  mySwitch = (Switch) findViewById(R.id.mySwitch);

  //set the switch to ON 
  mySwitch.setChecked(true);
  //attach a listener to check for changes in state
  mySwitch.setOnCheckedChangeListener(new OnCheckedChangeListener() {

   @Override
   public void onCheckedChanged(CompoundButton buttonView,
     boolean isChecked) {

    if(isChecked){
     switchStatus.setText("Switch is currently ON");
    }else{
     switchStatus.setText("Switch is currently OFF");
    }

   }
  });

  //check the current state before we display the screen
  if(mySwitch.isChecked()){
   switchStatus.setText("Switch is currently ON");
  }
  else {
   switchStatus.setText("Switch is currently OFF");
  }
 }

 @Override
 public boolean onCreateOptionsMenu(Menu menu) {
  // Inflate the menu; this adds items to the action bar if it is present.
  getMenuInflater().inflate(R.menu.activity_main, menu);
  return true;
 }

}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical">
   <Switch
       android:id="@+id/switch1"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:checked="true"/>

    <Switch
        android:id="@+id/switch2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:checked="true"/>

    <TextView
        android:id="@+id/textSwitch1Value"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"/>

    <TextView
        android:id="@+id/textSwitch2Value"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"/>

</LinearLayout>

public class Settings extends Activity {

    private Switch switch1;
    private Switch switch2;
    private TextView textSwitch1Value;
    private TextView textSwitch2Value;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.optionsactivity);

        switch1 = (Switch) findViewById(R.id.switch1);
        switch2 = (Switch) findViewById(R.id.switch2);
        textSwitch1Value = (TextView) findViewById(R.id.textSwitch1Value);
        textSwitch2Value = (TextView) findViewById(R.id.textSwitch2Value);
        textSwitch1Value.setText("Switch : "+isSwitch1());
        textSwitch2Value.setText("Switch : "+isSwitch2());
    }

    private boolean isSwitch1(){
        return switch1.isChecked();
    }

    private boolean isSwitch2(){
        return switch2.isChecked();
    } 
}