java如果铃声音量达到最大值,如何打开开关?如果铃声音量小于最大值,如何关闭开关?
//将音量开关设置为ON
swVolume.setChecked(true);
//附加侦听器以检查状态的更改
swVolume.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
}
});
//在显示屏幕之前检查当前状态
if(swVolume.isChecked()){
AudioManager am = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
am.setStreamVolume(
AudioManager.STREAM_RING,
am.getStreamMaxVolume(AudioManager.STREAM_RING),
0);
}
else {
swVolume.setChecked(false);
}
有人能告诉我为什么不能将if-else代码添加到侦听器中吗? 侦听器功能只是为了查看开关状态吗
我在网上看到了一个例子:
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) {
但是我真的不知道为什么我需要输入两次if-else语句,因为即使我在这里删除if-else语句,代码仍然可以正常工作。 谁能给我解释一下吗
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;
}
}
非常感谢。:)
共 (0) 个答案