如何在Android应用程序中保存复选框状态 [英] How to save a checkbox state in android app
问题描述
我有一个带有简单复选框的应用程序,当用户按下该应用程序时,会在build.prop上添加一行,这是可行的,但是当我退出该应用程序时,该复选框已重置,有没有办法通过添加一个来防止这种情况您的帖子中的示例代码,因为我仍然是Android应用程序的新手.
I have this app with a simple checkbox which adds a line to build.prop when the user presses it , the thing works but when i exit the app the check box is reseted , is there a way to prevent this with adding a sample code in your post because i am still newbie to android apps.
MainActivity.java
MainActivity.java
package com.mythi.tests;
import java.io.DataOutputStream;
import java.io.IOException;
import android.app.Activity;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void onCheckboxClicked(View view) {
// Is the view now checked?
boolean checked = ((CheckBox) view).isChecked();
// Check which checkbox was clicked
switch(view.getId()) {
case R.id.checkBox1:
if (checked){
try{
Process su = Runtime.getRuntime().exec("su");
DataOutputStream outputStream = new DataOutputStream(su.getOutputStream());
outputStream.writeBytes("cp /system/build.prop /system/build.prop.bak\n");
outputStream.writeBytes("echo 'persist.sys.scrollingcache=3' >> /system/build.prop\n");
outputStream.flush();
outputStream.writeBytes("exit\n");
outputStream.flush();
su.waitFor();
}catch(IOException e){
}catch(InterruptedException e){
}
}else{
try{
Process su = Runtime.getRuntime().exec("su");
DataOutputStream outputStream = new DataOutputStream(su.getOutputStream());
outputStream.writeBytes("rm -r /system/build.prop\n");
outputStream.writeBytes("mv /system/build.prop.bak /system/build.prop\n");
outputStream.flush();
outputStream.writeBytes("exit\n");
outputStream.flush();
su.waitFor();
}catch(IOException e){
}catch(InterruptedException e){
}
break;
}
}
}
}
activity_main.xml
activity_main.xml
<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"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.mythi.tests.MainActivity" >
<CheckBox
android:id="@+id/checkBox1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="169dp"
android:onClick="onCheckboxClicked"
android:text="CheckBox" />
</RelativeLayout>
推荐答案
使用getRuntime().exec()在哪里得到了这种极为奇怪的方法?这是一个使用SharedPreferences的简单工作代码示例.用以下内容替换您的整个交换语句:
Where did you get this extremely odd approach using getRuntime().exec()? Here's an easy working code sample for you using SharedPreferences. Replace your whole switch-statement with this one:
switch(view.getId()) {
case R.id.checkBox1:
PreferenceManager.getDefaultSharedPreferences(this).edit()
.putBoolean("checkBox1", checked).commit();
break;
}
在onCreate()内部添加以下内容:
Inside onCreate() add this:
CheckBox checkBox1 = (CheckBox) findViewById(R.id.checkBox1);
boolean checked = PreferenceManager.getDefaultSharedPreferences(this)
.getBoolean("checkBox1", false);
checkBox1.setChecked(checked);
完成.
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