我在android本地数据库中存储intent.putExtra时遇到问题。我为我的项目创建了一个类似4Pics1Word的游戏。它只有25个级别，因此我创建了25个活动，我将其随机化。解决特定活动后，它将被移除到类的ArrayList ArrayList<Class>。现在，我使用intent.putExtra("ACTIVITY_LIST", activityList);来存储意图并将其传递给下一个活动。我的问题是我无法将其存储在本地数据库中。当我退出游戏时，进度不会保存，它会从第一级开始。有什么建议？谢谢！
这是我在主要活动中的代码：
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
Button btnStart;
Context context;
SharedPreferences mPrefs = getPreferences(MODE_PRIVATE);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btnStart = (Button) findViewById(R.id.btnStart);
btnStart.setOnClickListener(this);
}
@Override
public void onClick(View v) {
// We are creating a list, which will store the activities that haven't been opened yet
ArrayList<Class> activityList = new ArrayList<>();
activityList.add(first.class);
activityList.add(second.class);
activityList.add(third.class);
activityList.add(fourth.class);
activityList.add(fifth.class);
Random generator = new Random();
int number = generator.nextInt(5) + 1;
Class activity = null;
switch(number) {
case 1:
activity = first.class;
activityList.remove(first.class);
break;
case 2:
activity = second.class;
activityList.remove(second.class);
break;
case 3:
activity = third.class;
activityList.remove(third.class);
break;
case 4:
activity = fourth.class;
activityList.remove(fourth.class);
break;
default:
activity = fifth.class;
activityList.remove(fifth.class);
break;
}
Intent intent = new Intent(getBaseContext(), activity);
intent.putExtra("ACTIVITY_LIST", activityList);
SharedPreferences.Editor prefsEditor = mPrefs.edit();
Gson gson = new Gson();
String json = gson.toJson(activityList); // myObject - instance of MyObject
prefsEditor.putString("MyObject", json);
prefsEditor.commit();
startActivity(intent);
}
}
以下是我第一次活动中的代码：
public class first extends AppCompatActivity implements View.OnClickListener{
EditText etAnswer;
Button btnGo;
Context context;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_first);
etAnswer = (EditText) findViewById(R.id.etAnswer);
btnGo = (Button) findViewById(R.id.btnGo);
btnGo.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch(v.getId()){
case R.id.btnGo:
String answer = etAnswer.getText().toString();
if(answer.equals("Jose Rizal") || answer.equals("jose rizal") || answer.equals("Rizal") || answer.equals("rizal") ){
AlertDialog.Builder dlgAlert = new AlertDialog.Builder(this);
dlgAlert.setMessage("The famous Rizal monument in Luneta was not the work of a Filipino but a Swiss sculptor named Richard Kissling?" +
"\n" +
"\n" +
"Source: http://www.joserizal.ph/ta01.html");
dlgAlert.setTitle("Did you know that ...");
dlgAlert.setPositiveButton("Next",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
ArrayList<Class> activityList = new ArrayList<>();
Bundle extras = getIntent().getExtras();
activityList = (ArrayList<Class>) extras.get("ACTIVITY_LIST");
if(activityList.size() == 0) {
Context context = getApplicationContext();
CharSequence last = "Congratulations! You just finished the game! Please wait for the next update!";
int durationFinal = Toast.LENGTH_LONG;
Toast toast = Toast.makeText(context, last, durationFinal);
toast.show();
} else {
// Now, the random number is generated between 1 and however many
// activities we have remaining
Random generator = new Random();
int number = generator.nextInt(activityList.size()) + 1;
Class activity = null;
// Here, we are checking to see what the output of the random was
switch(number) {
case 1:
// We will open the first remaining activity of the list
activity = activityList.get(0);
// We will now remove that activity from the list
activityList.remove(0);
break;
case 2:
// We will open the second remaining activity of the list
activity = activityList.get(1);
activityList.remove(1);
break;
case 3:
// We will open the third remaining activity of the list
activity = activityList.get(2);
activityList.remove(2);
break;
case 4:
// We will open the fourth remaining activity of the list
activity = activityList.get(3);
activityList.remove(3);
break;
default:
// We will open the fifth remaining activity of the list
activity = activityList.get(4);
activityList.remove(4);
break;
}
// Note: in the above, we might not have 3 remaining activities, for example,
// but it doesn't matter because that case wouldn't be called anyway,
// as we have already decided that the number would be between 1 and the number of
// activities left.
// Starting the activity, and passing on the remaining number of activities
// to the next one that is opened
Intent intent = new Intent(getBaseContext(), activity);
intent.putExtra("ACTIVITY_LIST", activityList);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
startActivity(intent);
}
}
});
dlgAlert.setCancelable(true);
dlgAlert.create().show();
}else{
Context context = getApplicationContext();
CharSequence text = "Wrong! Try Again.";
int duration = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context, text, duration);
toast.show();
}
break;
}
}
}
答案 0 :(得分：1)
MainActivity时，您都会新建一个ArrayList并添加所有活动，而不是从本地SharedPreferences获取缓存。 更新arrayList后，像这样保存arrayList：
SharedPreferences.Editor prefsEditor = mPrefs.edit();
Gson gson = new Gson();
String json = gson.toJson(activityList); // myObject - instance of MyObject
prefsEditor.putString("MyObject", json);
prefsEditor.commit();
当你想要读取保存的arrayList时，请执行以下操作：
String arrayStr = mPrefs.getString("myObject","defValue");
Gson gson = new Gson();
List<Class> array = gson.fromGson(arrayStr,new TypeToken<List<Class>>(){}.getType());
if(array==null){
array = new ArrayList<>();
array.add(...);
}