Android保存ArrayList至SharedPreferences

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【Android保存ArrayList至SharedPreferences】保存ArrayList至SharedPreferences
其中ArrayList中每个元素为String

List< String> environmentList = new ArrayList< String> (); SharedPreferences.Editor editor = getSharedPreferences("EnvironDataList", MODE_PRIVATE).edit(); editor.putInt("EnvironNums", environmentList.size()); for (int i = 0; i < environmentList.size(); i++) { editor.putString("item_"+i, environmentList.get(i)); } editor.commit();

对应的取出操作为：

List< String> environmentList = new ArrayList< String> (); SharedPreferences preferDataList = getSharedPreferences("EnvironDataList", MODE_PRIVATE); int environNums = preferDataList.getInt("EnvironNums", 0); for (int i = 0; i < environNums; i++) { String environItem = preferDataList.getString("item_"+i, null); environmentList.add(environItem); }

保存ArrayList至SharedPreferences，其中list的每个元素为自定义对象
1 首先将自定义对象序列化

public class CoordinateAlterSample implements Serializable { private double x; private double y; private String name; public double getX() { return x; } public void setX(double x) { this.x = x; } public double getY() { return y; } public void setY(double y) { this.y = y; } public String getName() { return name; } public void setName(String name) { this.name = name; }}

其次，将list转为json，即可保存到SharedPreferences中

List< CoordinateAlterSample> alterSamples = new ArrayList< CoordinateAlterSample> (); SharedPreferences.Editor editor = getSharedPreferences("AlterSamplesList", MODE_PRIVATE).edit(); Gson gson = new Gson(); String json = gson.toJson(alterSamples); Log.d(TAG, "saved json is "+ json); editor.putString("alterSampleJson", json); editor.commit();

对应的取出操作为：

SharedPreferences preferences = getSharedPreferences("AlterSamplesList", MODE_PRIVATE); String json = preferences.getString("alterSampleJson", null); if (json != null) { Gson gson = new Gson(); Type type = new TypeToken< List< CoordinateAlterSample> > (){}.getType(); List< CoordinateAlterSample> alterSamples = new ArrayList< CoordinateAlterSample> (); alterSamples = gson.fromJson(json, type); for(int i = 0; i < alterSamples.size(); i++) { Log.d(TAG, alterSamples.get(i).getName()+":" + alterSamples.get(i).getX() + "," + alterSamples.get(i).getY()); } }