Android-SharePreferences保存數據

使用SharePreferences 保存數據可以使得數據得到永久的保存
首先看這裏是沒有文件的(找包名就是你的項目名稱)

測試1
直接在MainActivity中使用SharePreferences

package com.example.savedataforever;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        SharedPreferences shared = getPreferences(Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = shared.edit();
        editor.putInt("NUMBER",111);
        editor.apply();
        int x = shared.getInt("NUMBER",0);
        String TAG = "myTag";
        Log.d(TAG,"創建的x值爲："+x);
    }
}

當創建完成之後

會看見多了一個shared_prefs文件夾，裏面就是自己設置的需要永久保存的數據
測試2
使用數據類來保存數據
創建了一個data類

package com.example.savedataforever;

import android.content.Context;
import android.content.SharedPreferences;

public class myData {
    public int number;
    private Context context;
    public myData(Context context){
        this.context = context;
    }
    public void save(){
        SharedPreferences share = context.getSharedPreferences("Mydata",Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = share.edit();
        editor.putInt("MYNUMBER",this.number);
        editor.commit();
    }
    public int get(){
        SharedPreferences share = context.getSharedPreferences("Mydata",Context.MODE_PRIVATE);
        return share.getInt("MYNUMBER",0);

    }
}

使用data類

package com.example.savedataforever;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        myData mydata = new myData(this);
        mydata.number = 1000;
        mydata.save();
        int x = mydata.get();
        String TAG = "myTag";
        Log.d(TAG,"創建的x值爲："+x);
    }
}

測試結果

測試成功