Question

我在访问处理加载和保存的自定义类方法时遇到问题。虽然它们属于同一类，但这些方法仍然有效。但是因为我决定重复使用save / load方法，所以我需要在单独的类中使用它们，但是当我尝试访问这些方法程序崩溃时，任何人都有一个解释为什么？也许问题出在MODE_PRIVATE但我尝试更改它仍然会崩溃

package com.main.kanji_sama;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.CheckBox;

import com.main.customClass.sharedPreferences;

public class Hiragana extends Activity implements OnClickListener{

    CheckBox cb1,cb2;
    Button backButton;
    sharedPreferences myFunction = new sharedPreferences();


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_hiragana);


        cb1 = (CheckBox) findViewById(R.id.hiragana_xx_check);
        cb1.setChecked(myFunction.loadSharedPref("cb1"));
        cb2 = (CheckBox) findViewById(R.id.hiragana_kx_check);
        cb2.setChecked(myFunction.loadSharedPref("cb2"));

        backButton = (Button) findViewById(R.id.hiraganaconfbutton);
        backButton.setOnClickListener(this);
    }
    @Override
    public void onClick(View v){
        startActivity(new Intent(Hiragana.this, Main.class));   
    }
    public void onCheckboxClicked(View view) {
    boolean checked = ((CheckBox) view).isChecked();
    switch(view.getId()) {
        case R.id.hiragana_xx_check:
            myFunction.saveSharedPref("cb1",checked);
        break;  
        case R.id.hiragana_kx_check:
            myFunction.saveSharedPref("cb2", checked);

    }
}
}
**This is my class**

public class sharedPreferences extends Activity {

    public boolean loadSharedPref(String key){
        SharedPreferences preferences = getApplicationContext().getSharedPreferences("Kanji-Sama", android.content.Context.MODE_PRIVATE);
        return preferences.getBoolean(key, false);
        }
    public void saveSharedPref(String key,boolean value){
        SharedPreferences preferences = getApplicationContext().getSharedPreferences("Kanji-Sama", android.content.Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = preferences.edit();
        editor.putBoolean(key, value);
        editor.commit();
        }
}

Answer 1

您无需再使用其他课程，也无需延长Activity。请更改您的代码。

public class Hiragana extends Activity implements OnClickListener {

CheckBox cb1, cb2;
Button backButton;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_hiragana);

    cb1 = (CheckBox) findViewById(R.id.hiragana_xx_check);
    cb1.setChecked(myFunction.loadSharedPref("cb1"));
    cb2 = (CheckBox) findViewById(R.id.hiragana_kx_check);
    cb2.setChecked(myFunction.loadSharedPref("cb2"));

    backButton = (Button) findViewById(R.id.hiraganaconfbutton);
    backButton.setOnClickListener(this);
}

@Override
public void onClick(View v) {
    startActivity(new Intent(Hiragana.this, Main.class));
}

public void onCheckboxClicked(View view) {
    boolean checked = ((CheckBox) view).isChecked();
    switch (view.getId()) {
    case R.id.hiragana_xx_check:
        saveSharedPref("cb1", checked);
        break;
    case R.id.hiragana_kx_check:
        saveSharedPref("cb2", checked);

    }
}

public boolean loadSharedPref(String key) {
    SharedPreferences preferences = getApplicationContext()
            .getSharedPreferences("Kanji-Sama",
                    android.content.Context.MODE_PRIVATE);
    return preferences.getBoolean(key, false);
}

public void saveSharedPref(String key, boolean value) {
    SharedPreferences preferences = getApplicationContext()
            .getSharedPreferences("Kanji-Sama",
                    android.content.Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = preferences.edit();
    editor.putBoolean(key, value);
    editor.commit();
}
}

你也需要为onCheckedChange编写CheckBox监听器。

Answer 2

您的课程已扩展活动。

public class sharedPreferences extends Activity

尝试删除extends activity并添加类成员Context，Constructor传递Context（getApplicationContext（）。
并且你在方法中改变你的类使用类成员。

自定义类方法访问

2 个答案: