Question

我正在编写一个小应用程序。仅供参考：如果单击图像，计数器将减少。我的两个问题如下：

我如何通过一些代码来管理它，当我离开应用程序时，我的计数器会回到起点。例如。如果我在第5点离开并稍后回来，我想继续在第5点而不是10点。
我希望当计数器达到0时会出现一张全新的图片，但我不知道如何管理它。

要点2：我尝试过以下几行，但它不起作用。我离开时应用程序崩溃，例如在第6点。

@Override 
    protected void onPause() { 
        SharedPreferences mPrefs = getSharedPreferences("data", 0); 
        counter = mPrefs.getInt("counter", 0);
        SharedPreferences.Editor 
        mEditor = mPrefs.edit(); 
        mEditor.putInt("counter", counter).commit(); 
        onWindowFocusChanged(true);
        }

这是整个代码。我希望有人能够帮助我。：）

    package com.first.app;

import android.app.Activity;
import android.app.Fragment;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

    public class MainActivity extends Activity {

    int counter = 10;
    public static String TAG = "Debug";
    @Override 
    protected void onPause() { 
        SharedPreferences mPrefs = getSharedPreferences("data", 0); 
        SharedPreferences.Editor 
        mEditor = mPrefs.edit(); 
        mEditor.putInt("counter", counter).commit(); 
        onWindowFocusChanged(true);
        super.onPause(); 
        }

    @Override
    protected void onStop() {
        Log.w(TAG, "App stopped");
        //also do your savings here to be sure
        super.onStop();
    }

    @Override
    protected void onDestroy() {
        Log.w(TAG, "App destoryed");
        //also do your savings here to be sure
        super.onDestroy();
    }

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

        final TextView text = (TextView) findViewById(R.id.TextView01);
        final ImageView apfel = (ImageView) findViewById(R.id.appel);
        final ImageView image = (ImageView) findViewById(R.id.smiley);

        apfel.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (counter > 0) {
                    counter--;
                    text.setText("" + counter);
                }
                if (counter == 0) {
                    image.setImageResource(R.drawable.smiley);
                    text.setText("You finished!");
                }
            }
        });

        if (savedInstanceState == null) {
            getFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment()).commit();
        }
    }

    @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);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {

        public PlaceholderFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container,
                    false);
            return rootView;
        }
    }

}

自动安装以下代码行后的内容＆＃39;当我创建项目时。

if (counter == 0) {
                    text.setText("Congratulations you finished!");

Answer 1

如果应用程序打开，您可以将其写入文件并再次阅读。但我认为最好的方法是使用SharedPreferences。

您可以在此处找到示例：example

我尝试过以下几行，但它不起作用。该应用程序我离开时崩溃，例如在第6点。

您可以生成错误日志并发布吗？

Edit2：您需要在方法中使用onStop和onDestroy。喜欢这个

public static string TAG = "Debug";
@Override
protected void onStop() {
    Log.w(TAG, "App stopped");
    //also do your savings here to be sure
    super.onStop();
}

@Override
protected void onDestroy() {
    Log.w(TAG, "App destoryed");
    //also do your savings here to be sure
    super.onDestroy();
}

您的代码将是：

    package com.first.app;

import android.app.Activity;
import android.app.Fragment;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends Activity {

    int counter;
    public static string TAG = "Debug";
    @Override 
    protected void onPause() { 
        SharedPreferences mPrefs = getSharedPreferences("data", 0); 
        SharedPreferences.Editor 
        mEditor = mPrefs.edit(); 
        mEditor.putInt("counter", counter).commit(); 
        onWindowFocusChanged(true);
        super.onPause(); 
        }

    @Override
    protected void onStop() {
        Log.w(TAG, "App stopped");
        SharedPreferences mPrefs = getSharedPreferences("data", 0); 
        SharedPreferences.Editor 
        mEditor = mPrefs.edit(); 
        mEditor.putInt("counter", counter).commit(); 
        onWindowFocusChanged(true);
        super.onStop();
    }

    @Override
    protected void onDestroy() {
        Log.w(TAG, "App destoryed");
        SharedPreferences mPrefs = getSharedPreferences("data", 0); 
        SharedPreferences.Editor 
        mEditor = mPrefs.edit(); 
        mEditor.putInt("counter", counter).commit(); 
        onWindowFocusChanged(true);
        super.onDestroy();
    }

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

    SharedPreferences settings = getSharedPreferences("data", 0);
    counter = settings.getInt("counter", 10);

        final TextView text = (TextView) findViewById(R.id.TextView01);
        final ImageView apfel = (ImageView) findViewById(R.id.appel);
        final ImageView image = (ImageView) findViewById(R.id.smiley);

        apfel.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (counter > 0) {
                    counter--;
                    text.setText("" + counter);
                }
                if (counter == 0) {
                    image.setImageResource(R.drawable.smiley);
                    text.setText("You finished!");
                    SharedPreferences mPrefs = getSharedPreferences("data", 0); 
                    SharedPreferences.Editor 
                    mEditor = mPrefs.edit(); 
                    mEditor.putInt("counter", 10).commit(); 
                }
            }
        });

        if (savedInstanceState == null) {
            getFragmentManager().beginTransaction()
                    .add(R.id.container, new PlaceholderFragment()).commit();
        }
    }

    @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);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {

        public PlaceholderFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container,
                    false);
            return rootView;
        }
    }

}

退出应用程序并更改Android应用程序中的图片后，保存当前状态

1 个答案: