每次單擊按鈕來回切換活動時，我都試圖將變量計數的值增加一。但是，每次我單擊時，計數值仍然相同。有人可以幫忙嗎？我正在嘗試放置一些生命周期 android 代碼，但它仍然沒有任何區別。package com.darayuth.learning;import android.content.Context;import android.content.Intent;import android.support.annotation.Nullable;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.Log;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;import com.squareup.picasso.Picasso;public class MainActivity extends AppCompatActivity { public static final String EXTRA_MESSAGE = "com.darayuth.learning"; public static final String TAG = "MainActivity"; public static final String value = "value"; private int count = 0; private TextView textView; @Override protected void onSaveInstanceState(Bundle outState) { outState.putInt(value, count); super.onSaveInstanceState(outState); } @Override protected void onRestoreInstanceState(Bundle savedInstanceState) { super.onRestoreInstanceState(savedInstanceState); count = savedInstanceState.getInt(value); } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); textView = findViewById(R.id.textView2); Button btn = findViewById(R.id.button); btn.setOnClickListener((View v)->{ sendMessage(); }); } public void sendMessage(){ count = count + 1; Log.i(TAG, "value: " + count); Intent intent = new Intent(this, Main2Activity.class); EditText editText = findViewById(R.id.editText); String message = editText.getText().toString(); intent.putExtra(EXTRA_MESSAGE, message ); startActivity(intent); }}</LinearLayout>
1 回答
慕容森
TA貢獻1853條經驗 獲得超18個贊
我建議使用 SharedPreferences 來存儲和檢索活動之間的值。
private void storeValue(){
? ? SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
? ? // Store an integer using the Shared Preferences editor
? ? SharedPreferences.Editor editor = prefs.edit();
? ? editor.putInt("myPreferenceValueKey", value); // Store the value with a key to identify it
? ? editor.apply();
}
private void retrieveValue(){
? ? SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
? ? int defaultValue = 0; // This is the value that's returned if the preference doesn't exist
? ? // Retrieve the stored value using the associated key
? ? value = prefs.getInt("myPreferenceValueKey", defaultValue);
}
在您的第一個活動中，只需在增加值之后但在開始下一個活動之前調用retrieveValue()您的onCreate()then 調用。storeValue()
您可以在第二個 Activity 中創建相同的函數來根據需要存儲和檢索值。
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