Java 从第二个活动传输数据时出错
我有两项活动。Java 从第二个活动传输数据时出错,java,android,Java,Android,我有两项活动。 FirstActivity带有一个文本视图和一个按钮，以及 main活动带有4个复选框、1个文本视图和1个按钮。 第一个活动是应用程序向用户显示的第一个活动。 在第一个活动中，我想检查textView中检查了多少复选框。 在MainActivity all working fine上，我们可以选择复选框，然后textView显示选中了多少。另外，复选框的状态和textView的状态会保存到SharedReference中 现在我描述我的问题，我不知道如何在我的应用程序启动后的第
FirstActivitymain活动我试图在ActivityResult上使用
，但我认为我这样做是错误的，我的双重意图的按钮2也一定是错误的
我应该在这里修复什么，如何修复
我将我的两项活动的代码粘贴到此处：
FirstActivity:
public class FirstActivity extends AppCompatActivity {
private static final String SHARED_PREFS_NAME = "abc";
private Button b1;
private TextView tv2;
private int number;
public static final int REQUEST_CODE = 100;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_first);
b1 = (Button)findViewById(R.id.b1);
tv2 = (TextView)findViewById(R.id.tv2) ;
b1.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent intent = new Intent(FirstActivity.this, MainActivity.class);
startActivityForResult(intent, REQUEST_CODE);
}
});
SharedPreferences preferences = getSharedPreferences(SHARED_PREFS_NAME, MODE_PRIVATE);
number = preferences.getInt("NUMBER", 0);
tv2.setText(""+number);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_OK) {
if (requestCode == REQUEST_CODE) {
int number = data.getExtras().getInt("number");
tv2.setText(""+number);
number = getIntent().getExtras().getInt("number");
saveNumberToSharedPrefs(number);
}
}
}
private void saveNumberToSharedPrefs(int num){
SharedPreferences preferences = getSharedPreferences(SHARED_PREFS_NAME, MODE_PRIVATE); //Create and store this instance in onCreate method of activity, or use it like this.
preferences.edit().putInt("NUMBER", num).apply(); // Use constant value for key
}
public class MainActivity extends AppCompatActivity implements CompoundButton.OnCheckedChangeListener {
private int numberOfTrue;
private TextView tv1;
private CheckBox cb1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
CheckBox cb2,cb3,cb4;
Button b2;
b2 = (Button)findViewById(R.id.b2);
tv1 = (TextView)findViewById(R.id.tv1);
cb1 = (CheckBox)findViewById(R.id.cb1);
cb1.setChecked(getFromSP("cb1"));
cb1.setOnCheckedChangeListener(this);
cb2 = (CheckBox)findViewById(R.id.cb2);
cb2.setChecked(getFromSP("cb2"));
cb2.setOnCheckedChangeListener(this);
cb3 = (CheckBox)findViewById(R.id.cb3);
cb3.setChecked(getFromSP("cb3"));
cb3.setOnCheckedChangeListener(this);
cb4 = (CheckBox)findViewById(R.id.cb4);
cb4.setChecked(getFromSP("cb4"));
cb4.setOnCheckedChangeListener(this);
loadVariable();
b2.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent output = new Intent();
output.putExtra("number", numberOfTrue);
setResult(Activity.RESULT_OK, output);
finish();
}
});
}
private boolean getFromSP(String key){
SharedPreferences preferences = getApplicationContext().getSharedPreferences("PROJECT_NAME", android.content.Context.MODE_PRIVATE);
return preferences.getBoolean(key, false);
}
private void saveInSp(String key,boolean value) {
SharedPreferences preferences = getApplicationContext().getSharedPreferences("PROJECT_NAME", android.content.Context.MODE_PRIVATE);
SharedPreferences.Editor editor = preferences.edit();
editor.putBoolean(key, value);
editor.commit();
}
private void saveVariable(int numberOfTrue){
SharedPreferences sharedPref = this.getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putInt("key2", numberOfTrue);
editor.commit();
}
private void loadVariable(){
SharedPreferences sharedPref = this.getPreferences(Context.MODE_PRIVATE);
int number = sharedPref.getInt("key2", 0);
tv1.setText(""+number);
numberOfTrue=number;
}
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
switch(buttonView.getId()){
case R.id.cb1:
saveInSp("cb1",isChecked);
if (isChecked == true){
numberOfTrue++;
}
else
{
numberOfTrue--;
}
break;
case R.id.cb2:
saveInSp("cb2",isChecked);
if (isChecked == true){
numberOfTrue++;
}
else
{
numberOfTrue--;
}
break;
case R.id.cb3:
saveInSp("cb3",isChecked);
if (isChecked == true){
numberOfTrue++;
}
else
{
numberOfTrue--;
}
break;
case R.id.cb4:
saveInSp("cb4",isChecked);
if (isChecked == true){
numberOfTrue++;
}
else
{
numberOfTrue--;
}
break;
}
saveVariable(numberOfTrue);
loadVariable();
}
}
main活动：
public class FirstActivity extends AppCompatActivity {
private static final String SHARED_PREFS_NAME = "abc";
private Button b1;
private TextView tv2;
private int number;
public static final int REQUEST_CODE = 100;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_first);
b1 = (Button)findViewById(R.id.b1);
tv2 = (TextView)findViewById(R.id.tv2) ;
b1.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent intent = new Intent(FirstActivity.this, MainActivity.class);
startActivityForResult(intent, REQUEST_CODE);
}
});
SharedPreferences preferences = getSharedPreferences(SHARED_PREFS_NAME, MODE_PRIVATE);
number = preferences.getInt("NUMBER", 0);
tv2.setText(""+number);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_OK) {
if (requestCode == REQUEST_CODE) {
int number = data.getExtras().getInt("number");
tv2.setText(""+number);
number = getIntent().getExtras().getInt("number");
saveNumberToSharedPrefs(number);
}
}
}
private void saveNumberToSharedPrefs(int num){
SharedPreferences preferences = getSharedPreferences(SHARED_PREFS_NAME, MODE_PRIVATE); //Create and store this instance in onCreate method of activity, or use it like this.
preferences.edit().putInt("NUMBER", num).apply(); // Use constant value for key
}
public class MainActivity extends AppCompatActivity implements CompoundButton.OnCheckedChangeListener {
private int numberOfTrue;
private TextView tv1;
private CheckBox cb1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
CheckBox cb2,cb3,cb4;
Button b2;
b2 = (Button)findViewById(R.id.b2);
tv1 = (TextView)findViewById(R.id.tv1);
cb1 = (CheckBox)findViewById(R.id.cb1);
cb1.setChecked(getFromSP("cb1"));
cb1.setOnCheckedChangeListener(this);
cb2 = (CheckBox)findViewById(R.id.cb2);
cb2.setChecked(getFromSP("cb2"));
cb2.setOnCheckedChangeListener(this);
cb3 = (CheckBox)findViewById(R.id.cb3);
cb3.setChecked(getFromSP("cb3"));
cb3.setOnCheckedChangeListener(this);
cb4 = (CheckBox)findViewById(R.id.cb4);
cb4.setChecked(getFromSP("cb4"));
cb4.setOnCheckedChangeListener(this);
loadVariable();
b2.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent output = new Intent();
output.putExtra("number", numberOfTrue);
setResult(Activity.RESULT_OK, output);
finish();
}
});
}
private boolean getFromSP(String key){
SharedPreferences preferences = getApplicationContext().getSharedPreferences("PROJECT_NAME", android.content.Context.MODE_PRIVATE);
return preferences.getBoolean(key, false);
}
private void saveInSp(String key,boolean value) {
SharedPreferences preferences = getApplicationContext().getSharedPreferences("PROJECT_NAME", android.content.Context.MODE_PRIVATE);
SharedPreferences.Editor editor = preferences.edit();
editor.putBoolean(key, value);
editor.commit();
}
private void saveVariable(int numberOfTrue){
SharedPreferences sharedPref = this.getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putInt("key2", numberOfTrue);
editor.commit();
}
private void loadVariable(){
SharedPreferences sharedPref = this.getPreferences(Context.MODE_PRIVATE);
int number = sharedPref.getInt("key2", 0);
tv1.setText(""+number);
numberOfTrue=number;
}
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
switch(buttonView.getId()){
case R.id.cb1:
saveInSp("cb1",isChecked);
if (isChecked == true){
numberOfTrue++;
}
else
{
numberOfTrue--;
}
break;
case R.id.cb2:
saveInSp("cb2",isChecked);
if (isChecked == true){
numberOfTrue++;
}
else
{
numberOfTrue--;
}
break;
case R.id.cb3:
saveInSp("cb3",isChecked);
if (isChecked == true){
numberOfTrue++;
}
else
{
numberOfTrue--;
}
break;
case R.id.cb4:
saveInSp("cb4",isChecked);
if (isChecked == true){
numberOfTrue++;
}
else
{
numberOfTrue--;
}
break;
}
saveVariable(numberOfTrue);
loadVariable();
}
}这一条肯定是错的
Intent intent = new Intent(MainActivity.this, FirstActivity.class);
intent.putExtra("number", numberOfTrue);
startActivityForResult(intent,1);
Intent output = new Intent();
output.putExtra("number", numberOfTrue);
setResult(Activity.RESULT_OK, output);
finish();
您只需要留下代码的第二部分。像这样：
Intent output = new Intent();
output.putExtra("number", numberOfTrue);
setResult(Activity.RESULT_OK, output);
finish();
然后像这样开始您的main活动
：
Intent intent = new Intent(FirstActivity.this, MainActivity.class);
startActivityForResult(intent, REQUEST_CODE); // This change is important.
然后这样做：
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == REQUEST_CODE && resultCode == Activity.RESULT_OK && data != null) {
number = getIntent().getExtras().getInt("number");
}
}
这样，当关闭时，您将从MainActivity
接收号码。但是，如果您想在FirstActivity
start（而不去MainActivity
）上读取此值，则需要将选中的数字存储在共享首选项中，然后在onCreate（）
方法的FirstActivity
中获取值。
将onActivityResult
中的SharedReferences
写入，以确保只保存“已保存”的支票
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == REQUEST_CODE && resultCode == Activity.RESULT_OK && data != null) {
number = getIntent().getExtras().getInt("number");
saveNumberToSharedPrefs(number);
}
}
private void saveNumberToSharedPrefs(int num){
SharedPreferences preferences = getSharedPreferences(SHARED_PREFS_NAME, MODE_PRIVATE); //Create and store this instance in onCreate method of activity, or use it like this.
preferences.edit().putInt("NUMBER", num).apply(); // Use constant value for key
}
然后您可以在onCreate
方法的FirstActivity
@Override
protected void onCreate(Bundle savedInstanceState) {
....
SharedPreferences preferences = getSharedPreferences(SHARED_PREFS_NAME, MODE_PRIVATE);
number = preferences.getInt("NUMBER", 0);
}
更新
在这里，您试图从onActivityResult
中的intent中获取数字。这是错误的，这样您将始终使用数字=0（默认值）。onactivity结果不会将数据填充到intent中。所有数据都在传入方法的data
变量中
number = getIntent().getExtras().getInt("number");
saveNumberToSharedPrefs(number);
您只需留下以下内容：
if (requestCode == REQUEST_CODE) { //also you need to check if result is RESULT_OK
number = data.getExtras().getInt("number");
tv2.setText(""+number);
saveNumberToSharedPrefs(number);
}
第一个活动
存储值：
Intent intent = new Intent(getBaseContext(), Activity.class);
intent.putExtra("ID", sessionId);
startActivity(intent);
第二项活动
获取值：
String s = getIntent().getStringExtra("ID");
更改FirstActivity.java
b1.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent intent = new Intent(FirstActivity.this, MainActivity.class);
startActivityForResult(intent, REQUEST_CODE);
}
});
b2.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Log.d("TAG","------"+numberOfTrue);
Intent output = new Intent();
output.putExtra("number", numberOfTrue);
setResult(Activity.RESULT_OK, output);
finish();
}
});
在ActivityResult上添加
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_OK) {
if (requestCode == REQUEST_CODE) {
Log.d("TAG","------"+data.getExtras().getInt("number"));
int number = data.getExtras().getInt("number");
tv2.setText(""+number);
}
}
}
更改MainActivity.java
b1.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent intent = new Intent(FirstActivity.this, MainActivity.class);
startActivityForResult(intent, REQUEST_CODE);
}
});
b2.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Log.d("TAG","------"+numberOfTrue);
Intent output = new Intent();
output.putExtra("number", numberOfTrue);
setResult(Activity.RESULT_OK, output);
finish();
}
});
@steve点击按钮B2输入Log并检查变量numberOfTrue的值，如Log.d（“TAG”、“----------”+numberOfTrue）；当我选中2个框时，日志显示：“TAG:------------2”所以我觉得这很好opinion@steve不，当点击按钮B2时，LogcatNow中显示的内容我不明白，点击按钮B2后，numberOfTrue有一个很好的值，那么现在有什么问题吗？是的，我现在在B2中有相同的内容，在Android监视器中我看到：“06-29 13:04:59.372 16785-16785/com.example.selection D/TAG:------3”-当我有3个复选框时，当我只有1个复选框时，我看到：“06-29 13:07:32.702 16785-16785/com.example.selection D/TAG:------1”最后我实现了这项第一部分工作，我的应用程序将良好的数据从MainActivity传输到FirstActivity，但我尝试“在FirstActivity开始时读取此值（不转到MainActivity）”没有工作，你能检查我的代码吗？我用当前的代码更新了我的问题