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[英]Moving Data from ArrayList in Second activity to main activity - android
[英]Making userInput from main activity to display on second activity in Android
我在這里看到了一些相關的主題,但是經過多次嘗試,我似乎無法找到解決方案,因此希望有人可以提供幫助。 到目前為止,這是我的代碼(試圖使userInput作為結果出現在第二個活動中) :
MainActivity.java
package winfield.joe.wind.v1;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.View;
import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.Toast;
public class MainActivity extends Activity {
// public var
private EditText text;
// default func
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Toast.makeText(this, "onCreate!", Toast.LENGTH_LONG).show();
setContentView(R.layout.activity_main);
// findViewById = Finds a view that was identified by the id attribute
// from the XML that was processed in onCreate(Bundle).
// (EditText) = typecast
text = (EditText) findViewById(R.id.userInput);
}
//Will be executed by clicking on the calculate button because we assigned "calc" to the "onClick" Property
public void calc(View view) {
RadioButton toKilometers = (RadioButton) findViewById(R.id.toKilometers);
RadioButton toKnots = (RadioButton) findViewById(R.id.toKnots);
if (text.getText().length() == 0) {
// if the text field is empty show the message "enter a valid number" via toast message
Toast.makeText(this, "enter a valid number", Toast.LENGTH_LONG).show();
} else {
int userInput = R.string.userInput;
Intent i = new Intent(MainActivity.this, SecondActivity.class);
i.putExtra("userInput", userInput);
startActivityForResult(i, 0);
startActivity(i);
// parse input Value from Text Field
double inputValue = Double.parseDouble(text.getText().toString());
// convert to...
if (toKilometers.isChecked()) {
text.setText(String.valueOf(convertToKM(inputValue)));
// uncheck "to km" Button
toKilometers.setChecked(false);
// check "to knots" Button
toKnots.setChecked(true);
} else { /* if toKnots button isChecked() */
text.setText(String.valueOf(convertToKnots(inputValue)));
// uncheck "to knots" Button
toKnots.setChecked(false);
// check "to km" Button
toKilometers.setChecked(true);
}
}
}
/*private void putExtra(String string, int result) {
// TODO Auto-generated method stub
}*/
private double convertToKM(double inputValue) {
// convert knots to km
return (inputValue * 1.8);
}
private double convertToKnots(double inputValue) {
// convert km to knots
return (inputValue * 0.539956803);
}
}
SecondActivity.java
package winfield.joe.wind.v1;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;
public class SecondActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_second);
Toast.makeText(this, "onCreate!", Toast.LENGTH_LONG).show();
setContentView(R.layout.activity_main);
Intent i = getIntent();
String userInput = i.getStringExtra("userInput");
}
//onClick GoBack method assigned to the Go Back? button which returns the user to main activity from the second activity
public void GoBack(View view) {
//AlertDialog appears upon the onclick of the go back button
AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setTitle("Are you sure?");
// set dialog message
builder .setCancelable(false)
.setPositiveButton("Convert Again",new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,int id) {
//You return to Main Activity
Intent intent = new Intent(SecondActivity.this, MainActivity.class);
startActivity(intent);
}
})
.setNeutralButton("Back to Home",new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,int id) {
//You return to the home page
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_HOME);
startActivity(intent);
}
})
.setNegativeButton("View Results",new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog,int id) {
// if this button is clicked, just close the dialog box and do nothing
dialog.cancel();
}
});
AlertDialog alert = builder.create();
alert.show();
}
}
activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/LinearLayout1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_alignParentBottom="true"
android:layout_alignParentEnd="true"
android:background="@color/bgColor"
android:orientation="vertical">
<!--TITLE-->
<TextView
android:id="@+id/titleMain"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="22dp"
android:gravity="center"
android:text="@string/titleMain"
android:textColor="@color/textColor"
android:textColorHint="@color/textColor"
android:textColorLink="#ffffff"
android:textSize="30sp" />
<!--USER-INPUT-->
<EditText
android:id="@+id/userInput"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="20dp"
android:layout_marginRight="20dp"
android:ems="10"
android:hint="@+string/userInput"
android:inputType="numberDecimal"
android:paddingEnd="40dp"
android:paddingStart="20dp"
android:paddingTop="30dp" >
<requestFocus />
</EditText>
<!--TWO RADIO BUTTONS-->
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingLeft="10dp"
android:paddingRight="10dp">
<!--toKNOTS-->
<RadioButton
android:id="@+id/toKnots"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginStart="10dp"
android:layout_marginTop="10dp"
android:layout_weight="0.04"
android:checked="true"
android:text="@string/toKnots" />
<!--toKM-->
<RadioButton
android:id="@+id/toKilometers"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginEnd="20dp"
android:layout_marginTop="10dp"
android:text="@string/toKilometers" />
</LinearLayout>
<!--CALCULATE-->
<Button
android:id="@+id/calc"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginEnd="10dp"
android:layout_marginStart="10dp"
android:layout_marginTop="30dp"
android:onClick="calc"
android:text="@string/calc" />
</LinearLayout>
activity_second.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/LinearLayout1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_alignParentBottom="true"
android:layout_alignParentEnd="true"
android:background="@color/bgColor"
android:orientation="vertical"
tools:context="${relativePackage}.${activityClass}" >
<!-- TITLE -->
<TextView
android:id="@+id/titleResults"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="24dp"
android:gravity="center"
android:text="@string/titleResults"
android:textColor="@color/textColor"
android:textColorHint="@color/textColor"
android:textColorLink="#ffffff"
android:textSize="25sp" />
<TextView
android:id="@+id/result"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_margin="20dp"
android:layout_marginTop="30dp"
android:ems="10"
android:hint="@string/result"
android:textColorHint="@color/textColor" >
<requestFocus />
</TextView>
<Button
android:id="@+id/GoBack"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_marginTop="40dp"
android:text="@string/GoBack"
android:onClick="GoBack" />
</LinearLayout>
改變這個...
int userInput = R.string.userInput;
...至...
String userInput = text.getText().toString();
R.java
文件中的所有內容都是一個static final int
,用於引用資源-它實際上不是資源本身(例如,對於EditText
,不是資源的內容)。
我在您的代碼中看到兩個問題。
首先,將userInput設置為R.string.userInput,這是一種奇怪的imo。 您應該將userInput設置為TextField中的文本:
String userInput = text.getText().toString();
我注意到的第二個問題是您兩次啟動了第二個意圖。 一次是為了結果,一次是沒有結果:
startActivityForResult(i, 0);
startActivity();
如果您不想使用上一個活動的結果,請嘗試刪除startActivityForResult。 您可能誤會了startActivityForResult(i,0)所做的事情。
如果您想從活動中獲取結果,則基本上可以調用startActivityForResult()。 例如,您在MainActivity中,想要在其中顯示照片。 現在,您可以使用startActivityForResult()啟動相機意圖,並在拍照后可以在MainActivity中進行處理。
如果僅要將值傳遞給下一個活動,則只需一個簡單的startActivity()就足夠了。 如果您想了解更多有關此主題的信息,請點擊以下鏈接到文檔:
**This is the correct way to change information between 2 activity, of corse be careful to activity lifecycle. This code best practice!**
第一次活動
public class MainActivity extends Activity {
private static final String Tag = "ACTIVITY";
private static final String CONTATORE = "contatore";
TextView et;
Button btn,btnLancia;
int counter = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
et = (TextView) findViewById(R.id.et);
btn = (Button) findViewById(R.id.btn);
btnLancia = (Button) findViewById(R.id.btnLancia);
if(savedInstanceState != null){
counter = savedInstanceState.getInt(CONTATORE);
}
btnLancia.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
lanciaActivity();
}
});
et.setText("" + counter);
btn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
++counter;
et.setText("" + counter);
}
});
Log.d(Tag, "OnCreate");
}
protected void lanciaActivity() {
Intent intent = new Intent(this,Activity2.class);
Bundle bundle = new Bundle();
bundle.putInt(Activity2.VALUE, counter);
intent.putExtras(bundle);
startActivity(intent);
}
@Override
protected void onDestroy() {
super.onDestroy();
Log.d(Tag, "OnDestroy");
}
@Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
Log.d(Tag, "OnPause");
}
@Override
protected void onRestart() {
// TODO Auto-generated method stub
super.onRestart();
Log.d(Tag, "OnRestart");
}
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onRestoreInstanceState(savedInstanceState);
Log.d(Tag, "onRestoreInstanceState");
}
@Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
Log.d(Tag, "OnResume");
}
@Override
protected void onSaveInstanceState(Bundle outState) {
// TODO Auto-generated method stub
super.onSaveInstanceState(outState);
Log.d(Tag, "OnSaveIstantState");
outState.putInt(CONTATORE, counter);
}
@Override
protected void onStart() {
// TODO Auto-generated method stub
super.onStart();
Log.d(Tag, "OnStart");
}
@Override
protected void onStop() {
// TODO Auto-generated method stub
super.onStop();
Log.d(Tag, "OnStop");
}
}
第二活動
public class Activity2 extends Activity {
private static final String Tag = "ACTIVITY2";
public static final String VALUE = "value";
private static final String VALOREATT = "val";
TextView contatore;
Button button;
int contatoreq;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_activity2);
Log.d(Tag, "OnCreate");
contatore = (TextView) findViewById(R.id.textView1);
button = (Button) findViewById(R.id.btnDoppio);
if(savedInstanceState!=null){
contatoreq = savedInstanceState.getInt(VALOREATT);
}
else {
Intent intetn = getIntent();
Bundle bundle = intetn.getExtras();
if(bundle!=null)
contatoreq = bundle.getInt(VALUE);
}
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
contatoreq = contatoreq*2;
contatore.setText("" + contatoreq);
}
});
contatore.setText("" + contatoreq);
}
@Override
protected void onDestroy() {
super.onDestroy();
Log.d(Tag, "OnDestroy");
}
@Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
Log.d(Tag, "OnPause");
}
@Override
protected void onRestart() {
// TODO Auto-generated method stub
super.onRestart();
Log.d(Tag, "OnRestart");
}
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onRestoreInstanceState(savedInstanceState);
Log.d(Tag, "onRestoreInstanceState");
}
@Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
Log.d(Tag, "OnResume");
}
@Override
protected void onSaveInstanceState(Bundle outState) {
// TODO Auto-generated method stub
super.onSaveInstanceState(outState);
Log.d(Tag, "OnSaveIstantState");
outState.putInt(VALOREATT, contatoreq);
}
@Override
protected void onStart() {
// TODO Auto-generated method stub
super.onStart();
Log.d(Tag, "OnStart");
}
@Override
protected void onStop() {
// TODO Auto-generated method stub
super.onStop();
Log.d(Tag, "OnStop");
}
}
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