[英]Android Studio Sending Variables To Other Activities and Opening Activities At The Same Time
[英]Android studio use same integer in 2 activities
我正在制作一个android应用程序,因此我需要在2个活动中使用一个整数值。 我尝试使用此代码,但是没有用。
//Integer Sender
Intent myIntent = new Intent(A.this, B.class);
myIntent.putExtra("MyIntNameGoesHere", intValue);
startActivity(myIntent);
//Integer receiver
Intent mIntent = getIntent();
int intValue = mIntent.getIntExtra("intVariableName", 0);
它说无法解析符号intValue和无法解析符号A,而对于B则相同。这是完整的代码。 主要活动:
import android.content.Intent;
import android.content.SharedPreferences;
import android.preference.PreferenceManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
int balance;
private SharedPreferences preferences;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Hide notification bar
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
//Click counter
final TextView text = (TextView) findViewById(R.id.balance_text);
assert text != null;
// to retreuve the values from the shared preference
preferences = PreferenceManager.getDefaultSharedPreferences(this);
balance = preferences.getInt("balance", 0);
text.setText(balance + " $");
final ImageButton button = (ImageButton) findViewById(R.id.click_button);
assert button != null;
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
balance++;
text.setText("" + balance + " $");
SharedPreferences.Editor editor = preferences.edit();
editor.putInt("balance", balance);
editor.apply();
}
});
final Button UpgradesButton = (Button) findViewById(R.id.upgrades_button);
assert UpgradesButton != null;
UpgradesButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(MainActivity.this, UpgradesActivity.class));
}
});
//Balance Integer Sender
}
}
升级活动:
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
public class UpgradesActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_upgrades);
//Hide notification bar
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
final Button e2u_button = (Button) findViewById(R.id.e2u_button);
assert e2u_button != null;
e2u_button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
}
});
final Button back_button = (Button) findViewById(R.id.back_button);
assert back_button != null;
back_button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(UpgradesActivity.this, MainActivity.class));
}
});
//TODO: Pass balance integer from MainActivity to here.
}
}
错误代码:
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.WindowManager;
import android.widget.Button;
public class UpgradesActivity extends AppCompatActivity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_upgrades);
//Receive balance from MainActivity
Intent mIntent = getIntent();
int intValue = mIntent.getIntExtra("key_int", 0);
//Hide notification bar
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
final Button e2u_button = (Button) findViewById(R.id.e2u_button);
assert e2u_button != null;
e2u_button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if(balance >= 300){ //ERROR ON THIS LINE
}
}
});
final Button back_button = (Button) findViewById(R.id.back_button);
assert back_button != null;
back_button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(UpgradesActivity.this, MainActivity.class));
}
});
//TODO: Pass balance integer from MainActivity to here.
}
}
上面所有内容都已答复! -------------------------------------------------- -------
现在我对这部分代码有疑问:
@Override
public void onClick(View v) {
if(balance >= 300){
balance -= 300;
}
if(balance < 300){
final TextView text = (TextView) findViewById(R.id.not_enough_money_text);
assert text != null;
text.setText("You do not have enough money.");
Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
text.setText("");
}
}, 2000);
}
}
当我单击按钮时,它说我没有足够的钱,但是我有300多个。请帮助我。 我发现了问题所在,但不确定如何解决。 我需要将余额发送回MainActivity。 有人可以帮忙吗?
在发送和接收Int时,您正在使用其他密钥。 更改此行:
int intValue = mIntent.getIntExtra("intVariableName", 0);
对此:
int intValue = mIntent.getIntExtra("MyIntNameGoesHere", 0);
发送这样的数据-
UpgradesButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(MainActivity.this, UpgradesActivity.class);
intent.putExtra("key_int", balance);
startActivity(intent);
}
});
并在UpgradesActivity
onCreate()
中获取它-
Intent mIntent = getIntent();
int intValue = mIntent.getIntExtra("key_int", 0);
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