Question

因此，我制作了一个程序，该程序自动创建CardViewes来在其中存储生日的日期和名称，并通过以下指南将它们添加到我的主活动的相对布局中：https://android--code.blogspot.com/2015/12/android-how-to-create-cardview.html。我有很多错误，并且修复了所有错误，直到现在我没有错误消息可以使用。如标题所示，CardViews不会出现在我的主活动中。如果有人可以帮助我，我将非常高兴。顺便说一句，我是编码的新手，没有太多经验，所以这可能也是问题所在。

主要活动Java：

package com.myuserwithoutme.birthdayremember;

import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.AdView;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Color;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.CardView;
import android.util.TypedValue;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;
import com.myuserwithoutme.birthdayremember.CreateActivity.*;


public class MainActivity extends AppCompatActivity{
private Context mContext;
RelativeLayout mRelativeLayout;
Boolean pressed = false;
String mEditText1;
String mEditText2;

/
private static final String TOAST_TEXT = "Test ads are being shown. "
        + "To show live ads, replace the ad unit ID in res/values/strings.xml with your own ad unit ID.";




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

    mContext = getApplicationContext();
    mRelativeLayout = findViewById(R.id.RelativeLayout);


    AdView adView = findViewById(R.id.adView);
    AdRequest adRequest = new AdRequest.Builder()
            .setRequestAgent("android_studio:ad_template").build();
    adView.loadAd(adRequest);


    Toast.makeText(this, TOAST_TEXT, Toast.LENGTH_LONG).show();


    FloatingActionButton fab1 = findViewById(R.id.fab1);
    fab1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent createIntent = new Intent(MainActivity.this,CreateActivity.class);
            startActivity(createIntent);
        }
    });




    Intent newcard = getIntent();
    for (int x = 1; x <= 0; x++) {
        if (newcard != null) {
            pressed = newcard.getExtras().getBoolean("card");
        }
    }
    Intent strings = getIntent();
    for (int x = 1; x <= 0; x++) {
        if (strings != null) {
            mEditText1 = strings.getExtras().getString("Name");
            mEditText2 = strings.getExtras().getString("Date");
        }
    }


        if (pressed != false) {
            CardView card = new CardView(mContext);
            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(
                    LinearLayout.LayoutParams.WRAP_CONTENT,
                    LinearLayout.LayoutParams.WRAP_CONTENT
            );
            card.setLayoutParams(params);
            card.setRadius(9);
            card.setContentPadding(15, 15, 15, 15);

            card.setCardBackgroundColor(Color.parseColor("#d3e8e7"));
            card.setMaxCardElevation(15);
            card.setCardElevation(9);
            TextView text = new TextView(mContext);
            text.setLayoutParams(params);
            text.setText(mEditText1 + "\n" + mEditText2);
            text.setTextSize(TypedValue.COMPLEX_UNIT_DIP, 30);
            text.setTextColor(Color.parseColor("#308985"));

            card.addView(text);
            mRelativeLayout.addView(card);
        }




}


@Override
public boolean onCreateOptionsMenu(Menu menu) {

    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {

    int id = item.getItemId();

    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

}

Xml主要活动：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:ads="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/RelativeLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">

<!-- view for AdMob Banner Ad -->
<LinearLayout
    android:id="@+id/layout1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <TextView
        android:id="@+id/textView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Testing" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
</LinearLayout>

<com.google.android.gms.ads.AdView
    android:id="@+id/adView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true"
    ads:adSize="BANNER"
    ads:adUnitId="@string/banner_ad_unit_id" />

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab1"
    android:layout_width="56dp"
    android:layout_height="56dp"
    android:layout_alignParentBottom="true"
    android:layout_alignParentEnd="true"
    android:layout_marginBottom="62dp"
    android:layout_marginEnd="15dp"
    android:clickable="true"
    android:src="@drawable/ic_baseline_add_24px"
    ads:backgroundTint="@android:color/darker_gray"
    ads:rippleColor="@android:color/background_light" />

感谢您的帮助

编辑：

第二活动：

package com.myuserwithoutme.birthdayremember;

import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.EditText;
import android.widget.TextView;
import android.content.Context;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.CardView;
import android.util.TypedValue;
import android.view.View;
import android.view.Window;
import android.widget.Button;
import android.widget.RelativeLayout;
import android.widget.LinearLayout.LayoutParams;
import android.widget.TextView;
import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Toast;

public class CreateActivity extends AppCompatActivity {

private EditText mEditText1;
private EditText mEditText2;
private String name;
private String date;

public boolean newcard;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_create);



    mEditText1 = findViewById(R.id.editText1);
    mEditText2 = findViewById(R.id.editText2 );
    name = mEditText1.getText().toString();
    date = mEditText2.getText().toString();


    final Intent newcard = new Intent(CreateActivity.this, MainActivity.class);
    FloatingActionButton fab2 = findViewById(R.id.fab2);
    fab2.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Intent mainIntent = new Intent(CreateActivity.this,MainActivity.class);
            startActivity(mainIntent);


            newcard.putExtra("card", true);

            Intent strings = new Intent(CreateActivity.this, MainActivity.class);
            strings.putExtra("Name", name);
            strings.putExtra("Date", date);
            startActivity(strings);



        }
    });

}
}

第二个Xml：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:ads="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/rl2"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">

<!-- view for AdMob Banner Ad -->
<com.google.android.gms.ads.AdView
    android:id="@+id/adView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_alignParentBottom="true"
    ads:adSize="BANNER"
    ads:adUnitId="@string/banner_ad_unit_id" />

<android.support.design.widget.FloatingActionButton
    android:id="@+id/fab2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_alignParentEnd="true"
    android:layout_marginBottom="61dp"
    android:layout_marginEnd="17dp"
    android:clickable="true"
    android:src="@drawable/ic_baseline_save_24px"
    ads:backgroundTint="@android:color/darker_gray"
    ads:rippleColor="@android:color/background_light" />

<EditText
    android:id="@+id/editText1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentStart="true"
    android:layout_alignParentTop="true"
    android:layout_marginTop="60dp"
    android:ems="10"
    android:hint="Name"
    android:inputType="textPersonName" />

<EditText
    android:id="@+id/editText2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentStart="true"
    android:layout_alignParentTop="true"
    android:layout_marginTop="126dp"
    android:ems="10"
    android:hint="DD/MM/YYYY"
    android:inputType="date" />

<TextView
    android:id="@+id/textView3"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentStart="true"
    android:layout_alignParentTop="true"
    android:layout_marginStart="18dp"
    android:layout_marginTop="24dp"
    android:text="Gib die Daten der Person ein" />

Answer 1

您必须以startActivityForResult而不是startActivity来开始活动，并且该活动会将结果值返回给MainActivity而不是其他：
https://developer.android.com/training/basics/intents/result

这些循环在做什么：

Intent newcard = getIntent();
for (int x = 1; x <= 0; x++) {
    if (newcard != null) {
        pressed = newcard.getExtras().getBoolean("card");
    }
}
Intent strings = getIntent();
for (int x = 1; x <= 0; x++) {
    if (strings != null) {
        mEditText1 = strings.getExtras().getString("Name");
        mEditText2 = strings.getExtras().getString("Date");
    }
}

由于起始值为x = 1，因此不会执行，因此永远不会为x <= 0。
也许尝试不使用循环：

Intent newcard = getIntent();
if (newcard != null) {
    pressed = newcard.getExtras().getBoolean("card");
}

Intent strings = getIntent();
if (strings != null) {
    mEditText1 = strings.getExtras().getString("Name");
    mEditText2 = strings.getExtras().getString("Date");
}

Answer 2

因此，我将尽力提供帮助。正如评论中提到的那样，可能您的代码未到达创建卡的那部分，这意味着按下的代码永远都不正确。

由于我没有您其他活动的代码，我想您可以通过删除似乎不循环的循环来摆脱问题

第一个活动

Intent intent = getIntent();
    if (intent != null) {
        pressed = intent.getExtras().getBoolean("card");
        mEditText1 = intent.getExtras().getString("Name");
        mEditText2 = intent.getExtras().getString("Date");
    }

getIntent将从您来自的活动中返回意图。您无需像创建两个意图那样创建它们，因为它们是相同的。

编辑

第二活动

您的代码永远不会达到“投入量”，因为您之前已经导航到另一个活动。你应该那样做。

    FloatingActionButton fab2 = findViewById(R.id.fab2);
    fab2.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            Intent intent = new Intent(CreateActivity.this, MainActivity.class);
            intent.putExtra("card", true);
            intent.putExtra("Name", name);
            intent.putExtra("Date", date);
            startActivity(intent);

        }
    });

还有一些代码提示。

代替

if (pressed != false)
// This means pressed is true.

使用

if (pressed)
// This also means pressed is true.

Answer 3

对于具有相同问题的人来说，只是快速编辑，startActivityForResult起初没有起作用，因为我有一个过时的版本，我将jdk和android studio更新到了最新版本，并且它起作用了。谢谢大家：D

以编程方式创建的CardView不会出现

3 个答案: