Question

我正在制作一个简单的android应用。我有3类MainActivity，PlayerDetailActivity和Player。没有为putExtra找到合适的方法，这是一个错误。然后，我在Player类中添加了工具Serializable。现在程序可以编译，但是却显示为空白。在我看来，我的意图有问题。你能帮忙吗。预先谢谢你。

MainActivity类

public class MainActivity extends AppCompatActivity implements AdapterView.OnItemClickListener {
List<Player> bostonCeltics = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    bostonCeltics.add(new Player("Kyrie Irving", "23-Mar-92", 190.5, "Point guard", R.mipmap.irving));
    bostonCeltics.add(new Player("Jayson Tatum", "3-Mar-98", 190.5, "Small forward", R.mipmap.tatum));
    bostonCeltics.add(new Player("Gordon Hayward", "23-Mar-90", 203.2, "Small forward", R.mipmap.hayward));
    bostonCeltics.add(new Player("Robert Williams", "17-Oct-97", 208.3, "Power forward", R.mipmap.williams));
    bostonCeltics.add(new Player("Jabari Bird", "3-Jul-94", 198.1, "Shooting guard", R.mipmap.bird));
    bostonCeltics.add(new Player("Al Horford", "3-Jun-86", 208.3, "Center / Power forward", R.mipmap.horford));
    bostonCeltics.add(new Player("Jaylen Brown", "24-Oct-96", 200.7, "Small forward/ Shooting guard", R.mipmap.brown));
    bostonCeltics.add(new Player("Marcus Smart", "6-Mar-94", 193.0, "Shooting guard / Point guard", R.mipmap.smart));
    bostonCeltics.add(new Player("Terry Rozier", "17-Mar-94", 185.4, "Point guard", R.mipmap.rozier));
    bostonCeltics.add(new Player("Aron Baynes", "9-Dec-86", 208.3, "Center / Power forward", R.mipmap.baynes));
    bostonCeltics.add(new Player("Marcus Morris", "2-Sep-89", 205.7, "Forward", R.mipmap.morris));
    bostonCeltics.add(new Player("Brad Wanamaker", "25-Jul-89", 193.0, "Point guard / Shooting guard", R.mipmap.wanamaker));
    bostonCeltics.add(new Player("P. J. Dozier", "25-Oct-96", 198.1, "Shooting guard", R.mipmap.dozier));
    bostonCeltics.add(new Player("Daniel Theis", "4-Apr-92", 203.2, "Center / Power forward", R.mipmap.theis));
    bostonCeltics.add(new Player("Guerschon Yabusele", "17-Dec-95", 203.2, "Power forward", R.mipmap.yabusele));
    bostonCeltics.add(new Player("Semi Ojeleye", "5-Dec-94", 200.7, "Forward", R.mipmap.ojeleye));
    bostonCeltics.add(new Player("Walt Lemon Jr.", "26-Jul-92", 190.5, "Point guard", R.mipmap.lemon));
}
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
    Intent moveToDetailIntent = new Intent(getBaseContext(), PlayerDetailActivity.class);
    moveToDetailIntent.putExtra("player", bostonCeltics.get(position));
    startActivity(moveToDetailIntent);
}

玩家类

enter codepublic class Player implements Serializable {
private String name;
private String age;
private double height;
private String position;
private int image;
Player(String name, String age, double height, String position, int image) {
    this.name = name;
    this.age = age;
    this.height = height;
    this.position = position;
    this.image = image;
}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public String getAge() {
    return age;
}
public void setAge(String age) {
    this.age = age;
}
public double getHeight() {
    return height;
}
public void setHeight(double height) {
    this.height = height;
}
public String getPosition() {
    return position;
}
public void setPosition(String position) {
    this.position = position;
}
public int getImage() {
    return image;
}
public void setImage(int image) {
    this.image = image;
}}

PlayerDetailActivity类

public class PlayerDetailActivity extends AppCompatActivity {

TextView nameTextView;
TextView ageTextView;
TextView heightTextView;
TextView positionTextView;
ImageView imageView;

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

    nameTextView = (TextView) findViewById(R.id.nameTextView);
    ageTextView = (TextView) findViewById(R.id.ageTextView);
    heightTextView = (TextView) findViewById(R.id.heightTextView);
    positionTextView = (TextView) findViewById(R.id.positionTextView);
    imageView = (ImageView) findViewById(R.id.imageView);

    Player player = (Player) getIntent().getExtras().get("player");

    nameTextView.setText(player.getName());
    ageTextView.setText("Birth date: " + player.getAge());
    heightTextView.setText("Height: " + player.getHeight());
    positionTextView.setText("Position: " + player.getPosition());
    imageView.setImageResource(player.getImage());
}}

清单

<?xml version="1.0" encoding="utf-8"?>

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".PlayerDetailActivity" />
    <activity android:name=".Main2Activity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".IntroActivity"></activity>
</application>

Answer 1

我建议您使用Parcelable而不是Serializable，因为Parcelable的过程要快得多。

Player.java

import android.os.Parcel;
import android.os.Parcelable;

public class Player implements Parcelable {

    private String name;
    private String age;
    private double height;
    private String position;
    private int image;

    Player(String name, String age, double height, String position, int image) {
        this.name = name;
        this.age = age;
        this.height = height;
        this.position = position;
        this.image = image;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getAge() {
        return age;
    }
    public void setAge(String age) {
        this.age = age;
    }
    public double getHeight() {
        return height;
    }
    public void setHeight(double height) {
        this.height = height;
    }
    public String getPosition() {
        return position;
    }
    public void setPosition(String position) {
        this.position = position;
    }
    public int getImage() {
        return image;
    }
    public void setImage(int image) {
        this.image = image;
    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeString(this.name);
        dest.writeString(this.age);
        dest.writeDouble(this.height);
        dest.writeString(this.position);
        dest.writeInt(this.image);
    }

    protected Player(Parcel in) {
        this.name = in.readString();
        this.age = in.readString();
        this.height = in.readDouble();
        this.position = in.readString();
        this.image = in.readInt();
    }

    public static final Parcelable.Creator<Player> CREATOR = new Parcelable.Creator<Player>() {
        @Override
        public Player createFromParcel(Parcel source) {
            return new Player(source);
        }

        @Override
        public Player[] newArray(int size) {
            return new Player[size];
        }
    };
}

现在您可以使用Intent将此对象发送到其他活动：

Intent intent = new Intent(context, PlayerDetailActivity.class);
intent.putExtra("player", bostonCeltics.get(position));
startActivity(intent);

在PlayerDetailActivity类中，使用它来提取数据：

PlayerDetailActivity player = getIntent().getExtras().getParcelable("player");

找不到适合putExtra的方法

1 个答案: