AndroidStudio学习笔记一：了解Activity

注意：特别提醒，官方帮助文档打开太慢，建议使用：http://www.android-doc.com/

一、Activity 的生命周期



二、Activity之间数据的传递

1、传递简单数据

A页面：

findViewById(R.id.newActivity).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent activity = new Intent(MainActivity.this, Main2Activity.class);
activity.putExtra("data", "Hello word");
startActivity(activity);
}
});

B页面：

private TextView textWord;

//接受传值Intent newActivity = getIntent();textWord = (TextView) findViewById(R.id.textView2);textWord.setText(newActivity.getStringExtra("data"));

2、数据传递 包Bundle

A页面：

Bundle b = new Bundle();
b.putString("name", "meimei");
b.putInt("age", 23);
//                activity.putExtras(b);
activity.putExtra("data", b);

B页面：

Intent newActivity = getIntent();

//        Bundle data = newActivity.getExtras();
Bundle data = newActivity.getBundleExtra("data");
textWord = (TextView) findViewById(R.id.textView2);
textWord.setText(data.getString("name"));

3、传递值对象

A、使用implements Serializable 传值(Java 语言自带的序列化) 操作简单，速度较慢

activity.putExtra("user", new User("xiaomi", 23));

User user = (User) newActivity.getSerializableExtra("user");
textWord.setText(user.getName());

B、使用Parcelable传值(操作复杂，Studio支持比较好，速度比较快)

model:

public class User implements Parcelable {

private String name;
private  int age;

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}

public  User(String name, int age){
this.name = name;
this.age = age;
}

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

@Override
public void writeToParcel(Parcel dest, int flags) {
//没有自带序列化方式，需要手动实现
dest.writeString(getName());
dest.writeInt(getAge());
}

public static final Creator<User> CREATOR = new Creator<User>() {
@Override
public User createFromParcel(Parcel source) {
return new User(source.readString(), source.readInt());
}

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

}

//接受值

User user = (User) newActivity.getParcelableExtra("user");
textWord.setText(user.getName());

4、获取Activity的返回参数

A、页面：

startActivityForResult(activity, 0);

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
backText = (TextView) findViewById(R.id.textView123);
backText.setText(data.getStringExtra("data"));
}

B、页面

findViewById(R.id.button).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent();
editText = (EditText) findViewById(R.id.editText2);
i.putExtra("data", editText.getText().toString());
setResult(1, i);
finish();
}
});

注意事项：在A页面实现onActivityResult 方法

三、Activity的启动模式

android:launchMode="singleTop"