Android之Activity
1.跳转到另一个Activity
1.在activity_main中创建一个btn,并且改其id为pushBtton
2.新建一个Activity
3.在MainActivity中添加如下代码：
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
//添加的代码
findViewById(R.id.pushbutton).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(MainActivity.this,AnotherAtr.class));
}
});
}
2.Activity之生命周期
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
System.out.println("onCreat");
}
@Override
protected void onStart() {
super.onStart();
System.out.println("onStart");
}
@Override
protected void onResume() {
super.onResume();
System.out.println("onResume");
}
@Override
protected void onPause() {
super.onPause();
System.out.println("onPause");
}
@Override
protected void onStop() {
super.onStop();
System.out.println("onStop");
}
@Override
protected void onDestroy() {
super.onDestroy();
System.out.println("onDestory");
}
@Override
protected void onRestart() {
super.onRestart();
System.out.println("onRestart");
}
}
3.Activity之间传递参数
1>传递简单数据
//1.在Main和NewActivity的layout各自建立一个btn和textView,并且设置其id
//2.在MainActivity中
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
findViewById(R.id.pusnButton).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(MainActivity.this,ReceiveAct.class);
i.putExtra("data","post nsnotificaition");//传值
startActivity(i);
}
});
}
}
//3.在NewActivity中
public class ReceiveAct extends AppCompatActivity {
private TextView tv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_receive);
Intent i = getIntent();
tv = (TextView)findViewById(R.id.myId);
tv.setText(i.getStringExtra("data"));//接收值
}
}
2>传递数据包
//1.Main上
Bundle b = new Bundle();
//i.putExtra("data",b);
i.putExtras(b);
//2，New上
// Bundle data = i.getBundleExtra("data")
Bundle data = i.getExtras();
3>传递对象
//1.传递的class要序列化
public class User implements Serializable{
private String name;
private int age;
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public User(String name,int age){
this.name = name;
this.age = age;
}
}
//2.Main
i.putExtra("user",new User("Tom",18));
startActivity(i);
//3.New
User user = (User) i.getSerializableExtra("user");//输出序列号格式，并且强转
tv.setText(String.format("name = %s age = age",user.getName(),user.getAge()));
4>.获取Activity的返回参数
//1.首先惯例Main跳转，New添加EditText，backBtn
//2.New上
public class ReceiveAct extends AppCompatActivity {
private EditText editText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_receive);
editText = (EditText)findViewById(R.id.editText);
findViewById(R.id.backButton).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = getIntent();
i.putExtra("data",editText.getText().toString());
setResult(1,i);//1.是状态吗，自定义。
finish();
}
});
}
}
//3.Main上接收数据
public class MainActivity extends AppCompatActivity {
private TextView textView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = (TextView)findViewById(R.id.textView);
findViewById(R.id.pusnButton).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent i = new Intent(MainActivity.this,ReceiveAct.class);
// startActivity(i);
startActivityForResult(i,0);//必须使用能新接收结果的start方法
}
});
}
//接收结果的代理方法
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
textView.setText(data.getStringExtra("data"));
}
}
4.Android中的Activity启动模式
1>.标准启动模式 standard
tv = (TextView)findViewById(R.id.textView);
tv.setText(String.format("TaskID:%s \n current Activity:%s",getTaskId(),toString()));
findViewById(R.id.pushBtn).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(MainActivity.this,MainActivity.class));
}
});
2>.singleTol
跳转前后，任务栈都是一样的。如果处于栈顶（例如自己跳转到自己）,就不会创建实例
3>.singleTask与singleInstance
singleTask：Main跳到New，此时，内存就有Main和New两个界面。New再跳Main，New就会直接弹出栈，不在内存中了。
singleInstance：Main跳到New，任务栈发生改变。当New跳到Main，任务栈也发生变化，所以独立任务栈只放一个实例。两者来回切换
5.创建全新的Activity
//1.创建一个layout
//2.先创建好一个class，继承Activity。再创建onCreate方法
public class AnotherAtr extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.another_atr);//
}
}
//3.在AndoridMainifest中添加新的Activity的class名字
<activity android:name=".AnotherAtr"></activity>