Article Directory
1. Introduction of Intent
(1) What is Intent
Intent is a runtime binding mechanism used to connect two different components during the running of the program. In short, Intent is a mechanism that assists in the interaction and communication between applications.
(B) Intent related attributes
| Attributes | description |
|---|---|
| component | Destination component |
| action | Act of expressing intent |
| category | Type of performance |
| data | Data to be manipulated with the action |
| type (data type) | description of data |
| extras (extended information) | Extended Information |
Second, the actual use of Intent
(1) Display intention
Clearly indicate the component name.
1. Method One
//this指向当前的Activity，后面填写内容为需要跳转的Activity
intent.setClass(this,ClockActivity.class);
2. Method two
///this指向当前的Activity，后面是要跳转Activity的全类名
intent.setClassName(this,"com.example.intentthreetype.DateActivity");
3. Method Three
//前面内容是要打开Activity的项目名，后面是要跳转项目中Activity的全类名
intent.setClassName("com.example.helloworld","com.example.helloworld.MainActivity");
(2) Implicit intention
Do not directly specify the component name.
The intent-filter (intent filter)
adds an intent filter to the activity by setting the AndroidManifest.xml file, and sets the action.
<activity android:name=".Show_Image">
<intent-filter>
<action android:name="openimage" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
Three, examples
(1) Examples of display intentions
There are three ways to achieve access to another Activity
MainActivity code (only the more important part of the code is given)
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private Button type1_btn;
private Button type2_btn;
private Button type3_btn;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
type1_btn=findViewById(R.id.type1_btn);
type2_btn=findViewById(R.id.type2_btn);
type3_btn=findViewById(R.id.type3_btn);
type1_btn.setOnClickListener(this);
type2_btn.setOnClickListener(this);
type3_btn.setOnClickListener(this);
}
@Override
public void onClick(View view) {
Intent intent=new Intent();
switch (view.getId())
{
case R.id.type1_btn:
intent.setClass(this,ClockActivity.class);
break;
case R.id.type2_btn:
intent.setClassName(this,"com.example.intentthreetype.DateActivity");
break;
case R.id.type3_btn:
intent.setClassName("com.example.helloworld","com.example.helloworld.MainActivity");
break;
}
startActivity(intent);
}
}
Final display effect
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(2) Examples of implicit intentions
Enter another Activity
MainActivity code through the button
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
Button btn_image;
@SuppressLint("WrongViewCast")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btn_image=findViewById(R.id.imageshow);
btn_image.setOnClickListener(this);
}
@Override
public void onClick(View view) {
Intent intent=new Intent();
intent.setAction("openimage");
intent.addCategory(Intent.CATEGORY_DEFAULT);
startActivity(intent);
}
}
AndroidManifest.xml code
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.imageshow">
<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/Theme.ImageShow">
<activity android:name=".Show_Image">
<intent-filter>
<action android:name="openimage" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
display effect
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