第10天~生命周期

每本安卓课本的第1步

用程序码来走一次:

1-贴两个xml档-(代做)

2-看下面的logcat看过滤器-只看想看的

3-选最下面的

4-打内容-还没有开始打的样子

5-打内容-有打的样子

6-按OK

7-目前还没有看到东西

8-activity_main.xml里面有四个按钮-要onclick

没有把


<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"

</androidx.constraintlayout.widget.ConstraintLayout>

改成

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

</LinearLayout>

改完後

再去改成orientation="vertical"

再去改 layout_width="match_parent" 和 layout_height="wrap_content"

改上+左+右内距-

改text内容

制定onClick

绑定onClick

9-到java档

从初始化开始.看到整个页面

package com.huang.mylifecycle;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;
import android.view.View;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.i("lifecycle","Activity 初始化");
    }

    public void onClick(View view) {
    }
}

呼叫onstart方法是:

1.右键-

2.选alt+insert
选onStart():void 一定要大小写符合

生出来~

准备就绪就是启动

package com.huang.mylifecycle;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;
import android.view.View;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.i("lifecycle","Activity 初始化");
    }

    @Override
    protected void onStart() {
        super.onStart();
        Log.i("lifecycle","Activity 准备就绪");
    }

    public void onClick(View view) {
    }
}

再来也是右键选到onResume()

package com.huang.mylifecycle;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;
import android.view.View;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.i("lifecycle","Activity 初始化");
    }

    @Override
    protected void onStart() {
        super.onStart();
        Log.i("lifecycle","Activity 准备就绪");
    }

    @Override
    protected void onResume() {
        super.onResume();
        Log.i("lifecycle","Activity 元件可互动操作的状态");
    }

    public void onClick(View view) {
    }
}

再来是onPause

package com.huang.mylifecycle;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;
import android.view.View;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.i("lifecycle","Activity 初始化");
    }

    @Override
    protected void onStart() {
        super.onStart();
        Log.i("lifecycle","Activity 准备就绪");
    }

    @Override
    protected void onResume() {
        super.onResume();
        Log.i("lifecycle","Activity 元件可互动操作的状态");
    }

    @Override
    protected void onPause() {
        super.onPause();
        Log.i("lifecycle","Activity 暂停");
    }

    public void onClick(View view) {
    }
}

再来是onRestart

onStop

销毁-onDestroy

package com.huang.mylifecycle;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;
import android.view.View;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.i("lifecycle","Activity 初始化");
    }

    @Override
    protected void onStart() {
        super.onStart();
        Log.i("lifecycle","Activity 准备就绪");
    }

    @Override
    protected void onResume() {
        super.onResume();
        Log.i("lifecycle","Activity 元件可互动操作的状态");
    }

    @Override
    protected void onPause() {
        super.onPause();
        Log.i("lifecycle","Activity 暂停");
    }

    @Override
    protected void onRestart() {
        super.onRestart();
        Log.i("lifecycle","Activity 恢复使用");
    }

    @Override
    protected void onStop() {
        super.onStop();
        Log.i("lifecycle","Activity 元件停止使用,不显示");
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        Log.i("lifecycle","Activity 销毁");
    }

    public void onClick(View view) {
    }
}

执行模拟器看-

用onClick来做按钮-用switch来看哪个按钮被按到
预计要放入网址:https://jzs2home.github.io/blog/admin/blogs.html

package com.huang.mylifecycle;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.util.Log;
import android.view.View;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.i("lifecycle","Activity 初始化");
    }

    @Override
    protected void onStart() {
        super.onStart();
        Log.i("lifecycle","Activity 准备就绪");
    }

    @Override
    protected void onResume() {
        super.onResume();
        Log.i("lifecycle","Activity 元件可互动操作的状态");
    }

    @Override
    protected void onPause() {
        super.onPause();
        Log.i("lifecycle","Activity 暂停");
    }

    @Override
    protected void onRestart() {
        super.onRestart();
        Log.i("lifecycle","Activity 恢复使用");
    }

    @Override
    protected void onStop() {
        super.onStop();
        Log.i("lifecycle","Activity 元件停止使用,不显示");
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        Log.i("lifecycle","Activity 销毁");
    }

    public void onClick(View view) {
        switch (view.getId()){
            case R.id.button1://执行某功能
                String url="";

        }        
    }
}

预计要放入网址:https://jzs2home.github.io/blog/admin/blogs.html

放入Intent指定+放条件:指定开启要看的动作

设定Intent去找适合看URL的语法:

public void onClick(View view) {
        switch (view.getId()){
            case R.id.button1://执行某功能
                String url="https://jzs2home.github.io/blog/admin/blogs.html";
                Intent web = new Intent(Intent.ACTION_VIEW);
                web.setData(Uri.parse(url));
                startActivity(web);
                break;

        }

第1个按钮程序码:

package com.huang.mylifecycle;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.View;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.i("lifecycle","Activity 初始化");
    }

    @Override
    protected void onStart() {
        super.onStart();
        Log.i("lifecycle","Activity 准备就绪");
    }

    @Override
    protected void onResume() {
        super.onResume();
        Log.i("lifecycle","Activity 元件可互动操作的状态");
    }

    @Override
    protected void onPause() {
        super.onPause();
        Log.i("lifecycle","Activity 暂停");
    }

    @Override
    protected void onRestart() {
        super.onRestart();
        Log.i("lifecycle","Activity 恢复使用");
    }

    @Override
    protected void onStop() {
        super.onStop();
        Log.i("lifecycle","Activity 元件停止使用,不显示");
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        Log.i("lifecycle","Activity 销毁");
    }

    public void onClick(View view) {
        switch (view.getId()){
            case R.id.button1://执行某功能
                String url="https://jzs2home.github.io/blog/admin/blogs.html";
                Intent web = new Intent(Intent.ACTION_VIEW);
                web.setData(Uri.parse(url));
                startActivity(web);
                break;

        }
    }
}

button2-要到新增跳页的画面-

新增跳页的画面page2-

等初始化完-

 case R.id.button2://开启指定页面
                Intent page = new Intent(this,Page2.class);
                startActivity(page);
                break;

到第2按钮完整程序码:

package com.huang.mylifecycle;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.View;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.i("lifecycle","Activity 初始化");
    }

    @Override
    protected void onStart() {
        super.onStart();
        Log.i("lifecycle","Activity 准备就绪");
    }

    @Override
    protected void onResume() {
        super.onResume();
        Log.i("lifecycle","Activity 元件可互动操作的状态");
    }

    @Override
    protected void onPause() {
        super.onPause();
        Log.i("lifecycle","Activity 暂停");
    }

    @Override
    protected void onRestart() {
        super.onRestart();
        Log.i("lifecycle","Activity 恢复使用");
    }

    @Override
    protected void onStop() {
        super.onStop();
        Log.i("lifecycle","Activity 元件停止使用,不显示");
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        Log.i("lifecycle","Activity 销毁");
    }

    public void onClick(View view) {
        switch (view.getId()){
            case R.id.button1://执行某功能
                String url="https://jzs2home.github.io/blog/admin/blogs.html";
                Intent web = new Intent(Intent.ACTION_VIEW);
                web.setData(Uri.parse(url));
                startActivity(web);
                break;

            case R.id.button2://开启指定页面
                Intent page = new Intent(this,Page2.class);
                startActivity(page);
                break;


        }
    }
}

灰色的地方贴CODE看不见.用截图的~

Intent是重点:

到第3按钮: 开启对话框-至少要有一个确定的按钮~

builder.setPositiveButton();是确定的按钮意思

case R.id.button3://开启对话框
                AlertDialog.Builder builder = new AlertDialog.Builder(this);//显示出对话框
                builder.setMessage("Are you OK?");//对话框内容
                builder.setPositiveButton("OK",null);//对话框按钮.之後甚麽都不做
                builder.show();//显示出来
                break;

到第4按钮:离开页面就-销毁本页面,因为onDestroy是系统设定.这里是手动.所以用finish();

case R.id.button4://销毁本页面
                finish();
                break;

完整的code

package com.huang.mylifecycle;

import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.View;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.i("lifecycle","Activity 初始化");
    }

    @Override
    protected void onStart() {
        super.onStart();
        Log.i("lifecycle","Activity 准备就绪");
    }

    @Override
    protected void onResume() {
        super.onResume();
        Log.i("lifecycle","Activity 元件可互动操作的状态");
    }

    @Override
    protected void onPause() {
        super.onPause();
        Log.i("lifecycle","Activity 暂停");
    }

    @Override
    protected void onRestart() {
        super.onRestart();
        Log.i("lifecycle","Activity 恢复使用");
    }

    @Override
    protected void onStop() {
        super.onStop();
        Log.i("lifecycle","Activity 元件停止使用,不显示");
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        Log.i("lifecycle","Activity 销毁");
    }

    public void onClick(View view) {
        switch (view.getId()){
            case R.id.button1://执行某功能
                String url="https://jzs2home.github.io/blog/admin/blogs.html";
                Intent web = new Intent(Intent.ACTION_VIEW);
                web.setData(Uri.parse(url));
                startActivity(web);
                break;

            case R.id.button2://开启指定页面
                Intent page = new Intent(this,Page2.class);
                startActivity(page);
                break;

            case R.id.button3://开启对话框
                AlertDialog.Builder builder = new AlertDialog.Builder(this);//显示出对话框
                builder.setMessage("Are you OK?");//对话框内容
                builder.setPositiveButton("OK",null);//对话框按钮.之後甚麽都不做
                builder.show();//显示出来
                break;

            case R.id.button4://销毁本页面
                finish();
                break;
        }
    }
}