第39天~~又是JSON+动态增加按钮不是用XML

这篇的上一篇:https://ithelp.ithome.com.tw/articles/10283923

~又是JSON~~要把JSON练熟~
https://zh.wikipedia.org/wiki/JSON

这里要用logcat取出JSON的方法:

先建立新的Android档-

用logcat取出JSON的方法:

package com.huang.json2;

import androidx.appcompat.app.AppCompatActivity;

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

public class MainActivity extends AppCompatActivity {

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

        String json = String.format("{\"%s\":\"%s\"}","firstName","Ken");
        Log.d("Howard","Json"+json);
    }
}

使用Android内建套件
把错误"印"出来~

目前变这样

然後再来改内容

package com.huang.json2;

import androidx.appcompat.app.AppCompatActivity;

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

import org.json.JSONException;
import org.json.JSONObject;

public class MainActivity extends AppCompatActivity {

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

        String json = String.format("{\"%s\":\"%s\"}","firstName","Ken");
        Log.d("Howard","Json"+json);

        try {
            JSONObject obj =new JSONObject(json);
        } catch (JSONException e) {
            Log.e("Howard","JSONException"+e);
        }
    }
}

再来取出数字:

跑一下取出KEN

package com.huang.json2;

import androidx.appcompat.app.AppCompatActivity;

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

import org.json.JSONException;
import org.json.JSONObject;

public class MainActivity extends AppCompatActivity {

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

        String json = String.format("{\"%s\":\"%s\"}","firstName","Ken");
        Log.d("Howard","Json"+json);

        try {
            JSONObject obj =new JSONObject(json);

            String firstName = obj.getString("firstName");
            Log.d("Howard","firstName:"+firstName);

        } catch (JSONException e) {
            Log.e("Howard","JSONException"+e);
        }
    }
}

动态增加按钮不是用XML

开新档案-
XML档先改成-LinearLayout

XML里面只有放...

命名- containerView

然後用JAVA档-然後用JAVA档-

package com.huang.dynamic_ui;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.Button;
import android.widget.LinearLayout;

public class MainActivity extends AppCompatActivity {

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

        LinearLayout layout=findViewById(R.id.containerView);

        Button button = new Button(this);
        button.setText("存档");
        layout.addView(button);

    }
}

就可以长出这样~

然後再加入for回圈

package com.huang.dynamic_ui;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.LinearLayout;

public class MainActivity extends AppCompatActivity {

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

        LinearLayout layout=findViewById(R.id.containerView);

        Button button = new Button(this);
        button.setText("存档");
        layout.addView(button);

        for(int i=1;i <=10;i ++){
            CheckBox checkBox = new CheckBox(this);
            checkBox.setText("Item:" + i);
            layout.addView(checkBox);

        }

        

    }
}

就长成这样: