# 9/21 Android from scratch

###### tags: `android` `java`

[TOC]

## Import library
alt + enter

## Create button event

public void  button1Click(View view){

}

## Counter

### Get element ID

TextView output = (TextView) findViewById(R.id.ouput1);

R is mean the resource folder


### Get output text and turn into a integer.

count = Integer.parseInt(output.getText().toString());

### Pass the value to the element

output.setText(Integer.toString(count)); 

## Source Code

### Practice 1

package com.example.test1;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

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


    public void  button1Click(View view){
        int count;
        TextView output = (TextView) findViewById(R.id.ouput1);
        count = Integer.parseInt(output.getText().toString());
        count++;
        output.setText(Integer.toString(count));
    }
    public void  button2Click(View view){
        TextView output = (TextView) findViewById(R.id.ouput1);
        output.setText("0");
    }
}


## practice 2

package com.example.inputtextandshow;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

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

    public void buttonClick(View view){
        EditText nameInput = (EditText) findViewById(R.id.nameInput);
        String userName = nameInput.getText().toString();

        TextView outputName = (TextView) findViewById(R.id.showName);
        outputName.setText("Hello" + userName);
    }
}


> [time=Thu, Sep 22, 2022 8:11 PM] Finished
> [name=侯智晟]
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