012/MyFirstApp

/MyFirstApp/src/com/qq/wen/myfirstapp/MainActivity.java
package com.qq.wen.myfirstapp;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends Activity {

private Button button;
private TextView textView;

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

button = findViewById(R.id.button);
textView = findViewById(R.id.textView);

button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = textView.getText().toString();
textView.setText(text + "2");
}
});
}
}

/MyFirstApp/src/com/qq/wen/myfirstapp/MainActivity.java
package com.qq.wen.myfirstapp;

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

public class MainActivity extends Activity {

private Button button;
private TextView textView;

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

button = findViewById(R.id.button);
textView = findViewById(R.id.textView);

button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = textView.getText().toString();
textView.setText(text + "2");
}
});

Button button1 = findViewById(R.id.button1);
button1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = textView.getText().toString();
textView.setText(text + "1");
}
});
}
}

/MyFirstApp/src/com/qq/wen/myfirstapp/MainActivity.java
package com.qq.wen.myfirstapp;

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

public class MainActivity extends Activity {

private Button button;
private TextView textView;

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

button = findViewById(R.id.button);
textView = findViewById(R.id.textView);

button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = textView.getText().toString();
textView.setText(text + "2");
}
});

Button button1 = findViewById(R.id.button1);
button1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = textView.getText().toString();
textView.setText(text + "1");
}
});

Button button2 = findViewById(R.id.button2);
button2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = textView.getText().toString();
textView.setText(text + "3");
}
});
}
}

/MyFirstApp/src/com/qq/wen/myfirstapp/MainActivity.java
package com.qq.wen.myfirstapp;

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

public class MainActivity extends Activity {

private Button button;
private TextView textView;

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

button = findViewById(R.id.button);
textView = findViewById(R.id.textView);

button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = textView.getText().toString();
textView.setText(text + "2");
}
});

Button button1 = findViewById(R.id.button1);
button1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = textView.getText().toString();
textView.setText(text + "1");
}
});

Button button2 = findViewById(R.id.button2);
button2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = textView.getText().toString();
textView.setText(text + "3");
}
});

Button button3 = findViewById(R.id.button3);
button3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = textView.getText().toString();
textView.setText(text + "4");
}
});
}
}

/MyFirstApp/src/com/qq/wen/myfirstapp/MainActivity.java
package com.qq.wen.myfirstapp;

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

public class MainActivity extends Activity {

private Button button;
private TextView textView;

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

button = findViewById(R.id.button);
textView = findViewById(R.id.textView);

button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = textView.getText().toString();
textView.setText(text + "2");
}
});

Button button1 = findViewById(R.id.button1);
button1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = textView.getText().toString();
textView.setText(text + "1");
}
});

Button button2 = findViewById(R.id.button2);
button2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = textView.getText().toString();
textView.setText(text + "3");
}
});

Button button3 = findViewById(R.id.button3);
button3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = textView.getText().toString();