这周的任务是实现简单的四则运算，包括完成生成随机数，包括随机生成几组数字，生成随机数的范围，加减乘除四则运算符号。由于会的东西不怎么多，所以用的都是从网上学到的简单的代码。

界面：

代码：

public class MainActivity extends MyActivity {
private int a,b,c,ty;
private TextView tv;
private Button show,next;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv=(TextView)findViewById(R.id.textView2);
show = (Button)findViewById(R.id.button3);
next = (Button)findViewById(R.id.button4);
sz();
sw();
//点击显示按钮时显示答案
show.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
switch (ty) {
case 0:
tv.setText(a + "+" + b + "=" + (a + b));
break;
case 1:
tv.setText(a + "-" + b + "=" + (a - b));
break;
case 2:
tv.setText(a + "+" + b +"*"+ c + "="+ (a+b*c));
break;
case 3:
tv.setText(a + "+" + b +"/"+ c + "="+(a+b/c));
break;
case 4:
tv.setText(a + "-" + b +"*"+ c + "="+(a-b*c));
break;
case 5:
tv.setText(a + "-" + b +"/"+ c + "="+(a-b/c));
break;
case 6:
tv.setText(a + "*" + b + "=" + (a*b));
break;
case 7:
tv.setText(a + "/" + b + "=" + (a/b));
break;
}
}
});
//点击下一题
next.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
sz();
sw();
}
});
}
//生成随机数
private void sz(){
Random random = new Random();
random.nextInt();
a = random.nextInt(100);
b = random.nextInt(100);
c = random.nextInt(100);
ty = random.nextInt(8);
}
//显示题目
private void sw(){
switch (ty) {
case 0:
tv.setText(a + "+" + b + "=" + "?");
break;
case 1:
tv.setText(a + "-" + b + "=" + "?");
break;
case 2:
tv.setText(a + "+" + b +"*"+ c + "=" + "?");
break;
case 3:
tv.setText(a + "+" + b +"/"+ c + "=" + "?");
break;
case 4:
tv.setText(a + "-" + b +"*"+ c + "=" + "?");
break;
case 5:
tv.setText(a + "-" + b +"/"+ c + "=" + "?");
break;
case 6:
tv.setText(a + "*" + b + "=" + "?");
break;
case 7:
tv.setText(a + "/" + b + "=" + "?");
break;
}
}
}public class MainActivity extends MyActivity {
private int a,b,c,ty;
private TextView tv;
private Button show,next;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv=(TextView)findViewById(R.id.textView2);
show = (Button)findViewById(R.id.button3);
next = (Button)findViewById(R.id.button4);
sz();
sw();
//点击显示按钮时显示答案
show.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
switch (ty) {
case 0:
tv.setText(a + "+" + b + "=" + (a + b));
break;
case 1:
tv.setText(a + "-" + b + "=" + (a - b));
break;
case 2:
tv.setText(a + "+" + b +"*"+ c + "="+ (a+b*c));
break;
case 3:
tv.setText(a + "+" + b +"/"+ c + "="+(a+b/c));
break;
case 4:
tv.setText(a + "-" + b +"*"+ c + "="+(a-b*c));
break;
case 5:
tv.setText(a + "-" + b +"/"+ c + "="+(a-b/c));
break;
case 6:
tv.setText(a + "*" + b + "=" + (a*b));
break;
case 7:
tv.setText(a + "/" + b + "=" + (a/b));
break;
}
}
});
//点击下一题
next.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
sz();
sw();
}
});
}
//生成随机数
private void sz(){
Random random = new Random();
random.nextInt();
a = random.nextInt(100);
b = random.nextInt(100);
c = random.nextInt(100);
ty = random.nextInt(8);
}
//显示题目
private void sw(){
switch (ty) {
case 0:
tv.setText(a + "+" + b + "=" + "?");
break;
case 1:
tv.setText(a + "-" + b + "=" + "?");
break;
case 2:
tv.setText(a + "+" + b +"*"+ c + "=" + "?");
break;
case 3:
tv.setText(a + "+" + b +"/"+ c + "=" + "?");
break;
case 4:
tv.setText(a + "-" + b +"*"+ c + "=" + "?");
break;
case 5:
tv.setText(a + "-" + b +"/"+ c + "=" + "?");
break;
case 6:
tv.setText(a + "*" + b + "=" + "?");
break;
case 7:
tv.setText(a + "/" + b + "=" + "?");
break;
}
}
}

 虚拟机运算结果：

生成四则运算