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Java 8 - filter collections with multiple conditions
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In this article, we would like to show you how to filter collections using stream in Java 8.
In this example, we use stream filter() method with multiple conditions (&& operator) to make a list of bank accounts where:
- the account number is greater than 2,
- balance is more than 100 USD.
Practical example:
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import java.io.*;2
import java.util.ArrayList;3
import java.util.List;4
import java.util.stream.Collectors;5
6
7
public class Example {8
9
public static void main(String[] args) throws IOException {10
BankAccount account1 = new BankAccount(1, 100);11
BankAccount account2 = new BankAccount(2, 101);12
BankAccount account3 = new BankAccount(3, 102);13
14
List<BankAccount> accounts = new ArrayList<>();15
accounts.add(account1);16
accounts.add(account2);17
accounts.add(account3);18
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List<BankAccount> accountsWithMoreThan100USD = accounts20
.stream()21
.filter(x -> x.getBalance() > 100 && x.getAccountNumber() > 2)22
.collect(Collectors.toList());23
24
System.out.println(accountsWithMoreThan100USD);25
}26
}Output:
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[BankAccount{ number=3, balance=102 USD }]In this example, we use multiple filter() methods with method reference to make a list of bank accounts where:
- the account number is greater than 2,
- balance is more than 100 USD.
In this case, we need to add the following methods to the BankAccount class:
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public boolean hasMoreThan100USD() {2
return this.balance > 100;3
}4
5
public boolean isMoreThanTwo() {6
return this.accountNumber > 2;7
}Practical example:
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import java.io.*;2
import java.util.ArrayList;3
import java.util.List;4
import java.util.stream.Collectors;5
6
7
public class Example {8
9
public static void main(String[] args) throws IOException {10
BankAccount account1 = new BankAccount(1, 100);11
BankAccount account2 = new BankAccount(2, 101);12
BankAccount account3 = new BankAccount(3, 102);13
14
List<BankAccount> accounts = new ArrayList<>();15
accounts.add(account1);16
accounts.add(account2);17
accounts.add(account3);18
19
List<BankAccount> accountsWithMoreThan100USD = accounts20
.stream()21
.filter(BankAccount::isMoreThanTwo)22
.filter(BankAccount::hasMoreThan100USD)23
.collect(Collectors.toList());24
25
System.out.println(accountsWithMoreThan100USD);26
}27
}Output:
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[BankAccount{ number=3, balance=102 USD }]BankAccount.java:
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public class BankAccount {2
private final int accountNumber;3
// for simplicity reason we keep USD in int4
private final int balance;5
6
public BankAccount(int accountNumber, int balance) {7
this.accountNumber = accountNumber;8
this.balance = balance;9
}10
11
public int getAccountNumber() {12
return accountNumber;13
}14
15
public double getBalance() {16
return balance;17
}18
19
public boolean hasMoreThan100USD() {20
return this.balance > 100;21
}22
23
public boolean isMoreThanTwo() {24
return this.accountNumber > 2;25
}26
27
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public String toString() {29
return "BankAccount{ " +30
"number=" + accountNumber +31
", balance=" + balance +32
" USD }";33
}34
}